From 7059e59cddc1c81321639875636e88895bc14309 Mon Sep 17 00:00:00 2001 From: José Bollo Date: Thu, 23 Jun 2016 20:34:57 +0200 Subject: vocabulary: moving from 'plugin' to 'binding' MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Change-Id: Ic9e118df2bede1fefbb591f8ae7887266b7324ca Signed-off-by: José Bollo --- doc/FAQ.html | 2 +- doc/afb-application-writing.html | 2 +- doc/afb-bindings-overview.html | 157 +++++ doc/afb-bindings-overview.md | 168 ++++++ doc/afb-bindings-writing.html | 951 +++++++++++++++++++++++++++++ doc/afb-bindings-writing.md | 1227 ++++++++++++++++++++++++++++++++++++++ doc/afb-daemon-vocabulary.html | 14 +- doc/afb-daemon-vocabulary.md | 16 +- doc/afb-overview.html | 42 +- doc/afb-overview.md | 44 +- doc/afb-plugin-writing.html | 953 ----------------------------- doc/afb-plugin-writing.md | 1227 -------------------------------------- doc/afb-plugins-overview.html | 159 ----- doc/afb-plugins-overview.md | 168 ------ doc/afb-tests-overview.html | 6 +- doc/afb-tests-overview.md | 4 +- 16 files changed, 2573 insertions(+), 2567 deletions(-) create mode 100644 doc/afb-bindings-overview.html create mode 100644 doc/afb-bindings-overview.md create mode 100644 doc/afb-bindings-writing.html create mode 100644 doc/afb-bindings-writing.md delete mode 100644 doc/afb-plugin-writing.html delete mode 100644 doc/afb-plugin-writing.md delete mode 100644 doc/afb-plugins-overview.html delete mode 100644 doc/afb-plugins-overview.md (limited to 'doc') diff --git a/doc/FAQ.html b/doc/FAQ.html index 0cad0b5b..e5f64273 100644 --- a/doc/FAQ.html +++ b/doc/FAQ.html @@ -16,7 +16,7 @@

Frequently Asked Question about AFB-DAEMON

José Bollo

27 mai 2016

10 juin 2016

HOWTO WRITE an APPLICATION above AGL FRAMEWORK

José Bollo

Fulup Ar Foll

09 juin 2016

10 juin 2016

Overview of bindings shipped with AFB-Daemon

José Bollo

23 juin 2016

Overview of bindings shipped with AFB-Daemon

Version: 1
+Date:    09 juin 2016
+Author:  Manuel Bachmann

List of bindings

Here are the bindings shipped in the source tree:

Hello World
Authentication
Tic Tac Toe
Audio (2 backends: ALSA/PulseAudio)
Radio (1 backend: RTLSDR RTL2832U)
Media (1 backend: Rygel UPnP)

All bindings may not be built, depending on the development libraries present on the system at build time.

Detail of bindings

Hello World

A sample Hello World binding for demonstration and learning purposes.

This binding provides a few unauthenticated requests, all beginning with "ping", to demonstrate basic binder capabilities.

Verbs:

ping: returns a success response
pingfail: returns a failure response
pingnull: returns a success response, with an empty JSON response field
pingbug: does a memory violation (intercepted by the binder)
pingJson: returns a success response, with a complex JSON response field
pingevent: broadcasts a global event

Authentication

An sample Authentication binding for demonstration purposes.

This binding provides a few requests to demonstrate the binder's token-based security mechanism.

Calling "connect" with a security token will initiate a session, calling "refresh" will issue a new token and invalidate the previous one, calling "logout" will invalidate all tokens and close the session.

Verbs:

ping: returns a success response
connect: creates a session and returns a new token
refresh: returns a new token
check: verifies the passed token is valid
logout: closes the session

Tic Tac Toe

A sample Tic Tac Toe game binding.

This binding provides an interactive Tic Tac Toe game where the binder returns the grid as a JSON response.

Verbs:

new: starts a new game
play: asks the server to play
move: gives a client move
board: gets the current board state, as a JSON structure
level: sets the server level
join: joins an existing board
undo: undo the last move
wait: wait for a move

Audio

A sample Audio binding with 2 backends:

ALSA (mandatory)
PulseAudio (optional)

This binding is able to initialize a specific soundcard, define volume levels, channels (mono/stereo...), mute sound, and play a 22,050 Hz PCM stream.

Verbs:

ping: returns a success response
init: initializes backend, on the "default" sound card
volume: gets or sets volume, in % (0-100)
channels: gets or sets channels count (1-8)
mute: gets or sets the mute status (on-off)
play: gets or sets the playing status (on-off)

(if PulseAudio development libraries are not found at build time, only ALSA will be available)

(if a PulseAudio server is not found at runtime, the binding will dynamically fall back to ALSA)

(a specifc backend can be forced by using this syntax before running afb-daemon : $ export AFB_AUDIO_OUTPUT=Alsa)

Radio

A sample AM/FM Radio binding with 1 backend:

RTLSDR - Realtek RTL2832U dongles (mandatory)

This binding is able to initialize specific RTL2832U dongles, switch between AM/FM modes, define frequency, mute sound, and play sound (if combining with the audio binding).

Verbs:

ping: returns a success response
init: initializes backend, looking for plugged-in devices
power: sets device power status (on-off)
mode: sets device reception mode (AM-FM)
freq: sets device frequency (in Hz)
mute: sets device mute status (on-off)
play: sets device playing status (on-off)

(if rtlsdr development libraries are not found at build time, this binding will not be built)

Media

A sample Media Server binding with 1 backend:

Rygel

This binding is able to detect a local Rygel UPnP media server, list audio files, select an audio file for playback, play/pause/seek in this file, upload an audio file to the server.

Verbs:

ping: returns a success response
init: initializes backend, looking for an active local UPnP server
list: returns list of audio files, as a JSON structure
select: select an audio files, by index number (001-...)
play: plays the currently selected audio file
stop: stops the currently selected audio file
pause: pauses the currently selected audio file
seek: seeks in the currently selected audio file, in seconds
upload: uploads an audio file, with a POST request

(if GUPnP/GSSDP development libraries are not fund at build time, this binding will not be built)

Sample command-line applications: afb-client-demo (built by default)

Sample HTML5 applications: **test/*.html, afb-client, afb-radio**

Sample Qt/QML applications: test/token-websock.qml

HOWTO WRITE a BINDING for AFB-DAEMON

José Bollo

23 juin 2016

HOWTO WRITE a BINDING for AFB-DAEMON

version: 1
+Date:    09 juin 2016
+Author:  José Bollo

Summary

Afb-daemon binders serve files through HTTP protocol and offers to developers the capability to expose application API methods through HTTP or WebSocket protocol.

Binder bindings are used to add API to afb-daemon. This part describes how to write a binding for afb-daemon.

Excepting this summary, this document target developers.

Before moving further through an example, here after a short overview of binder bindings fundamentals.

Nature of a binding

A binding is an independent piece of software. A binding is self contain and exposes application logic as sharable library. A binding is intended to be dynamically loaded by afb-daemon to expose application API.

Technically, a binder binding does not reference and is not linked with any afb-daemon library.

Class of bindings

Application binder supports two kinds of bindings: application bindings and service bindings. Technically both class of binding are equivalent are use the same coding convention. Only sharing mode and security context diverge.

Application-bindings

Application-bindings implements the glue in between application's UI and services. Every AGL application has a corresponding binder that typically activates one or many bindings to interface the application logic with lower platform services. When an application is started by the AGL application framework, a dedicate binder is started that loads/activates application binding(s). API expose by application-binding are executed within corresponding application security context.

Application bindings generally handle a unique context for a unique client. As the application framework start a dedicated instance of afb_daemon for each AGL application, if a given binding is used within multiple application each of those application get a new and private instance of eventually "shared" binding.

Service-bindings

Service-bindings enable API activation within corresponding service security context and not within calling application context. Service-bindings are intended to run as a unique instance. Service-bindings can be shared in between multiple clients.

Service-bindings can either be stateless or manage client context. When managing context each client get a private context.

Sharing may either be global to the platform (ie: GPS service) or dedicated to a given user (ie: user preferences)

Live cycle of bindings within afb-daemon

Application and service bindings are loaded and activated each time a new afb-daemon is started.

At launch time, every loaded binding initialise itself. If a single binding initialisation fail corresponding instance of afb-daemon self aborts.

Conversely, when a binding initialisation succeeds, it should register its unique name as well as the list of verbs attached to the methods it exposes.

When initialised, on request from application clients to the right API/verb, binding methods are activated by the afb-daemon attached to the application or service.

At exit time, no special action is enforced by afb-daemon. When a specific actions is required at afb-daemon stop, developers should use 'atexit/on_exit' during binding initialisation sequence to register a custom exit function.

Binding Contend

Afb-daemon's binding register two classes of objects: names and functions.

Bindings declare categories of names: - A unique binding name to access all API expose by this binding, - One name for each methods/verbs provided by this binding.

Bindings declare two categories of functions: - function use for the initialisation - functions implementing exposed API methods

Afb-daemon parses URI requests to extract the API(binding name) and the VERB(method to activate). As an example, URI foo/bar translates to binding named foo and method named bar. To serve such a request, afb-daemon looks for an active binding named foo and then within this binding for a method named bar. When find afb-daemon calls corresponding method with attached parameter if any.

Afb-daemon ignores letter case when parsing URI. Thus TicTacToe/Board and tictactoe/board are equivalent.

The name of the binding

The name of a given binding is also known as the name of the API prefix that defines the binding.

The name of a binding SHOULD be unique within a given afb-daemon instance.

For example, when a client of afb-daemon calls a URI named foo/bar. Afb-daemon extracts the prefix foo and the suffix bar. foo must match a binding name and bar a VERB attached to some method.

Names of methods

Each binding exposes a set of methods that can be called by the clients of a given afb-daemon.

VERB's name attached to a given binding (API) MUST be unique within a binding.

Bindings static declaration link VERBS to corresponding methods. When clients emit requests on a given API/VERB corresponding method is called by afb-daemon.

Initialisation function

Binding's initialisation function serves several purposes.

It allows afb-daemon to control binding version depending on initialisation function name. As today, the only supported initialisation function is afbBindingV1Register. This identifies version "one" of bindings.
It allows bindings to initialise itself.
It enables names declarations: descriptions, requirements and implementations of exposed API/VERB.

Functions instantiation of API/VERBs

When an API/VERB is called, afb-daemon constructs a request object. Then it passes this request object to the implementation function corresponding to requested method, this within attached API binding.

An implementation function receives a request object that is used to: get arguments of the request, send answer, store session data.

A binding MUST set an answer to every received requests.

Nevertheless it is not mandatory to set the answer before returning from API/VERB implementing function. This behaviour is important for asynchronous actions.

API/VERB implementation that set an answer before returning are called synchronous implementations. Those that do not systematically set an answer before returning are called asynchronous implementations.

Asynchronous implementations typically launch asynchronous actions. They record some context at request time and provide answer to the request only at completion of asynchronous actions.

The Tic-Tac-Toe example

This part explains how to write an afb-binding. For the sake of being practical it uses many examples based on tic-tac-toe. This binding example is in bindings/samples/tic-tac-toe.c.

This binding is named tictactoe.

Dependencies when compiling

Afb-daemon provides a configuration file for pkg-config. Typing the command

pkg-config --cflags afb-daemon

Print flags use for compilation:

$ pkg-config --cflags afb-daemon
+-I/opt/local/include -I/usr/include/json-c

For linking, you should use

$ pkg-config --libs afb-daemon
+-ljson-c

Afb-daemon automatically includes dependency to json-c. This is activated through Requires keyword in pkg-config. While almost every binding replies on json-c this is not a must have dependency.

Internally, afb-daemon relies on libsystemd for its event loop, as well as for its binding to D-Bus. Bindings developers are encouraged to leverage libsystemd when possible. Nevertheless there is no hard dependency to libsystemd if ever you rather not use it, feel free to do so.

+
Afb-daemon binding are fully self contain. They do not enforce dependency on any libraries from the application framework. Afb-daemon dependencies requirer to run AGL bindings are given at runtime through pointers leveraging read-only memory feature.
+

Header files to include

Binding tictactoe has following includes:

#define _GNU_SOURCE
+#include <stdio.h>
+#include <string.h>
+#include <json-c/json.h>
+#include <afb/afb-binding.h>

Header afb/afb-binding.h is the only hard dependency, it includes all features that a binding MUST HAVE. Outside of includes used to support application logic, common external headers used within bindings are:

json-c/json.h: should be include to handle json objects;
systemd/sd-event.h: should be include to access event main loop;
systemd/sd-bus.h: should be include for dbus connections.

The tictactoe binding does not leverage systemd features, also only json.h is used on top of mandatory afb/afb-binding.h.

When including afb/afb-binding.h, the macro **_GNU_SOURCE** MUST be defined.

Choosing names

Designers of bindings should define a unique name for every API binding as well as for methods VERBs. They should also define names for request arguments passed as name/value pair in URI.

While forging names, designers should respect few rules to ensure that created names are valid and easy to use across platforms.

All names and strings are UTF-8 encoded.

Names for API (binding)

Binding API name are checked. All characters are authorised except:

the control characters (000 .. 01f)
the characters of the set { ' ', '"', '#', '%', '&', ''', '/', '?', '`', '7f' }

In other words the set of forbidden characters is { 000..020, 022, 023, 025..027, 02f, 03f, 060, 07f }.

Afb-daemon makes no distinction between lower case and upper case when searching for API/VERB.

Names for methods

The names of methods VERBs are totally free and not checked.

However, the validity rules for method's VERB name are the same as for Binding API name except that the dot(.) character is forbidden.

Afb-daemon makes no case distinction when searching for an API by name.

Names for arguments

Argument's name are not restricted and can be everything you wish.

+
Warning arguments search is case sensitive and "index" and "Index" are not two different arguments.
+

Forging names widely available

The key names of javascript object can be almost anything using the arrayed notation:

object[key] = value

Nevertheless this is not the case with javascript dot notation:

object.key = value

Using the dot notation, the key must be a valid javascript identifier and dash(-) as well as few other reserved characters cannot be used.

For this reason, we advise developper to chose name compatible with both javascript and HTML notation.

It is a good practice, even for arguments not to rely on case sensitivity. This may reduce headache strength at debug time, especially with interpreted language like javascript that may not warn you that a variable was not defined.

Writing a synchronous method implementation

The method tictactoe/board is a synchronous implementation. Here is its listing:

/*
+ * get the board
+ */
+static void board(struct afb_req req)
+{
+    struct board *board;
+    struct json_object *description;
+
+    /* retrieves the context for the session */
+    board = board_of_req(req);
+    INFO(afbitf, "method 'board' called for boardid %d", board->id);
+
+    /* describe the board */
+    description = describe(board);
+
+    /* send the board's description */
+    afb_req_success(req, description, NULL);
+}

This example shows many aspects of a synchronous method implementation. Let summarise it:

The function board_of_req retrieves the context stored for the binding: the board.
The macro INFO sends a message of kind INFO to the logging system. The global variable named afbitf used represents the interface to afb-daemon.
The function describe creates a json_object representing the board.
The function afb_req_success sends the reply, attaching to it the object description.

The incoming request

For any implementation, the request is received by a structure of type struct afb_req.

+
Note that this is a PLAIN structure, not a pointer to a structure.
+

The definition of struct afb_req is:

/*
+ * Describes the request by bindings from afb-daemon
+ */
+struct afb_req {
+    const struct afb_req_itf *itf;  /* the interfacing functions */
+    void *closure;          /* the closure for functions */
+};

It contains two pointers: first one itf, points to functions used to handle internal request. Second one closure point onto function closure.

+
The structure must never be used directly. Instead developer should use the intended functions provided by afb-daemon as described here after.
+

req is used to get arguments of the request, to send answer, to store session data.

This object and its interface is defined and documented in the file names afb/afb-req-itf.h

The above example uses twice req object request.

The first time, to retrieve the board attached to the session of the request.

The second time, to send the reply: an object that describes the current board.

Associating a client context to a session

When tic-tac-toe binding receives a request, it musts get the board describing the game associated to the session.

For a binding, having data associated to a session is common. This data is called "binding context" for the session. Within tic-tac-toe binding the context is the board.

Requests afb_req offer four functions for storing and retrieving session associated context.

These functions are:

afb_req_context_get: retrieves context data stored for current binding.
afb_req_context_set: store context data of current binding.
afb_req_context: if exist retrieves context data of current binding. if context does not yet exist, creates a new context and store it.
afb_req_context_clear: reset the stored context data.

The binding tictactoe use a convenient function to retrieve its context: the board. This function is board_of_req:

/*
+ * retrieves the board of the request
+ */
+static inline struct board *board_of_req(struct afb_req req)
+{
+    return afb_req_context(req, (void*)get_new_board, (void*)release_board);
+}

The function afb_req_context ensures an existing context for the session of the request. Its two last arguments are functions to allocate and free context. Note function type casts to avoid compilation warnings.

Here is the definition of the function afb_req_context

/*
+ * Gets the pointer stored by the binding for the session of 'req'.
+ * If the stored pointer is NULL, indicating that no pointer was
+ * already stored, afb_req_context creates a new context by calling
+ * the function 'create_context' and stores it with the freeing function
+ * 'free_context'.
+ */
+static inline void *afb_req_context(struct afb_req req, void *(*create_context)(), void (*free_context)(void*))
+{
+    void *result = afb_req_context_get(req);
+    if (result == NULL) {
+        result = create_context();
+        afb_req_context_set(req, result, free_context);
+    }
+    return result;
+}

The second argument if the function that creates the context. For binding tic-tac-toe (function get_new_board). The function get_new_board creates a new board and set usage its count to 1. The boards are checking usage count to free resources when not used.

The third argument is a function that frees context resources. For binding tic-tac-toe (function release_board). The function release_board decrease usage count of the board passed in argument. When usage count falls to zero, data board are freed.

Definition of other functions dealing with contexts:

/*
+ * Gets the pointer stored by the binding for the session of 'req'.
+ * When the binding has not yet recorded a pointer, NULL is returned.
+ */
+void *afb_req_context_get(struct afb_req req);
+
+/*
+ * Stores for the binding the pointer 'context' to the session of 'req'.
+ * The function 'free_context' will be called when the session is closed
+ * or if binding stores an other pointer.
+ */
+void afb_req_context_set(struct afb_req req, void *context, void (*free_context)(void*));
+
+/*
+ * Frees the pointer stored by the binding for the session of 'req'
+ * and sets it to NULL.
+ *
+ * Shortcut for: afb_req_context_set(req, NULL, NULL)
+ */
+static inline void afb_req_context_clear(struct afb_req req)
+{
+    afb_req_context_set(req, NULL, NULL);
+}

Sending reply to a request

Two kinds of replies: successful or failure.

+
Sending a reply to a request MUST be done once and only once.
+

It exists two functions for "success" replies: afb_req_success and afb_req_success_f.

/*
+ * Sends a reply of kind success to the request 'req'.
+ * The status of the reply is automatically set to "success".
+ * Its send the object 'obj' (can be NULL) with an
+ * informationnal comment 'info (can also be NULL).
+ *
+ * For conveniency, the function calls 'json_object_put' for 'obj'.
+ * Thus, in the case where 'obj' should remain available after
+ * the function returns, the function 'json_object_get' shall be used.
+ */
+void afb_req_success(struct afb_req req, struct json_object *obj, const char *info);
+
+/*
+ * Same as 'afb_req_success' but the 'info' is a formatting
+ * string followed by arguments.
+ *
+ * For conveniency, the function calls 'json_object_put' for 'obj'.
+ * Thus, in the case where 'obj' should remain available after
+ * the function returns, the function 'json_object_get' shall be used.
+ */
+void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...);

It exists two functions for "failure" replies: afb_req_fail and afb_req_fail_f.

/*
+ * Sends a reply of kind failure to the request 'req'.
+ * The status of the reply is set to 'status' and an
+ * informational comment 'info' (can also be NULL) can be added.
+ *
+ * Note that calling afb_req_fail("success", info) is equivalent
+ * to call afb_req_success(NULL, info). Thus even if possible it
+ * is strongly recommended to NEVER use "success" for status.
+ *
+ * For conveniency, the function calls 'json_object_put' for 'obj'.
+ * Thus, in the case where 'obj' should remain available after
+ * the function returns, the function 'json_object_get' shall be used.
+ */
+void afb_req_fail(struct afb_req req, const char *status, const char *info);
+
+/*
+ * Same as 'afb_req_fail' but the 'info' is a formatting
+ * string followed by arguments.
+ *
+ * For conveniency, the function calls 'json_object_put' for 'obj'.
+ * Thus, in the case where 'obj' should remain available after
+ * the function returns, the function 'json_object_get' shall be used.
+ */
+void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...);

+
For conveniency, these functions automatically call json_object_put to release obj. Because obj usage count is null after being passed to a reply function, it SHOULD not be used anymore. If exceptionally obj needs to remain usable after reply function then using json_object_get on obj to increase usage count and cancels the effect the json_object_put is possible.
+

Getting argument of invocation

Many methods expect arguments. Afb-daemon's bindings retrieve arguments by name and not by position.

Arguments are passed by requests through either HTTP or WebSockets.

For example, the method join of binding tic-tac-toe expects one argument: the boardid to join. Here is an extract:

/*
+ * Join a board
+ */
+static void join(struct afb_req req)
+{
+    struct board *board, *new_board;
+    const char *id;
+
+    /* retrieves the context for the session */
+    board = board_of_req(req);
+    INFO(afbitf, "method 'join' called for boardid %d", board->id);
+
+    /* retrieves the argument */
+    id = afb_req_value(req, "boardid");
+    if (id == NULL)
+        goto bad_request;
+    ...

The function afb_req_value searches in the request req for argument name passed in the second argument. When argument name is not passed, afb_req_value returns NULL.

+
The search is case sensitive and boardid is not equivalent to BoardId. Nevertheless having argument names that only differ by name case is not a good idea.
+

Basic functions for querying arguments

The function afb_req_value is defined here after:

/*
+ * Gets from the request 'req' the string value of the argument of 'name'.
+ * Returns NULL if when there is no argument of 'name'.
+ * Returns the value of the argument of 'name' otherwise.
+ *
+ * Shortcut for: afb_req_get(req, name).value
+ */
+static inline const char *afb_req_value(struct afb_req req, const char *name)
+{
+    return afb_req_get(req, name).value;
+}

It is defined as a shortcut to call the function afb_req_get. That function is defined here after:

/*
+ * Gets from the request 'req' the argument of 'name'.
+ * Returns a PLAIN structure of type 'struct afb_arg'.
+ * When the argument of 'name' is not found, all fields of result are set to NULL.
+ * When the argument of 'name' is found, the fields are filled,
+ * in particular, the field 'result.name' is set to 'name'.
+ *
+ * There is a special name value: the empty string.
+ * The argument of name "" is defined only if the request was made using
+ * an HTTP POST of Content-Type "application/json". In that case, the
+ * argument of name "" receives the value of the body of the HTTP request.
+ */
+struct afb_arg afb_req_get(struct afb_req req, const char *name);

That function takes 2 parameters: the request and the name of the argument to retrieve. It returns a PLAIN structure of type struct afb_arg.

There is a special name that is defined when the request is of type HTTP/POST with a Content-Type being application/json. This name is "" (the empty string). In that case, the value of this argument of empty name is the string received as a body of the post and is supposed to be a JSON string.

The definition of struct afb_arg is:

/*
+ * Describes an argument (or parameter) of a request
+ */
+struct afb_arg {
+    const char *name;   /* name of the argument or NULL if invalid */
+    const char *value;  /* string representation of the value of the argument */
+                /* original filename of the argument if path != NULL */
+    const char *path;   /* if not NULL, path of the received file for the argument */
+                /* when the request is finalized this file is removed */
+};

The structure returns the data arguments that are known for the request. This data include a field named path. This path can be accessed using the function afb_req_path defined here after:

/*
+ * Gets from the request 'req' the path for file attached to the argument of 'name'.
+ * Returns NULL if when there is no argument of 'name' or when there is no file.
+ * Returns the path of the argument of 'name' otherwise.
+ *
+ * Shortcut for: afb_req_get(req, name).path
+ */
+static inline const char *afb_req_path(struct afb_req req, const char *name)
+{
+    return afb_req_get(req, name).path;
+}

The path is only defined for HTTP/POST requests that send file.

Arguments for received files

As it is explained above, clients can send files using HTTP/POST requests.

Received files are attached to "file" argument name. For example, the following HTTP fragment (from test/sample-post.html) will send an HTTP/POST request to the method post/upload-image with 2 arguments named file and hidden.

<h2>Sample Post File</h2>
+<form enctype="multipart/form-data">
+    <input type="file" name="file" />
+    <input type="hidden" name="hidden" value="bollobollo" />
+    <br>
+    <button formmethod="POST" formaction="api/post/upload-image">Post File</button>
+</form>

Argument named file should have both its value and path defined.

The value is the name of the file as it was set by the HTTP client. Generally it is the filename on client side.

The path is the effective path of saved file on the temporary local storage area of the application. This is a randomly generated and unique filename. It is not linked with the original filename as used on client side.

After success the binding can use the uploaded file directly from local storage path with no restriction: read, write, remove, copy, rename... Nevertheless when request reply is set and query terminated, the uploaded temporary file at path is destroyed.

Arguments as a JSON object

Bindings may also request every arguments of a given call as one single object. This feature is provided by the function afb_req_json defined here after:

/*
+ * Gets from the request 'req' the json object hashing the arguments.
+ * The returned object must not be released using 'json_object_put'.
+ */
+struct json_object *afb_req_json(struct afb_req req);

It returns a json object. This object depends on how the request was built:

For HTTP requests, this json object uses key names mapped on argument name. Values are either string for common arguments or object ie: { "file": "...", "path": "..." }
For WebSockets requests, returned directly the object as provided by the client.

+
In fact, for Websockets requests, the function afb_req_value can be seen as a shortcut to json_object_get_string(json_object_object_get(afb_req_json(req), name))
+

Initialisation of the binding and declaration of methods

To be active, binding's methods should be declared to afb-daemon. Furthermore, the binding itself must be recorded.

The registration mechanism is very basic: when afb-need starts, it loads all bindings listed in: command line or configuration file.

Loading a binding follows the following steps:

Afb-daemon loads the binding with dlopen.
Afb-daemon searches for a symbol named afbBindingV1Register using dlsym. This symbol is assumed to be the exported initialisation function of the binding.
Afb-daemon builds an interface object for the binding.
Afb-daemon calls the found function afbBindingV1Register with interface pointer as parameter.
Function afbBindingV1Register setups the binding and initialises it.
Function afbBindingV1Register returns the pointer to a structure describing the binding: version, name (prefix or API name), and list of methods.
Afb-daemon checks that the returned version and name can be managed. If so, binding and its methods are register to become usable as soon as afb-daemon initialisation is finished.

Here after the code used for afbBindingV1Register from binding tic-tac-toe:

/*
+ * activation function for registering the binding called by afb-daemon
+ */
+const struct afb_binding *afbBindingV1Register(const struct afb_binding_interface *itf)
+{
+   afbitf = itf;         // records the interface for accessing afb-daemon
+   return &binding_description;  // returns the description of the binding
+}

It is a very minimal initialisation function because tic-tac-toe binding doesn't have any application related initialisation step. It merely record daemon's interface and returns its description.

The variable afbitf is a binding global variable. It keeps the interface to afb-daemon that should be used for logging and pushing events. Here is its declaration:

/*
+ * the interface to afb-daemon
+ */
+const struct afb_binding_interface *afbitf;

The description of the binding is defined here after.

/*
+ * array of the methods exported to afb-daemon
+ */
+static const struct afb_verb_desc_v1 binding_methods[] = {
+   /* VERB'S NAME     SESSION MANAGEMENT          FUNCTION TO CALL  SHORT DESCRIPTION */
+   { .name= "new",   .session= AFB_SESSION_NONE, .callback= new,   .info= "Starts a new game" },
+   { .name= "play",  .session= AFB_SESSION_NONE, .callback= play,  .info= "Asks the server to play" },
+   { .name= "move",  .session= AFB_SESSION_NONE, .callback= move,  .info= "Tells the client move" },
+   { .name= "board", .session= AFB_SESSION_NONE, .callback= board, .info= "Get the current board" },
+   { .name= "level", .session= AFB_SESSION_NONE, .callback= level, .info= "Set the server level" },
+   { .name= "join",  .session= AFB_SESSION_CHECK,.callback= join,  .info= "Join a board" },
+   { .name= "undo",  .session= AFB_SESSION_NONE, .callback= undo,  .info= "Undo the last move" },
+   { .name= "wait",  .session= AFB_SESSION_NONE, .callback= wait,  .info= "Wait for a change" },
+   { .name= NULL } /* marker for end of the array */
+};
+
+/*
+ * description of the binding for afb-daemon
+ */
+static const struct afb_binding binding_description =
+{
+   /* description conforms to VERSION 1 */
+   .type= AFB_BINDING_VERSION_1,
+   .v1= {               /* fills the v1 field of the union when AFB_BINDING_VERSION_1 */
+      .prefix= "tictactoe",     /* the API name (or binding name or prefix) */
+      .info= "Sample tac-tac-toe game", /* short description of of the binding */
+      .methods = binding_methods        /* the array describing the methods of the API */
+   }
+};

The structure binding_description describes the binding. It declares the type and version of the binding, its name, a short description and its methods list.

The list of methods is an array of structures describing the methods and terminated by a NULL marker.

In version one of afb-damon binding, a method description contains 4 fields:

the name of the method,
the session management flags,
the implementation function to be call for the method,
a short description.

The structure describing methods is defined as follows:

/*
+ * Description of one method of the API provided by the binding
+ * This enumeration is valid for bindings of type 1
+ */
+struct afb_verb_desc_v1
+{
+       const char *name;                       /* name of the method */
+       enum AFB_session_v1 session;            /* authorisation and session requirements of the method */
+       void (*callback)(struct afb_req req);   /* callback function implementing the method */
+       const char *info;                       /* textual description of the method */
+};

For technical reasons, the enumeration enum AFB_session_v1 is not exactly an enumeration but the wrapper of constant definitions that can be mixed using bitwise or (the C operator |).

The constants that can bit mixed are:

Constant name	Meaning
AFB_SESSION_CREATE	Equals to AFB_SESSION_LOA_EQ_0
AFB_SESSION_CLOSE	Closes the session after the reply and set the LOA to 0
AFB_SESSION_RENEW	Refreshes the token of authentification
AFB_SESSION_CHECK	Just requires the token authentification
AFB_SESSION_LOA_LE_0	Requires the current LOA to be lesser then or equal to 0
AFB_SESSION_LOA_LE_1	Requires the current LOA to be lesser then or equal to 1
AFB_SESSION_LOA_LE_2	Requires the current LOA to be lesser then or equal to 2
AFB_SESSION_LOA_LE_3	Requires the current LOA to be lesser then or equal to 3
AFB_SESSION_LOA_GE_0	Requires the current LOA to be greater then or equal to 0
AFB_SESSION_LOA_GE_1	Requires the current LOA to be greater then or equal to 1
AFB_SESSION_LOA_GE_2	Requires the current LOA to be greater then or equal to 2
AFB_SESSION_LOA_GE_3	Requires the current LOA to be greater then or equal to 3
AFB_SESSION_LOA_EQ_0	Requires the current LOA to be equal to 0
AFB_SESSION_LOA_EQ_1	Requires the current LOA to be equal to 1
AFB_SESSION_LOA_EQ_2	Requires the current LOA to be equal to 2
AFB_SESSION_LOA_EQ_3	Requires the current LOA to be equal to 3

If any of this flag is set, afb-daemon requires an authentication token as if AFB_SESSION_CHECK flag was also set.

The special value AFB_SESSION_NONE is zero and can be used to bypass token check.

+
Note that AFB_SESSION_CREATE and AFB_SESSION_CLOSE might be removed in later versions.
+

Sending messages to the log system

Afb-daemon provides 4 levels of verbosity and 5 methods for logging messages.

The verbosity is managed. Options allow the change the verbosity of afb-daemon and the verbosity of the bindings can be set binding by binding.

The methods for logging messages are defined as macros that test the verbosity level and that call the real logging function only if the message must be output. This avoid evaluation of arguments of the formatting messages if the message must not be output.

Verbs for logging messages

The 5 logging methods are:

Macro	Verbosity	Meaning	syslog level
ERROR	0	Error conditions	3
WARNING	1	Warning conditions	4
NOTICE	1	Normal but significant condition	5
INFO	2	Informational	6
DEBUG	3	Debug-level messages	7

You can note that the 2 methods WARNING and INFO have the same level of verbosity. But they don't have the same syslog level. It means that they are output with a different level on the logging system.

All of these methods have the same signature:

void ERROR(const struct afb_binding_interface *afbitf, const char *message, ...);

The first argument afbitf is the interface to afb daemon that the binding received at initialisation time when afbBindingV1Register is called.

The second argument message is a formatting string compatible with printf/sprintf.

The remaining arguments are arguments of the formating message like with printf.

Managing verbosity

Depending on the level of verbosity, the messages are output or not. The following table explains what messages will be output depending ont the verbosity level.

Level of verbosity	Outputed macro
0	ERROR
1	ERROR + WARNING + NOTICE
2	ERROR + WARNING + NOTICE + INFO
3	ERROR + WARNING + NOTICE + INFO + DEBUG

Output format and destination

The syslog level is used for forging a prefix to the message. The prefixes are:

syslog level	prefix
0	<0> EMERGENCY
1	<1> ALERT
2	<2> CRITICAL
3	<3> ERROR
4	<4> WARNING
5	<5> NOTICE
6	<6> INFO
7	<7> DEBUG

The message is pushed to standard error. The final destination of the message depends on how systemd service was configured through its variable StandardError. It can be journal, syslog or kmsg. (See man sd-daemon).

Sending events

Since version 0.5, bindings can broadcast events to any potential listener. As today only unattended even are supported. Targeted events are expected for next coming version.

The binding tic-tac-toe broadcasts events when the board changes. This is done in the function changed:

/*
+ * signals a change of the board
+ */
+static void changed(struct board *board, const char *reason)
+{
+    ...
+    struct json_object *description;
+
+    /* get the description */
+    description = describe(board);
+
+    ...
+
+    afb_daemon_broadcast_event(afbitf->daemon, reason, description);
+}

The description of the changed board is pushed via the daemon interface.

Within binding tic-tac-toe, reason indicates the origin of the change. In function afb_daemon_broadcast_event the second parameter is the name of broadcasted event. The third argument is the object that is transmitted with the event.

Function afb_daemon_broadcast_event is defined here after:

/*
+ * Broadcasts widely the event of 'name' with the data 'object'.
+ * 'object' can be NULL.
+ * 'daemon' MUST be the daemon given in interface when activating the binding.
+ *
+ * For conveniency, the function calls 'json_object_put' for 'object'.
+ * Thus, in the case where 'object' should remain available after
+ * the function returns, the function 'json_object_get' shall be used.
+ */
+void afb_daemon_broadcast_event(struct afb_daemon daemon, const char *name, struct json_object *object);

+
Be aware, as with reply functions object is automatically released using json_object_put when using this function. Call json_object_get before calling afb_daemon_broadcast_event to keep object available after function returns.
+

Event name received by listeners is prefixed with binding name. So when a change occurs after a move, the reason is move and every clients receive an event tictactoe/move.

+
Note that nothing is said about case sensitivity of event names. However, the event is always prefixed with the name that the binding declared, with the same case, followed with a slash /. Thus it is safe to compare event using a case sensitive comparison.
+

Writing an asynchronous method implementation

The tic-tac-toe example allows two clients or more to share the same board. This is implemented by the method join that illustrated partly how to retrieve arguments.

When two or more clients are sharing a same board, one of them can wait until the state of the board changes, but this could also be implemented using events because an even is generated each time the board changes.

In this case, the reply to the wait is sent only when the board changes. See the diagram below:

CLIENT A       CLIENT B         TIC-TAC-TOE
+   |              |                  |
+   +--------------|----------------->| wait . . . . . . . .
+   |              |                  |                     .
+   :              :                  :                      .
+   :              :                  :                      .
+   |              |                  |                      .
+   |              +----------------->| move . . .           .
+   |              |                  |          V           .
+   |              |<-----------------+ success of move      .
+   |              |                  |                    .
+   |<-------------|------------------+ success of wait  <

Here, this is an invocation of the binding by an other client that unblock the suspended wait call. Nevertheless in most case this should be a timer, a hardware event, a sync with a concurrent process or thread, ...

Common case of an asynchronous implementation.

Here is the listing of the function wait:

static void wait(struct afb_req req)
+{
+    struct board *board;
+    struct waiter *waiter;
+
+    /* retrieves the context for the session */
+    board = board_of_req(req);
+    INFO(afbitf, "method 'wait' called for boardid %d", board->id);
+
+    /* creates the waiter and enqueues it */
+    waiter = calloc(1, sizeof *waiter);
+    waiter->req = req;
+    waiter->next = board->waiters;
+    afb_req_addref(req);
+    board->waiters = waiter;
+}

After retrieving the board, the function adds a new waiter to waiters list and returns without setting a reply.

Before returning, it increases req request's reference count using afb_req_addref function.

+
When a method returns without setting a reply, it MUST increment request's reference count using afb_req_addref. If unpredictable behaviour may pop up.
+

Later, when a board changes, it calls tic-tac-toe changed function with reason of change in parameter.

Here is the full listing of the function changed:

/*
+ * signals a change of the board
+ */
+static void changed(struct board *board, const char *reason)
+{
+    struct waiter *waiter, *next;
+    struct json_object *description;
+
+    /* get the description */
+    description = describe(board);
+
+    waiter = board->waiters;
+    board->waiters = NULL;
+    while (waiter != NULL) {
+        next = waiter->next;
+        afb_req_success(waiter->req, json_object_get(description), reason);
+        afb_req_unref(waiter->req);
+        free(waiter);
+        waiter = next;
+    }
+
+    afb_event_sender_push(afb_daemon_get_event_sender(afbitf->daemon), reason, description);
+}

The list of waiters is walked and a reply is sent to each waiter. After sending the reply, the reference count of the request is decremented using afb_req_unref to allow resources to be freed.

+
The reference count MUST be decremented using afb_req_unref to free resources and avoid memory leaks. This usage count decrement should happen AFTER setting reply or bad things may happen.
+

How to build a binding

Afb-daemon provides a pkg-config configuration file that can be queried by providing afb-daemon in command line arguments. This configuration file provides data that should be used for bindings compilation. Examples:

$ pkg-config --cflags afb-daemon
+$ pkg-config --libs afb-daemon

Example for cmake meta build system

This example is the extract for building the binding afm-main using CMAKE.

pkg_check_modules(afb afb-daemon)
+if(afb_FOUND)
+    message(STATUS "Creation afm-main-binding for AFB-DAEMON")
+    add_library(afm-main-binding MODULE afm-main-binding.c)
+    target_compile_options(afm-main-binding PRIVATE ${afb_CFLAGS})
+    target_include_directories(afm-main-binding PRIVATE ${afb_INCLUDE_DIRS})
+    target_link_libraries(afm-main-binding utils ${afb_LIBRARIES})
+    set_target_properties(afm-main-binding PROPERTIES
+        PREFIX ""
+        LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-binding.export-map"
+    )
+    install(TARGETS afm-main-binding LIBRARY DESTINATION ${binding_dir})
+else()
+    message(STATUS "Not creating the binding for AFB-DAEMON")
+endif()

Let now describe some of these lines.

pkg_check_modules(afb afb-daemon)

This first lines searches to the pkg-config configuration file for afb-daemon. Resulting data are stored in the following variables:

Variable	Meaning
afb_FOUND	Set to 1 if afb-daemon binding development files exist
afb_LIBRARIES	Only the libraries (w/o the '-l') for compiling afb-daemon bindings
afb_LIBRARY_DIRS	The paths of the libraries (w/o the '-L') for compiling afb-daemon bindings
afb_LDFLAGS	All required linker flags for compiling afb-daemon bindings
afb_INCLUDE_DIRS	The '-I' preprocessor flags (w/o the '-I') for compiling afb-daemon bindings
afb_CFLAGS	All required cflags for compiling afb-daemon bindings

If development files are found, the binding can be added to the set of target to build.

add_library(afm-main-binding MODULE afm-main-binding.c)

This line asks to create a shared library having a single source file named afm-main-binding.c to be compiled. The default name of the created shared object is libafm-main-binding.so.

set_target_properties(afm-main-binding PROPERTIES
+    PREFIX ""
+    LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-binding.export-map"
+)

This lines are doing two things:

It renames the built library from libafm-main-binding.so to afm-main-binding.so by removing the implicitly added prefix lib. This step is not mandatory because afb-daemon doesn't check names of files at load time. The only filename convention used by afb-daemon relates to .so termination. *.so pattern is used when afb-daemon automatically discovers binding from a directory hierarchy.
It applies a version script at link time to only export the reserved name afbBindingV1Register for registration entry point. By default, when building a shared library linker exports all the public symbols (C functions that are not static).

Next line are:

target_include_directories(afm-main-binding PRIVATE ${afb_INCLUDE_DIRS})
+target_link_libraries(afm-main-binding utils ${afb_LIBRARIES})

As you can see it uses the variables computed by pkg_check_modules(afb afb-daemon) to configure the compiler and the linker.

Exporting the function afbBindingV1Register

The function afbBindingV1Register MUST be exported. This can be achieved using a version script at link time. Here after is a version script used for tic-tac-toe (bindings/samples/export.map).

{ global: afbBindingV1Register; local: *; };

This sample version script exports as global the symbol afbBindingV1Register and hides any other symbols.

This version script is added to the link options using the option --version-script=export.map is given directly to the linker or using the option -Wl,--version-script=export.map when the option is given to the C compiler.

Building within yocto

Adding a dependency to afb-daemon is enough. See below:

DEPENDS += " afb-daemon "

+#include +#include +#include +``` + +Header *afb/afb-binding.h* is the only hard dependency, it includes all features +that a binding MUST HAVE. Outside of includes used to support application logic, +common external headers used within bindings are: + +- *json-c/json.h*: should be include to handle json objects; +- *systemd/sd-event.h*: should be include to access event main loop; +- *systemd/sd-bus.h*: should be include for dbus connections. + +The *tictactoe* binding does not leverage systemd features, also only json.h +is used on top of mandatory afb/afb-binding.h. + +When including *afb/afb-binding.h*, the macro **_GNU_SOURCE** MUST be +defined. + +Choosing names +-------------- + +Designers of bindings should define a unique name for every API binding +as well as for methods VERBs. They should also define names for request +arguments passed as name/value pair in URI. + +While forging names, designers should respect few rules to +ensure that created names are valid and easy to use across platforms. + +All names and strings are UTF-8 encoded. + +### Names for API (binding) + +Binding API name are checked. +All characters are authorised except: + +- the control characters (\u0000 .. \u001f) +- the characters of the set { ' ', '"', '#', '%', '&', + '\'', '/', '?', '`', '\x7f' } + +In other words the set of forbidden characters is +{ \u0000..\u0020, \u0022, \u0023, \u0025..\u0027, + \u002f, \u003f, \u0060, \u007f }. + +Afb-daemon makes no distinction between lower case +and upper case when searching for API/VERB. + +### Names for methods + +The names of methods VERBs are totally free and not checked. + +However, the validity rules for method's VERB name are the +same as for Binding API name except that the dot(.) character +is forbidden. + +Afb-daemon makes no case distinction when searching for an API by name. + +### Names for arguments + +Argument's name are not restricted and can be everything you wish. + +> Warning arguments search is case sensitive and "index" and "Index" +> are not two different arguments. + +### Forging names widely available + +The key names of javascript object can be almost +anything using the arrayed notation: + + object[key] = value + +Nevertheless this is not the case with javascript dot notation: + + object.key = value + +Using the dot notation, the key must be a valid javascript +identifier and dash(-) as well as few other reserved characters cannot be used. + +For this reason, we advise developper to chose name compatible with both javascript and HTML notation. + +It is a good practice, even for arguments not to rely on case sensitivity. +This may reduce headache strength at debug time, especially with interpreted language like +javascript that may not warn you that a variable was not defined. + +Writing a synchronous method implementation +----------------------------------------- + +The method **tictactoe/board** is a synchronous implementation. +Here is its listing: + +```C +/* + * get the board + */ +static void board(struct afb_req req) +{ + struct board *board; + struct json_object *description; + + /* retrieves the context for the session */ + board = board_of_req(req); + INFO(afbitf, "method 'board' called for boardid %d", board->id); + + /* describe the board */ + description = describe(board); + + /* send the board's description */ + afb_req_success(req, description, NULL); +} +``` + +This example shows many aspects of a synchronous +method implementation. Let summarise it: + +1. The function **board_of_req** retrieves the context stored +for the binding: the board. + +2. The macro **INFO** sends a message of kind *INFO* +to the logging system. The global variable named **afbitf** +used represents the interface to afb-daemon. + +3. The function **describe** creates a json_object representing +the board. + +4. The function **afb_req_success** sends the reply, attaching to +it the object *description*. + +### The incoming request + +For any implementation, the request is received by a structure of type +**struct afb_req**. + +> Note that this is a PLAIN structure, not a pointer to a structure. + +The definition of **struct afb_req** is: + +```C +/* + * Describes the request by bindings from afb-daemon + */ +struct afb_req { + const struct afb_req_itf *itf; /* the interfacing functions */ + void *closure; /* the closure for functions */ +}; +``` + +It contains two pointers: first one *itf*, points to functions used +to handle internal request. Second one *closure* point onto function closure. + +> The structure must never be used directly. +> Instead developer should use the intended functions provided +> by afb-daemon as described here after. + +*req* is used to get arguments of the request, to send +answer, to store session data. + +This object and its interface is defined and documented +in the file names *afb/afb-req-itf.h* + +The above example uses twice *req* object request. + +The first time, to retrieve the board attached to the session of the request. + +The second time, to send the reply: an object that describes the current board. + +### Associating a client context to a session + +When *tic-tac-toe* binding receives a request, it musts get +the board describing the game associated to the session. + +For a binding, having data associated to a session is common. +This data is called "binding context" for the session. +Within *tic-tac-toe* binding the context is the board. + +Requests *afb_req* offer four functions for storing and retrieving session associated context. + +These functions are: + +- **afb_req_context_get**: + retrieves context data stored for current binding. + +- **afb_req_context_set**: + store context data of current binding. + +- **afb_req_context**: + if exist retrieves context data of current binding. + if context does not yet exist, creates a new context and store it. + +- **afb_req_context_clear**: + reset the stored context data. + +The binding *tictactoe* use a convenient function to retrieve +its context: the board. This function is *board_of_req*: + +```C +/* + * retrieves the board of the request + */ +static inline struct board *board_of_req(struct afb_req req) +{ + return afb_req_context(req, (void*)get_new_board, (void*)release_board); +} +``` + +The function **afb_req_context** ensures an existing context +for the session of the request. +Its two last arguments are functions to allocate and free context. +Note function type casts to avoid compilation warnings. + +Here is the definition of the function **afb_req_context** + +```C +/* + * Gets the pointer stored by the binding for the session of 'req'. + * If the stored pointer is NULL, indicating that no pointer was + * already stored, afb_req_context creates a new context by calling + * the function 'create_context' and stores it with the freeing function + * 'free_context'. + */ +static inline void *afb_req_context(struct afb_req req, void *(*create_context)(), void (*free_context)(void*)) +{ + void *result = afb_req_context_get(req); + if (result == NULL) { + result = create_context(); + afb_req_context_set(req, result, free_context); + } + return result; +} +``` + +The second argument if the function that creates the context. +For binding *tic-tac-toe* (function **get_new_board**). +The function **get_new_board** creates a new board and set usage its count to 1. +The boards are checking usage count to free resources when not used. + +The third argument is a function that frees context resources. +For binding *tic-tac-toe* (function **release_board**). +The function **release_board** decrease usage count of the board passed in argument. +When usage count falls to zero, data board are freed. + +Definition of other functions dealing with contexts: + +```C +/* + * Gets the pointer stored by the binding for the session of 'req'. + * When the binding has not yet recorded a pointer, NULL is returned. + */ +void *afb_req_context_get(struct afb_req req); + +/* + * Stores for the binding the pointer 'context' to the session of 'req'. + * The function 'free_context' will be called when the session is closed + * or if binding stores an other pointer. + */ +void afb_req_context_set(struct afb_req req, void *context, void (*free_context)(void*)); + +/* + * Frees the pointer stored by the binding for the session of 'req' + * and sets it to NULL. + * + * Shortcut for: afb_req_context_set(req, NULL, NULL) + */ +static inline void afb_req_context_clear(struct afb_req req) +{ + afb_req_context_set(req, NULL, NULL); +} +``` + +### Sending reply to a request + +Two kinds of replies: successful or failure. + +> Sending a reply to a request MUST be done once and only once. + +It exists two functions for "success" replies: **afb_req_success** and **afb_req_success_f**. + +```C +/* + * Sends a reply of kind success to the request 'req'. + * The status of the reply is automatically set to "success". + * Its send the object 'obj' (can be NULL) with an + * informationnal comment 'info (can also be NULL). + * + * For conveniency, the function calls 'json_object_put' for 'obj'. + * Thus, in the case where 'obj' should remain available after + * the function returns, the function 'json_object_get' shall be used. + */ +void afb_req_success(struct afb_req req, struct json_object *obj, const char *info); + +/* + * Same as 'afb_req_success' but the 'info' is a formatting + * string followed by arguments. + * + * For conveniency, the function calls 'json_object_put' for 'obj'. + * Thus, in the case where 'obj' should remain available after + * the function returns, the function 'json_object_get' shall be used. + */ +void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...); +``` + +It exists two functions for "failure" replies: **afb_req_fail** and **afb_req_fail_f**. + +```C +/* + * Sends a reply of kind failure to the request 'req'. + * The status of the reply is set to 'status' and an + * informational comment 'info' (can also be NULL) can be added. + * + * Note that calling afb_req_fail("success", info) is equivalent + * to call afb_req_success(NULL, info). Thus even if possible it + * is strongly recommended to NEVER use "success" for status. + * + * For conveniency, the function calls 'json_object_put' for 'obj'. + * Thus, in the case where 'obj' should remain available after + * the function returns, the function 'json_object_get' shall be used. + */ +void afb_req_fail(struct afb_req req, const char *status, const char *info); + +/* + * Same as 'afb_req_fail' but the 'info' is a formatting + * string followed by arguments. + * + * For conveniency, the function calls 'json_object_put' for 'obj'. + * Thus, in the case where 'obj' should remain available after + * the function returns, the function 'json_object_get' shall be used. + */ +void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...); +``` + +> For conveniency, these functions automatically call **json_object_put** to release **obj**. +> Because **obj** usage count is null after being passed to a reply function, it SHOULD not be used anymore. +> If exceptionally **obj** needs to remain usable after reply function then using **json_object_get** on **obj** +> to increase usage count and cancels the effect the **json_object_put** is possible. + +Getting argument of invocation +------------------------------ + +Many methods expect arguments. Afb-daemon's bindings +retrieve arguments by name and not by position. + +Arguments are passed by requests through either HTTP +or WebSockets. + +For example, the method **join** of binding **tic-tac-toe** +expects one argument: the *boardid* to join. Here is an extract: + +```C +/* + * Join a board + */ +static void join(struct afb_req req) +{ + struct board *board, *new_board; + const char *id; + + /* retrieves the context for the session */ + board = board_of_req(req); + INFO(afbitf, "method 'join' called for boardid %d", board->id); + + /* retrieves the argument */ + id = afb_req_value(req, "boardid"); + if (id == NULL) + goto bad_request; + ... +``` + +The function **afb_req_value** searches in the request *req* +for argument name passed in the second argument. When argument name +is not passed, **afb_req_value** returns NULL. + +> The search is case sensitive and *boardid* is not equivalent to *BoardId*. +> Nevertheless having argument names that only differ by name case is not a good idea. + +### Basic functions for querying arguments + +The function **afb_req_value** is defined here after: + +```C +/* + * Gets from the request 'req' the string value of the argument of 'name'. + * Returns NULL if when there is no argument of 'name'. + * Returns the value of the argument of 'name' otherwise. + * + * Shortcut for: afb_req_get(req, name).value + */ +static inline const char *afb_req_value(struct afb_req req, const char *name) +{ + return afb_req_get(req, name).value; +} +``` + +It is defined as a shortcut to call the function **afb_req_get**. +That function is defined here after: + +```C +/* + * Gets from the request 'req' the argument of 'name'. + * Returns a PLAIN structure of type 'struct afb_arg'. + * When the argument of 'name' is not found, all fields of result are set to NULL. + * When the argument of 'name' is found, the fields are filled, + * in particular, the field 'result.name' is set to 'name'. + * + * There is a special name value: the empty string. + * The argument of name "" is defined only if the request was made using + * an HTTP POST of Content-Type "application/json". In that case, the + * argument of name "" receives the value of the body of the HTTP request. + */ +struct afb_arg afb_req_get(struct afb_req req, const char *name); +``` + +That function takes 2 parameters: the request and the name +of the argument to retrieve. It returns a PLAIN structure of +type **struct afb_arg**. + +There is a special name that is defined when the request is +of type HTTP/POST with a Content-Type being application/json. +This name is **""** (the empty string). In that case, the value +of this argument of empty name is the string received as a body +of the post and is supposed to be a JSON string. + +The definition of **struct afb_arg** is: + +```C +/* + * Describes an argument (or parameter) of a request + */ +struct afb_arg { + const char *name; /* name of the argument or NULL if invalid */ + const char *value; /* string representation of the value of the argument */ + /* original filename of the argument if path != NULL */ + const char *path; /* if not NULL, path of the received file for the argument */ + /* when the request is finalized this file is removed */ +}; +``` + +The structure returns the data arguments that are known for the +request. This data include a field named **path**. This **path** +can be accessed using the function **afb_req_path** defined here after: + +```C +/* + * Gets from the request 'req' the path for file attached to the argument of 'name'. + * Returns NULL if when there is no argument of 'name' or when there is no file. + * Returns the path of the argument of 'name' otherwise. + * + * Shortcut for: afb_req_get(req, name).path + */ +static inline const char *afb_req_path(struct afb_req req, const char *name) +{ + return afb_req_get(req, name).path; +} +``` + +The path is only defined for HTTP/POST requests that send file. + +### Arguments for received files + +As it is explained above, clients can send files using HTTP/POST requests. + +Received files are attached to "file" argument name. For example, the +following HTTP fragment (from test/sample-post.html) +will send an HTTP/POST request to the method +**post/upload-image** with 2 arguments named *file* and +*hidden*. + +```html +

Sample Post File

+ +``` + +Argument named **file** should have both its value and path defined. + +The value is the name of the file as it was set by the HTTP client. +Generally it is the filename on client side. + +The path is the effective path of saved file on the temporary local storage +area of the application. This is a randomly generated and unique filename. +It is not linked with the original filename as used on client side. + +After success the binding can use the uploaded file directly from local storage path with no restriction: +read, write, remove, copy, rename... +Nevertheless when request reply is set and query terminated, the uploaded temporary file at +path is destroyed. + +### Arguments as a JSON object + +Bindings may also request every arguments of a given call as one single object. +This feature is provided by the function **afb_req_json** defined here after: + +```C +/* + * Gets from the request 'req' the json object hashing the arguments. + * The returned object must not be released using 'json_object_put'. + */ +struct json_object *afb_req_json(struct afb_req req); +``` + +It returns a json object. This object depends on how the request was built: + +- For HTTP requests, this json object uses key names mapped on argument name. +Values are either string for common arguments or object ie: { "file": "...", "path": "..." } + +- For WebSockets requests, returned directly the object as provided by the client. + +> In fact, for Websockets requests, the function **afb_req_value** +> can be seen as a shortcut to +> ***json_object_get_string(json_object_object_get(afb_req_json(req), name))*** + +Initialisation of the binding and declaration of methods +----------------------------------------------------- + +To be active, binding's methods should be declared to +afb-daemon. Furthermore, the binding itself must be recorded. + +The registration mechanism is very basic: when afb-need starts, +it loads all bindings listed in: command line or configuration file. + +Loading a binding follows the following steps: + +1. Afb-daemon loads the binding with *dlopen*. + +2. Afb-daemon searches for a symbol named **afbBindingV1Register** using *dlsym*. +This symbol is assumed to be the exported initialisation function of the binding. + +3. Afb-daemon builds an interface object for the binding. + +4. Afb-daemon calls the found function **afbBindingV1Register** with interface pointer +as parameter. + +5. Function **afbBindingV1Register** setups the binding and initialises it. + +6. Function **afbBindingV1Register** returns the pointer to a structure +describing the binding: version, name (prefix or API name), and list of methods. + +7. Afb-daemon checks that the returned version and name can be managed. +If so, binding and its methods are register to become usable as soon as +afb-daemon initialisation is finished. + +Here after the code used for **afbBindingV1Register** from binding *tic-tac-toe*: + +```C +/* + * activation function for registering the binding called by afb-daemon + */ +const struct afb_binding *afbBindingV1Register(const struct afb_binding_interface *itf) +{ + afbitf = itf; // records the interface for accessing afb-daemon + return &binding_description; // returns the description of the binding +} +``` + +It is a very minimal initialisation function because *tic-tac-toe* binding doesn't +have any application related initialisation step. It merely record daemon's interface +and returns its description. + +The variable **afbitf** is a binding global variable. It keeps the +interface to afb-daemon that should be used for logging and pushing events. +Here is its declaration: + +```C +/* + * the interface to afb-daemon + */ +const struct afb_binding_interface *afbitf; +``` + +The description of the binding is defined here after. + +```C +/* + * array of the methods exported to afb-daemon + */ +static const struct afb_verb_desc_v1 binding_methods[] = { + /* VERB'S NAME SESSION MANAGEMENT FUNCTION TO CALL SHORT DESCRIPTION */ + { .name= "new", .session= AFB_SESSION_NONE, .callback= new, .info= "Starts a new game" }, + { .name= "play", .session= AFB_SESSION_NONE, .callback= play, .info= "Asks the server to play" }, + { .name= "move", .session= AFB_SESSION_NONE, .callback= move, .info= "Tells the client move" }, + { .name= "board", .session= AFB_SESSION_NONE, .callback= board, .info= "Get the current board" }, + { .name= "level", .session= AFB_SESSION_NONE, .callback= level, .info= "Set the server level" }, + { .name= "join", .session= AFB_SESSION_CHECK,.callback= join, .info= "Join a board" }, + { .name= "undo", .session= AFB_SESSION_NONE, .callback= undo, .info= "Undo the last move" }, + { .name= "wait", .session= AFB_SESSION_NONE, .callback= wait, .info= "Wait for a change" }, + { .name= NULL } /* marker for end of the array */ +}; + +/* + * description of the binding for afb-daemon + */ +static const struct afb_binding binding_description = +{ + /* description conforms to VERSION 1 */ + .type= AFB_BINDING_VERSION_1, + .v1= { /* fills the v1 field of the union when AFB_BINDING_VERSION_1 */ + .prefix= "tictactoe", /* the API name (or binding name or prefix) */ + .info= "Sample tac-tac-toe game", /* short description of of the binding */ + .methods = binding_methods /* the array describing the methods of the API */ + } +}; +``` + +The structure **binding_description** describes the binding. +It declares the type and version of the binding, its name, a short description +and its methods list. + +The list of methods is an array of structures describing the methods and terminated by a NULL marker. + +In version one of afb-damon binding, a method description contains 4 fields: + +- the name of the method, + +- the session management flags, + +- the implementation function to be call for the method, + +- a short description. + +The structure describing methods is defined as follows: + +```C +/* + * Description of one method of the API provided by the binding + * This enumeration is valid for bindings of type 1 + */ +struct afb_verb_desc_v1 +{ + const char *name; /* name of the method */ + enum AFB_session_v1 session; /* authorisation and session requirements of the method */ + void (*callback)(struct afb_req req); /* callback function implementing the method */ + const char *info; /* textual description of the method */ +}; +``` + +For technical reasons, the enumeration **enum AFB_session_v1** is not exactly an +enumeration but the wrapper of constant definitions that can be mixed using bitwise or +(the C operator |). + +The constants that can bit mixed are: + +Constant name | Meaning +-------------------------|------------------------------------------------------------- +**AFB_SESSION_CREATE** | Equals to AFB_SESSION_LOA_EQ_0|AFB_SESSION_RENEW +**AFB_SESSION_CLOSE** | Closes the session after the reply and set the LOA to 0 +**AFB_SESSION_RENEW** | Refreshes the token of authentification +**AFB_SESSION_CHECK** | Just requires the token authentification +**AFB_SESSION_LOA_LE_0** | Requires the current LOA to be lesser then or equal to 0 +**AFB_SESSION_LOA_LE_1** | Requires the current LOA to be lesser then or equal to 1 +**AFB_SESSION_LOA_LE_2** | Requires the current LOA to be lesser then or equal to 2 +**AFB_SESSION_LOA_LE_3** | Requires the current LOA to be lesser then or equal to 3 +**AFB_SESSION_LOA_GE_0** | Requires the current LOA to be greater then or equal to 0 +**AFB_SESSION_LOA_GE_1** | Requires the current LOA to be greater then or equal to 1 +**AFB_SESSION_LOA_GE_2** | Requires the current LOA to be greater then or equal to 2 +**AFB_SESSION_LOA_GE_3** | Requires the current LOA to be greater then or equal to 3 +**AFB_SESSION_LOA_EQ_0** | Requires the current LOA to be equal to 0 +**AFB_SESSION_LOA_EQ_1** | Requires the current LOA to be equal to 1 +**AFB_SESSION_LOA_EQ_2** | Requires the current LOA to be equal to 2 +**AFB_SESSION_LOA_EQ_3** | Requires the current LOA to be equal to 3 + +If any of this flag is set, afb-daemon requires an authentication token +as if **AFB_SESSION_CHECK** flag was also set. + +The special value **AFB_SESSION_NONE** is zero and can be used to bypass token check. + +> Note that **AFB_SESSION_CREATE** and **AFB_SESSION_CLOSE** might be removed in later versions. + +Sending messages to the log system +---------------------------------- + +Afb-daemon provides 4 levels of verbosity and 5 methods for logging messages. + +The verbosity is managed. Options allow the change the verbosity of afb-daemon +and the verbosity of the bindings can be set binding by binding. + +The methods for logging messages are defined as macros that test the +verbosity level and that call the real logging function only if the +message must be output. This avoid evaluation of arguments of the +formatting messages if the message must not be output. + +### Verbs for logging messages + +The 5 logging methods are: + +Macro | Verbosity | Meaning | syslog level +--------|:---------:|-----------------------------------|:-----------: +ERROR | 0 | Error conditions | 3 +WARNING | 1 | Warning conditions | 4 +NOTICE | 1 | Normal but significant condition | 5 +INFO | 2 | Informational | 6 +DEBUG | 3 | Debug-level messages | 7 + +You can note that the 2 methods **WARNING** and **INFO** have the same level +of verbosity. But they don't have the same *syslog level*. It means that +they are output with a different level on the logging system. + +All of these methods have the same signature: + +```C +void ERROR(const struct afb_binding_interface *afbitf, const char *message, ...); +``` + +The first argument **afbitf** is the interface to afb daemon that the +binding received at initialisation time when **afbBindingV1Register** is called. + +The second argument **message** is a formatting string compatible with printf/sprintf. + +The remaining arguments are arguments of the formating message like with printf. + +### Managing verbosity + +Depending on the level of verbosity, the messages are output or not. +The following table explains what messages will be output depending +ont the verbosity level. + +Level of verbosity | Outputed macro +:-----------------:|-------------------------- +0 | ERROR +1 | ERROR + WARNING + NOTICE +2 | ERROR + WARNING + NOTICE + INFO +3 | ERROR + WARNING + NOTICE + INFO + DEBUG + +### Output format and destination + +The syslog level is used for forging a prefix to the message. +The prefixes are: + +syslog level | prefix +:-----------:|--------------- +0 | <0> EMERGENCY +1 | <1> ALERT +2 | <2> CRITICAL +3 | <3> ERROR +4 | <4> WARNING +5 | <5> NOTICE +6 | <6> INFO +7 | <7> DEBUG + + +The message is pushed to standard error. +The final destination of the message depends on how systemd service +was configured through its variable **StandardError**. It can be +journal, syslog or kmsg. (See man sd-daemon). + +Sending events +-------------- + +Since version 0.5, bindings can broadcast events to any potential listener. +As today only unattended even are supported. Targeted events are expected for next +coming version. + +The binding *tic-tac-toe* broadcasts events when the board changes. +This is done in the function **changed**: + +```C +/* + * signals a change of the board + */ +static void changed(struct board *board, const char *reason) +{ + ... + struct json_object *description; + + /* get the description */ + description = describe(board); + + ... + + afb_daemon_broadcast_event(afbitf->daemon, reason, description); +} +``` + +The description of the changed board is pushed via the daemon interface. + +Within binding *tic-tac-toe*, *reason* indicates the origin of +the change. In function **afb_daemon_broadcast_event** the second +parameter is the name of broadcasted event. The third argument is the +object that is transmitted with the event. + +Function **afb_daemon_broadcast_event** is defined here after: + +```C +/* + * Broadcasts widely the event of 'name' with the data 'object'. + * 'object' can be NULL. + * 'daemon' MUST be the daemon given in interface when activating the binding. + * + * For conveniency, the function calls 'json_object_put' for 'object'. + * Thus, in the case where 'object' should remain available after + * the function returns, the function 'json_object_get' shall be used. + */ +void afb_daemon_broadcast_event(struct afb_daemon daemon, const char *name, struct json_object *object); +``` + +> Be aware, as with reply functions **object** is automatically released using +> **json_object_put** when using this function. Call **json_object_get** before +> calling **afb_daemon_broadcast_event** to keep **object** available +> after function returns. + +Event name received by listeners is prefixed with binding name. +So when a change occurs after a move, the reason is **move** and every clients +receive an event **tictactoe/move**. + +> Note that nothing is said about case sensitivity of event names. +> However, the event is always prefixed with the name that the binding +> declared, with the same case, followed with a slash /. +> Thus it is safe to compare event using a case sensitive comparison. + + + +Writing an asynchronous method implementation +------------------------------------------- + +The *tic-tac-toe* example allows two clients or more to share the same board. +This is implemented by the method **join** that illustrated partly how to +retrieve arguments. + +When two or more clients are sharing a same board, one of them can wait +until the state of the board changes, but this could also be implemented using +events because an even is generated each time the board changes. + +In this case, the reply to the wait is sent only when the board changes. +See the diagram below: + + CLIENT A CLIENT B TIC-TAC-TOE + | | | + +--------------|----------------->| wait . . . . . . . . + | | | . + : : : . + : : : . + | | | . + | +----------------->| move . . . . + | | | V . + | |<-----------------+ success of move . + | | | . + |<-------------|------------------+ success of wait < + +Here, this is an invocation of the binding by an other client that +unblock the suspended *wait* call. +Nevertheless in most case this should be a timer, a hardware event, a sync with +a concurrent process or thread, ... + +Common case of an asynchronous implementation. + +Here is the listing of the function **wait**: + +```C +static void wait(struct afb_req req) +{ + struct board *board; + struct waiter *waiter; + + /* retrieves the context for the session */ + board = board_of_req(req); + INFO(afbitf, "method 'wait' called for boardid %d", board->id); + + /* creates the waiter and enqueues it */ + waiter = calloc(1, sizeof *waiter); + waiter->req = req; + waiter->next = board->waiters; + afb_req_addref(req); + board->waiters = waiter; +} +``` + +After retrieving the board, the function adds a new waiter to +waiters list and returns without setting a reply. + +Before returning, it increases **req** request's reference count using **afb_req_addref** function. + +> When a method returns without setting a reply, +> it **MUST** increment request's reference count +> using **afb_req_addref**. If unpredictable behaviour may pop up. + +Later, when a board changes, it calls *tic-tac-toe* **changed** function +with reason of change in parameter. + +Here is the full listing of the function **changed**: + +```C +/* + * signals a change of the board + */ +static void changed(struct board *board, const char *reason) +{ + struct waiter *waiter, *next; + struct json_object *description; + + /* get the description */ + description = describe(board); + + waiter = board->waiters; + board->waiters = NULL; + while (waiter != NULL) { + next = waiter->next; + afb_req_success(waiter->req, json_object_get(description), reason); + afb_req_unref(waiter->req); + free(waiter); + waiter = next; + } + + afb_event_sender_push(afb_daemon_get_event_sender(afbitf->daemon), reason, description); +} +``` + +The list of waiters is walked and a reply is sent to each waiter. +After sending the reply, the reference count of the request +is decremented using **afb_req_unref** to allow resources to be freed. + +> The reference count **MUST** be decremented using **afb_req_unref** to free +> resources and avoid memory leaks. +> This usage count decrement should happen **AFTER** setting reply or +> bad things may happen. + +How to build a binding +--------------------- + +Afb-daemon provides a *pkg-config* configuration file that can be +queried by providing **afb-daemon** in command line arguments. +This configuration file provides data that should be used +for bindings compilation. Examples: + +```bash +$ pkg-config --cflags afb-daemon +$ pkg-config --libs afb-daemon +``` + +### Example for cmake meta build system + +This example is the extract for building the binding *afm-main* using *CMAKE*. + +```cmake +pkg_check_modules(afb afb-daemon) +if(afb_FOUND) + message(STATUS "Creation afm-main-binding for AFB-DAEMON") + add_library(afm-main-binding MODULE afm-main-binding.c) + target_compile_options(afm-main-binding PRIVATE ${afb_CFLAGS}) + target_include_directories(afm-main-binding PRIVATE ${afb_INCLUDE_DIRS}) + target_link_libraries(afm-main-binding utils ${afb_LIBRARIES}) + set_target_properties(afm-main-binding PROPERTIES + PREFIX "" + LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-binding.export-map" + ) + install(TARGETS afm-main-binding LIBRARY DESTINATION ${binding_dir}) +else() + message(STATUS "Not creating the binding for AFB-DAEMON") +endif() +``` + +Let now describe some of these lines. + +```cmake +pkg_check_modules(afb afb-daemon) +``` + +This first lines searches to the *pkg-config* configuration file for +**afb-daemon**. Resulting data are stored in the following variables: + +Variable | Meaning +------------------|------------------------------------------------ +afb_FOUND | Set to 1 if afb-daemon binding development files exist +afb_LIBRARIES | Only the libraries (w/o the '-l') for compiling afb-daemon bindings +afb_LIBRARY_DIRS | The paths of the libraries (w/o the '-L') for compiling afb-daemon bindings +afb_LDFLAGS | All required linker flags for compiling afb-daemon bindings +afb_INCLUDE_DIRS | The '-I' preprocessor flags (w/o the '-I') for compiling afb-daemon bindings +afb_CFLAGS | All required cflags for compiling afb-daemon bindings + +If development files are found, the binding can be added to the set of +target to build. + +```cmake +add_library(afm-main-binding MODULE afm-main-binding.c) +``` + +This line asks to create a shared library having a single +source file named afm-main-binding.c to be compiled. +The default name of the created shared object is +**libafm-main-binding.so**. + +```cmake +set_target_properties(afm-main-binding PROPERTIES + PREFIX "" + LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-binding.export-map" +) +``` + +This lines are doing two things: + +1. It renames the built library from **libafm-main-binding.so** to **afm-main-binding.so** +by removing the implicitly added prefix *lib*. This step is not mandatory +because afb-daemon doesn't check names of files at load time. +The only filename convention used by afb-daemon relates to **.so** termination. +*.so pattern is used when afb-daemon automatically discovers binding from a directory hierarchy. + +2. It applies a version script at link time to only export the reserved name +**afbBindingV1Register** for registration entry point. By default, when building +a shared library linker exports all the public symbols (C functions that are not **static**). + +Next line are: + +```cmake +target_include_directories(afm-main-binding PRIVATE ${afb_INCLUDE_DIRS}) +target_link_libraries(afm-main-binding utils ${afb_LIBRARIES}) +``` + +As you can see it uses the variables computed by ***pkg_check_modules(afb afb-daemon)*** +to configure the compiler and the linker. + +### Exporting the function afbBindingV1Register + +The function **afbBindingV1Register** MUST be exported. This can be achieved +using a version script at link time. Here after is a version script used for +*tic-tac-toe* (bindings/samples/export.map). + + { global: afbBindingV1Register; local: *; }; + +This sample [version script](https://sourceware.org/binutils/docs-2.26/ld/VERSION.html#VERSION) +exports as global the symbol *afbBindingV1Register* and hides any +other symbols. + +This version script is added to the link options using the +option **--version-script=export.map** is given directly to the +linker or using the option **-Wl,--version-script=export.map** +when the option is given to the C compiler. + +### Building within yocto + +Adding a dependency to afb-daemon is enough. See below: + + DEPENDS += " afb-daemon " + diff --git a/doc/afb-daemon-vocabulary.html b/doc/afb-daemon-vocabulary.html index d2d4f512..bffe91f6 100644 --- a/doc/afb-daemon-vocabulary.html +++ b/doc/afb-daemon-vocabulary.html @@ -16,11 +16,12 @@

Vocabulary for AFB-DAEMON

José Bollo

27 mai 2016

23 juin 2016

Vocabulary for AFB-DAEMON
- Binding
- Event
- Level of assurance (LOA)
- Plugin

Adding native features to HTML5/QML applications

Applications can provide with their packaged delivery a plugin. That plugin will be instanciated for each application instance. The methods of the plugin will be accessible by applications and will be excuted within the security context.

Applications can provide with their packaged delivery a binding. That binding will be instanciated for each application instance. The methods of the binding will be accessible by applications and will be excuted within the security context.

Offering services to the system

It is possible to run the binder afb-daemon as a daemon that provides the API of its plugins.

It is possible to run the binder afb-daemon as a daemon that provides the API of its bindings.

This will be used for:

offering common APIs

For this case, the binder afb-daemon takes care to attribute one single session context to each client instance. It allows plugins to store and retrieve data associated to each of its client.

The plugins of the binder afb-daemon

The binder can instanciate plugins. The primary use of plugins is to add native methods that can be accessed by applications written with any language through web technologies ala JSON RPC.

For this case, the binder afb-daemon takes care to attribute one single session context to each client instance. It allows bindings to store and retrieve data associated to each of its client.

The bindings of the binder afb-daemon

The binder can instanciate bindings. The primary use of bindings is to add native methods that can be accessed by applications written with any language through web technologies ala JSON RPC.

This simple idea is declined to serves multiple purposes:

add native feature to applications
add common API available by any applications
provide customers services

A specific document explains how to write an afb-daemon binder plugin: HOWTO WRITE a PLUGIN for AFB-DAEMON

A specific document explains how to write an afb-daemon binder binding: HOWTO WRITE a BINDING for AFB-DAEMON

Launching the binder afb-daemon

The launch options for binder afb-daemon are:

  --help
@@ -209,7 +209,7 @@ Figure: binder afb-daemon for services
 
     HTML Root API URL [default /api]
 
-    The plugins are available within that url.
+    The bindings are available within that url.
 
   --alias=xxxx
 
@@ -224,7 +224,7 @@ Figure: binder afb-daemon for services
 
   --apitimeout=xxxx
 
-    Plugin API timeout in seconds [default 20]
+    binding API timeout in seconds [default 20]
 
     Defines how many seconds maximum a method is allowed to run.
     0 means no limit.
@@ -247,19 +247,19 @@ Figure: binder afb-daemon for services
 
   --ldpaths=xxxx
 
-    Load Plugins from given paths separated by colons
-    as for dir1:dir2:plugin1.so:... [default = $libdir/afb]
+    Load bindings from given paths separated by colons
+    as for dir1:dir2:binding1.so:... [default = $libdir/afb]
 
-    You can mix path to directories and to plugins.
+    You can mix path to directories and to bindings.
     The sub-directories of the given directories are searched
     recursively.
 
-    The plugins are the files terminated by '.so' (the extension
+    The bindings are the files terminated by '.so' (the extension
     so denotes shared object) that contain the public entry symbol.
 
-  --plugin=xxxx
+  --binding=xxxx
 
-    Load the plugin of given path.
+    Load the binding of given path.
 
   --token=xxxx
 
@@ -294,7 +294,7 @@ Figure: binder afb-daemon for services
 
     Provides a binder afb-daemon service through dbus.
 
-    The name xxxx must be the name of an API defined by a plugin.
+    The name xxxx must be the name of an API defined by a binding.
     This API is exported through DBUS.
 
   --foreground
diff --git a/doc/afb-overview.md b/doc/afb-overview.md
index 1bd83240..ab24606c 100644
--- a/doc/afb-overview.md
+++ b/doc/afb-overview.md
@@ -34,7 +34,7 @@ of afb-daemon:
 	.   +-------------------+----------------------+  .
 	.   |                            :             |  .
 	.   |        b i n d e r         :             |  .
-	.   |    A F B - D A E M O N     :   PLUGINS   |  .
+	.   |    A F B - D A E M O N     :  BINDINGS   |  .
 	.   |                            :             |  .
 	.   +-------------------+----------------------+  .
 	.                       |                         .
@@ -97,7 +97,7 @@ when the application is run remotely:
 	.                           |                           .
 	.       +-------------------+----------------------+    .
 	.       |                            :             |    .
-	.       |    A F B - D A E M O N     :   PLUGINS   |    .
+	.       |    A F B - D A E M O N     :   BINDINGS  |    .
 	.       |                            :             |    .
 	.       +-------------------+----------------------+    .
 	.                           |                           .
@@ -108,15 +108,15 @@ when the application is run remotely:
 
 ### Adding native features to HTML5/QML applications
 
-Applications can provide with their packaged delivery a plugin.
-That plugin will be instanciated for each application instance.
-The methods of the plugin will be accessible by applications and
+Applications can provide with their packaged delivery a binding.
+That binding will be instanciated for each application instance.
+The methods of the binding will be accessible by applications and
 will be excuted within the security context.
 
 ### Offering services to the system
 
 It is possible to run the binder afb-daemon as a daemon that provides the
-API of its plugins.
+API of its bindings.
 
 This will be used for:
 
@@ -141,7 +141,7 @@ In that case, the figure showing the whole aspects is
 	. +-----------------+------------------+  .     . +------------------------------------+  .
 	. |                        :           |  .     . |                        :           |  .
 	. |      b i n d e r       :           |  .     . |      b i n d e r       :  service  |  .
-	. |  A F B - D A E M O N   :  PLUGINS  |  .     . |  A F B - D A E M O N   :  PLUGINS  |  .
+	. |  A F B - D A E M O N   : BINDINGS  |  .     . |  A F B - D A E M O N   : BINDINGS  |  .
 	. |                        :           |  .     . |                        :     A     |  .
 	. +-----------------+------------------+  .     . +-----------------+------------------+  .
 	.                   |                     .     .                   |                     .
@@ -158,7 +158,7 @@ In that case, the figure showing the whole aspects is
 	. +-----------------+------------------+  .     . +-----------------+------------------+  .
 	. |                        :           |  .     . |                        :           |  .
 	. |      b i n d e r       :  service  |  .     . |      b i n d e r       :  service  |  .
-	. |  A F B - D A E M O N   :  PLUGINS  |  .     . |  A F B - D A E M O N   :  PLUGINS  |  .
+	. |  A F B - D A E M O N   : BINDINGS  |  .     . |  A F B - D A E M O N   : BINDINGS  |  .
 	. |                        :     B     |  .     . |                        :     C     |  .
 	. +------------------------------------+  .     . +------------------------------------+  .
 	.                                         .     .                                         .
@@ -167,13 +167,13 @@ In that case, the figure showing the whole aspects is
 
 
 For this case, the binder afb-daemon takes care to attribute one single session
-context to each client instance. It allows plugins to store and retrieve data
+context to each client instance. It allows bindings to store and retrieve data
 associated to each of its client.
 
-The plugins of the binder afb-daemon
+The bindings of the binder afb-daemon
 ------------------------------------
 
-The binder can instanciate plugins. The primary use of plugins
+The binder can instanciate bindings. The primary use of bindings
 is to add native methods that can be accessed by applications
 written with any language through web technologies ala JSON RPC.
 
@@ -185,8 +185,8 @@ This simple idea is declined to serves multiple purposes:
 
 3. provide customers services
 
-A specific document explains how to write an afb-daemon binder plugin:
-[HOWTO WRITE a PLUGIN for AFB-DAEMON](afb-plugin-writing.html)
+A specific document explains how to write an afb-daemon binder binding:
+[HOWTO WRITE a BINDING for AFB-DAEMON](afb-binding-writing.html)
 
 
 Launching the binder afb-daemon
@@ -226,7 +226,7 @@ The launch options for binder **afb-daemon** are:
 
 		HTML Root API URL [default /api]
 
-		The plugins are available within that url.
+		The bindings are available within that url.
 
 	  --alias=xxxx
 
@@ -241,7 +241,7 @@ The launch options for binder **afb-daemon** are:
 
 	  --apitimeout=xxxx
 
-		Plugin API timeout in seconds [default 20]
+		binding API timeout in seconds [default 20]
 
 		Defines how many seconds maximum a method is allowed to run.
 		0 means no limit.
@@ -264,19 +264,19 @@ The launch options for binder **afb-daemon** are:
 
 	  --ldpaths=xxxx
 
-		Load Plugins from given paths separated by colons
-		as for dir1:dir2:plugin1.so:... [default = $libdir/afb]
+		Load bindings from given paths separated by colons
+		as for dir1:dir2:binding1.so:... [default = $libdir/afb]
 
-		You can mix path to directories and to plugins.
+		You can mix path to directories and to bindings.
 		The sub-directories of the given directories are searched
 		recursively.
 
-		The plugins are the files terminated by '.so' (the extension
+		The bindings are the files terminated by '.so' (the extension
 		so denotes shared object) that contain the public entry symbol.
 
-	  --plugin=xxxx
+	  --binding=xxxx
 
-		Load the plugin of given path.
+		Load the binding of given path.
 
 	  --token=xxxx
 
@@ -311,7 +311,7 @@ The launch options for binder **afb-daemon** are:
 
 		Provides a binder afb-daemon service through dbus.
 
-		The name xxxx must be the name of an API defined by a plugin.
+		The name xxxx must be the name of an API defined by a binding.
 		This API is exported through DBUS.
 
 	  --foreground
diff --git a/doc/afb-plugin-writing.html b/doc/afb-plugin-writing.html
deleted file mode 100644
index 6c866fb6..00000000
--- a/doc/afb-plugin-writing.html
+++ /dev/null
@@ -1,953 +0,0 @@
-
-
-
-  
-  
-  
-  
-  
-  HOWTO WRITE a PLUGIN for AFB-DAEMON
-  
-  
-  
-  
-
-
-
-HOWTO WRITE a PLUGIN for AFB-DAEMON
-José Bollo
-Fulup Ar Foll
-09 juin 2016
-
-
-
-HOWTO WRITE a PLUGIN for AFB-DAEMON
-Summary
-Nature of a plugin
-Class of plugins
-Live cycle of plugins within afb-daemon
-Plugin Contend
-
-The Tic-Tac-Toe example
-Dependencies when compiling
-Header files to include
-Choosing names
-Names for API (plugin)
-Names for methods
-Names for arguments
-Forging names widely available
-
-Writing a synchronous method implementation
-The incoming request
-Associating a client context to a session
-Sending reply to a request
-
-Getting argument of invocation
-Basic functions for querying arguments
-Arguments for received files
-Arguments as a JSON object
-
-Initialisation of the plugin and declaration of methods
-Sending messages to the log system
-Verbs for logging messages
-Managing verbosity
-Output format and destination
-
-Sending events
-Writing an asynchronous method implementation
-How to build a plugin
-Example for cmake meta build system
-Exporting the function pluginAfbV1Register
-Building within yocto
-
-
-
-
-HOWTO WRITE a PLUGIN for AFB-DAEMON
-version: 1
-Date:    09 juin 2016
-Author:  José Bollo
-Summary
-Afb-daemon binders serve files through HTTP protocol and offers to developers the capability to expose application API methods through HTTP or WebSocket protocol.
-Binder plugins are used to add API to afb-daemon. This part describes how to write a plugin for afb-daemon.
-Excepting this summary, this document target developers.
-Before moving further through an example, here after a short overview of binder plugins fundamentals.
-Nature of a plugin
-A plugin is an independent piece of software. A plugin is self contain and exposes application logic as sharable library. A plugin is intended to be dynamically loaded by afb-daemon to expose application API.
-Technically, a binder plugin does not reference and is not linked with any afb-daemon library.
-Class of plugins
-Application binder supports two kinds of plugins: application plugins and service plugins. Technically both class of plugin are equivalent are use the same coding convention. Only sharing mode and security context diverge.
-Application-plugins
-Application-plugins implements the glue in between application's UI and services. Every AGL application has a corresponding binder that typically activates one or many plugins to interface the application logic with lower platform services. When an application is started by the AGL application framework, a dedicate binder is started that loads/activates application plugin(s). API expose by application-plugin are executed within corresponding application security context.
-Application plugins generally handle a unique context for a unique client. As the application framework start a dedicated instance of afb_daemon for each AGL application, if a given plugin is used within multiple application each of those application get a new and private instance of eventually "shared" plugin.
-Service-plugins
-Service-plugins enable API activation within corresponding service security context and not within calling application context. Service-plugins are intended to run as a unique instance. Service-plugins can be shared in between multiple clients.
-Service-plugins can either be stateless or manage client context. When managing context each client get a private context.
-Sharing may either be global to the platform (ie: GPS service) or dedicated to a given user (ie: user preferences)
-Live cycle of plugins within afb-daemon
-Application and service plugins are loaded and activated each time a new afb-daemon is started.
-At launch time, every loaded plugin initialise itself. If a single plugin initialisation fail corresponding instance of afb-daemon self aborts.
-Conversely, when a plugin initialisation succeeds, it should register its unique name as well as the list of verbs attached to the methods it exposes.
-When initialised, on request from application clients to the right API/verb, plugin methods are activated by the afb-daemon attached to the application or service.
-At exit time, no special action is enforced by afb-daemon. When a specific actions is required at afb-daemon stop, developers should use 'atexit/on_exit' during plugin initialisation sequence to register a custom exit function.
-Plugin Contend
-Afb-daemon's plugin register two classes of objects: names and functions.
-Plugins declare categories of names: - A unique plugin name to access all API expose by this plugin, - One name for each methods/verbs provided by this plugin.
-Plugins declare two categories of functions: - function use for the initialisation - functions implementing exposed API methods
-Afb-daemon parses URI requests to extract the API(plugin name) and the VERB(method to activate). As an example, URI foo/bar translates to plugin named foo and method named bar. To serve such a request, afb-daemon looks for an active plugin named foo and then within this plugin for a method named bar. When find afb-daemon calls corresponding method with attached parameter if any.
-Afb-daemon ignores letter case when parsing URI. Thus TicTacToe/Board and tictactoe/board are equivalent.
-The name of the plugin
-The name of a given plugin is also known as the name of the API prefix that defines the plugin.
-The name of a plugin SHOULD be unique within a given afb-daemon instance.
-For example, when a client of afb-daemon calls a URI named foo/bar. Afb-daemon extracts the prefix foo and the suffix bar. foo must match a plugin name and bar a VERB attached to some method.
-Names of methods
-Each plugin exposes a set of methods that can be called by the clients of a given afb-daemon.
-VERB's name attached to a given plugin (API) MUST be unique within a plugin.
-Plugins static declaration link VERBS to corresponding methods. When clients emit requests on a given API/VERB corresponding method is called by afb-daemon.
-Initialisation function
-Plugin's initialisation function serves several purposes.
-
-It allows afb-daemon to control plugin version depending on initialisation function name. As today, the only supported initialisation function is pluginAfbV1Register. This identifies version "one" of plugins.
-It allows plugins to initialise itself.
-It enables names declarations: descriptions, requirements and implementations of exposed API/VERB.
-
-Functions instantiation of API/VERBs
-When an API/VERB is called, afb-daemon constructs a request object. Then it passes this request object to the implementation function corresponding to requested method, this within attached API plugin.
-An implementation function receives a request object that is used to: get arguments of the request, send answer, store session data.
-A plugin MUST set an answer to every received requests.
-Nevertheless it is not mandatory to set the answer before returning from API/VERB implementing function. This behaviour is important for asynchronous actions.
-API/VERB implementation that set an answer before returning are called synchronous implementations. Those that do not systematically set an answer before returning are called asynchronous implementations.
-Asynchronous implementations typically launch asynchronous actions. They record some context at request time and provide answer to the request only at completion of asynchronous actions.
-The Tic-Tac-Toe example
-This part explains how to write an afb-plugin. For the sake of being practical it uses many examples based on tic-tac-toe. This plugin example is in plugins/samples/tic-tac-toe.c.
-This plugin is named tictactoe.
-Dependencies when compiling
-Afb-daemon provides a configuration file for pkg-config. Typing the command
-pkg-config --cflags afb-daemon
-Print flags use for compilation:
-$ pkg-config --cflags afb-daemon
--I/opt/local/include -I/usr/include/json-c 
-For linking, you should use
-$ pkg-config --libs afb-daemon
--ljson-c
-Afb-daemon automatically includes dependency to json-c. This is activated through Requires keyword in pkg-config. While almost every plugin replies on json-c this is not a must have dependency.
-Internally, afb-daemon relies on libsystemd for its event loop, as well as for its binding to D-Bus. Plugins developers are encouraged to leverage libsystemd when possible. Nevertheless there is no hard dependency to libsystemd if ever you rather not use it, feel free to do so.
-
-Afb-daemon plugin are fully self contain. They do not enforce dependency on any libraries from the application framework. Afb-daemon dependencies requirer to run AGL plugins are given at runtime through pointers leveraging read-only memory feature.
-
-Header files to include
-Plugin tictactoe has following includes:
-#define _GNU_SOURCE
-#include <stdio.h>
-#include <string.h>
-#include <json-c/json.h>
-#include <afb/afb-plugin.h>
-Header afb/afb-plugin.h is the only hard dependency, it includes all features that a plugin MUST HAVE. Outside of includes used to support application logic, common external headers used within plugins are:
-
-json-c/json.h: should be include to handle json objects;
-systemd/sd-event.h: should be include to access event main loop;
-systemd/sd-bus.h: should be include for dbus connections.
-
-The tictactoe plugin does not leverage systemd features, also only json.h is used on top of mandatory afb/afb-plugin.h.
-When including afb/afb-plugin.h, the macro **_GNU_SOURCE** MUST be defined.
-Choosing names
-Designers of plugins should define a unique name for every API plugin as well as for methods VERBs. They should also define names for request arguments passed as name/value pair in URI.
-While forging names, designers should respect few rules to ensure that created names are valid and easy to use across platforms.
-All names and strings are UTF-8 encoded.
-Names for API (plugin)
-Plugin API name are checked. All characters are authorised except:
-
-the control characters (000 .. 01f)
-the characters of the set { ' ', '"', '#', '%', '&', ''', '/', '?', '`', '7f' }
-
-In other words the set of forbidden characters is { 000..020, 022, 023, 025..027, 02f, 03f, 060, 07f }.
-Afb-daemon makes no distinction between lower case and upper case when searching for API/VERB.
-Names for methods
-The names of methods VERBs are totally free and not checked.
-However, the validity rules for method's VERB name are the same as for Plugin API name except that the dot(.) character is forbidden.
-Afb-daemon makes no case distinction when searching for an API by name.
-Names for arguments
-Argument's name are not restricted and can be everything you wish.
-
-Warning arguments search is case sensitive and "index" and "Index" are not two different arguments.
-
-Forging names widely available
-The key names of javascript object can be almost anything using the arrayed notation:
-object[key] = value
-Nevertheless this is not the case with javascript dot notation:
-object.key = value
-Using the dot notation, the key must be a valid javascript identifier and dash(-) as well as few other reserved characters cannot be used.
-For this reason, we advise developper to chose name compatible with both javascript and HTML notation.
-It is a good practice, even for arguments not to rely on case sensitivity. This may reduce headache strength at debug time, especially with interpreted language like javascript that may not warn you that a variable was not defined.
-Writing a synchronous method implementation
-The method tictactoe/board is a synchronous implementation. Here is its listing:
-/*
- * get the board
- */
-static void board(struct afb_req req)
-{
-    struct board *board;
-    struct json_object *description;
-
-    /* retrieves the context for the session */
-    board = board_of_req(req);
-    INFO(afbitf, "method 'board' called for boardid %d", board->id);
-
-    /* describe the board */
-    description = describe(board);
-
-    /* send the board's description */
-    afb_req_success(req, description, NULL);
-}
-This example shows many aspects of a synchronous method implementation. Let summarise it:
-
-The function board_of_req retrieves the context stored for the plugin: the board.
-The macro INFO sends a message of kind INFO to the logging system. The global variable named afbitf used represents the interface to afb-daemon.
-The function describe creates a json_object representing the board.
-The function afb_req_success sends the reply, attaching to it the object description.
-
-The incoming request
-For any implementation, the request is received by a structure of type struct afb_req.
-
-Note that this is a PLAIN structure, not a pointer to a structure.
-
-The definition of struct afb_req is:
-/*
- * Describes the request by plugins from afb-daemon
- */
-struct afb_req {
-    const struct afb_req_itf *itf;  /* the interfacing functions */
-    void *closure;          /* the closure for functions */
-};
-It contains two pointers: first one itf, points to functions used to handle internal request. Second one closure point onto function closure.
-
-The structure must never be used directly. Instead developer should use the intended functions provided by afb-daemon as described here after.
-
-req is used to get arguments of the request, to send answer, to store session data.
-This object and its interface is defined and documented in the file names afb/afb-req-itf.h
-The above example uses twice req object request.
-The first time, to retrieve the board attached to the session of the request.
-The second time, to send the reply: an object that describes the current board.
-Associating a client context to a session
-When tic-tac-toe plugin receives a request, it musts get the board describing the game associated to the session.
-For a plugin, having data associated to a session is common. This data is called "plugin context" for the session. Within tic-tac-toe plugin the context is the board.
-Requests afb_req offer four functions for storing and retrieving session associated context.
-These functions are:
-
-afb_req_context_get: retrieves context data stored for current plugin.
-afb_req_context_set: store context data of current plugin.
-afb_req_context: if exist retrieves context data of current plugin. if context does not yet exist, creates a new context and store it.
-afb_req_context_clear: reset the stored context data.
-
-The plugin tictactoe use a convenient function to retrieve its context: the board. This function is board_of_req:
-/*
- * retrieves the board of the request
- */
-static inline struct board *board_of_req(struct afb_req req)
-{
-    return afb_req_context(req, (void*)get_new_board, (void*)release_board);
-}
-The function afb_req_context ensures an existing context for the session of the request. Its two last arguments are functions to allocate and free context. Note function type casts to avoid compilation warnings.
-Here is the definition of the function afb_req_context
-/*
- * Gets the pointer stored by the plugin for the session of 'req'.
- * If the stored pointer is NULL, indicating that no pointer was
- * already stored, afb_req_context creates a new context by calling
- * the function 'create_context' and stores it with the freeing function
- * 'free_context'.
- */
-static inline void *afb_req_context(struct afb_req req, void *(*create_context)(), void (*free_context)(void*))
-{
-    void *result = afb_req_context_get(req);
-    if (result == NULL) {
-        result = create_context();
-        afb_req_context_set(req, result, free_context);
-    }
-    return result;
-}
-The second argument if the function that creates the context. For plugin tic-tac-toe (function get_new_board). The function get_new_board creates a new board and set usage its count to 1. The boards are checking usage count to free resources when not used.
-The third argument is a function that frees context resources. For plugin tic-tac-toe (function release_board). The function release_board decrease usage count of the board passed in argument. When usage count falls to zero, data board are freed.
-Definition of other functions dealing with contexts:
-/*
- * Gets the pointer stored by the plugin for the session of 'req'.
- * When the plugin has not yet recorded a pointer, NULL is returned.
- */
-void *afb_req_context_get(struct afb_req req);
-
-/*
- * Stores for the plugin the pointer 'context' to the session of 'req'.
- * The function 'free_context' will be called when the session is closed
- * or if plugin stores an other pointer.
- */
-void afb_req_context_set(struct afb_req req, void *context, void (*free_context)(void*));
-
-/*
- * Frees the pointer stored by the plugin for the session of 'req'
- * and sets it to NULL.
- *
- * Shortcut for: afb_req_context_set(req, NULL, NULL)
- */
-static inline void afb_req_context_clear(struct afb_req req)
-{
-    afb_req_context_set(req, NULL, NULL);
-}
-Sending reply to a request
-Two kinds of replies: successful or failure.
-
-Sending a reply to a request MUST be done once and only once.
-
-It exists two functions for "success" replies: afb_req_success and afb_req_success_f.
-/*
- * Sends a reply of kind success to the request 'req'.
- * The status of the reply is automatically set to "success".
- * Its send the object 'obj' (can be NULL) with an
- * informationnal comment 'info (can also be NULL).
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_success(struct afb_req req, struct json_object *obj, const char *info);
-
-/*
- * Same as 'afb_req_success' but the 'info' is a formatting
- * string followed by arguments.
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...);
-It exists two functions for "failure" replies: afb_req_fail and afb_req_fail_f.
-/*
- * Sends a reply of kind failure to the request 'req'.
- * The status of the reply is set to 'status' and an
- * informational comment 'info' (can also be NULL) can be added.
- *
- * Note that calling afb_req_fail("success", info) is equivalent
- * to call afb_req_success(NULL, info). Thus even if possible it
- * is strongly recommended to NEVER use "success" for status.
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_fail(struct afb_req req, const char *status, const char *info);
-
-/*
- * Same as 'afb_req_fail' but the 'info' is a formatting
- * string followed by arguments.
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...);
-
-For conveniency, these functions automatically call json_object_put to release obj. Because obj usage count is null after being passed to a reply function, it SHOULD not be used anymore. If exceptionally obj needs to remain usable after reply function then using json_object_get on obj to increase usage count and cancels the effect the json_object_put is possible.
-
-Getting argument of invocation
-Many methods expect arguments. Afb-daemon's plugins retrieve arguments by name and not by position.
-Arguments are passed by requests through either HTTP or WebSockets.
-For example, the method join of plugin tic-tac-toe expects one argument: the boardid to join. Here is an extract:
-/*
- * Join a board
- */
-static void join(struct afb_req req)
-{
-    struct board *board, *new_board;
-    const char *id;
-
-    /* retrieves the context for the session */
-    board = board_of_req(req);
-    INFO(afbitf, "method 'join' called for boardid %d", board->id);
-
-    /* retrieves the argument */
-    id = afb_req_value(req, "boardid");
-    if (id == NULL)
-        goto bad_request;
-    ...
-The function afb_req_value searches in the request req for argument name passed in the second argument. When argument name is not passed, afb_req_value returns NULL.
-
-The search is case sensitive and boardid is not equivalent to BoardId. Nevertheless having argument names that only differ by name case is not a good idea.
-
-Basic functions for querying arguments
-The function afb_req_value is defined here after:
-/*
- * Gets from the request 'req' the string value of the argument of 'name'.
- * Returns NULL if when there is no argument of 'name'.
- * Returns the value of the argument of 'name' otherwise.
- *
- * Shortcut for: afb_req_get(req, name).value
- */
-static inline const char *afb_req_value(struct afb_req req, const char *name)
-{
-    return afb_req_get(req, name).value;
-}
-It is defined as a shortcut to call the function afb_req_get. That function is defined here after:
-/*
- * Gets from the request 'req' the argument of 'name'.
- * Returns a PLAIN structure of type 'struct afb_arg'.
- * When the argument of 'name' is not found, all fields of result are set to NULL.
- * When the argument of 'name' is found, the fields are filled,
- * in particular, the field 'result.name' is set to 'name'.
- *
- * There is a special name value: the empty string.
- * The argument of name "" is defined only if the request was made using
- * an HTTP POST of Content-Type "application/json". In that case, the
- * argument of name "" receives the value of the body of the HTTP request.
- */
-struct afb_arg afb_req_get(struct afb_req req, const char *name);
-That function takes 2 parameters: the request and the name of the argument to retrieve. It returns a PLAIN structure of type struct afb_arg.
-There is a special name that is defined when the request is of type HTTP/POST with a Content-Type being application/json. This name is "" (the empty string). In that case, the value of this argument of empty name is the string received as a body of the post and is supposed to be a JSON string.
-The definition of struct afb_arg is:
-/*
- * Describes an argument (or parameter) of a request
- */
-struct afb_arg {
-    const char *name;   /* name of the argument or NULL if invalid */
-    const char *value;  /* string representation of the value of the argument */
-                /* original filename of the argument if path != NULL */
-    const char *path;   /* if not NULL, path of the received file for the argument */
-                /* when the request is finalized this file is removed */
-};
-The structure returns the data arguments that are known for the request. This data include a field named path. This path can be accessed using the function afb_req_path defined here after:
-/*
- * Gets from the request 'req' the path for file attached to the argument of 'name'.
- * Returns NULL if when there is no argument of 'name' or when there is no file.
- * Returns the path of the argument of 'name' otherwise.
- *
- * Shortcut for: afb_req_get(req, name).path
- */
-static inline const char *afb_req_path(struct afb_req req, const char *name)
-{
-    return afb_req_get(req, name).path;
-}
-The path is only defined for HTTP/POST requests that send file.
-Arguments for received files
-As it is explained above, clients can send files using HTTP/POST requests.
-Received files are attached to "file" argument name. For example, the following HTTP fragment (from test/sample-post.html) will send an HTTP/POST request to the method post/upload-image with 2 arguments named file and hidden.
-<h2>Sample Post File</h2>
-<form enctype="multipart/form-data">
-    <input type="file" name="file" />
-    <input type="hidden" name="hidden" value="bollobollo" />
-    <br>
-    <button formmethod="POST" formaction="api/post/upload-image">Post File</button>
-</form>
-Argument named file should have both its value and path defined.
-The value is the name of the file as it was set by the HTTP client. Generally it is the filename on client side.
-The path is the effective path of saved file on the temporary local storage area of the application. This is a randomly generated and unique filename. It is not linked with the original filename as used on client side.
-After success the plugin can use the uploaded file directly from local storage path with no restriction: read, write, remove, copy, rename... Nevertheless when request reply is set and query terminated, the uploaded temporary file at path is destroyed.
-Arguments as a JSON object
-Plugins may also request every arguments of a given call as one single object. This feature is provided by the function afb_req_json defined here after:
-/*
- * Gets from the request 'req' the json object hashing the arguments.
- * The returned object must not be released using 'json_object_put'.
- */
-struct json_object *afb_req_json(struct afb_req req);
-It returns a json object. This object depends on how the request was built:
-
-For HTTP requests, this json object uses key names mapped on argument name. Values are either string for common arguments or object ie: { "file": "...", "path": "..." }
-For WebSockets requests, returned directly the object as provided by the client.
-
-
-In fact, for Websockets requests, the function afb_req_value can be seen as a shortcut to json_object_get_string(json_object_object_get(afb_req_json(req), name))
-
-Initialisation of the plugin and declaration of methods
-To be active, plugin's methods should be declared to afb-daemon. Furthermore, the plugin itself must be recorded.
-The registration mechanism is very basic: when afb-need starts, it loads all plugins listed in: command line or configuration file.
-Loading a plugin follows the following steps:
-
-Afb-daemon loads the plugin with dlopen.
-Afb-daemon searches for a symbol named pluginAfbV1Register using dlsym. This symbol is assumed to be the exported initialisation function of the plugin.
-Afb-daemon builds an interface object for the plugin.
-Afb-daemon calls the found function pluginAfbV1Register with interface pointer as parameter.
-Function pluginAfbV1Register setups the plugin and initialises it.
-Function pluginAfbV1Register returns the pointer to a structure describing the plugin: version, name (prefix or API name), and list of methods.
-Afb-daemon checks that the returned version and name can be managed. If so, plugin and its methods are register to become usable as soon as afb-daemon initialisation is finished.
-
-Here after the code used for pluginAfbV1Register from plugin tic-tac-toe:
-/*
- * activation function for registering the plugin called by afb-daemon
- */
-const struct AFB_plugin *pluginAfbV1Register(const struct AFB_interface *itf)
-{
-   afbitf = itf;         // records the interface for accessing afb-daemon
-   return &plugin_description;  // returns the description of the plugin
-}
-It is a very minimal initialisation function because tic-tac-toe plugin doesn't have any application related initialisation step. It merely record daemon's interface and returns its description.
-The variable afbitf is a plugin global variable. It keeps the interface to afb-daemon that should be used for logging and pushing events. Here is its declaration:
-/*
- * the interface to afb-daemon
- */
-const struct AFB_interface *afbitf;
-The description of the plugin is defined here after.
-/*
- * array of the methods exported to afb-daemon
- */
-static const struct AFB_method_desc_v1 plugin_methods[] = {
-   /* VERB'S NAME     SESSION MANAGEMENT          FUNCTION TO CALL  SHORT DESCRIPTION */
-   { .name= "new",   .session= AFB_SESSION_NONE, .callback= new,   .info= "Starts a new game" },
-   { .name= "play",  .session= AFB_SESSION_NONE, .callback= play,  .info= "Asks the server to play" },
-   { .name= "move",  .session= AFB_SESSION_NONE, .callback= move,  .info= "Tells the client move" },
-   { .name= "board", .session= AFB_SESSION_NONE, .callback= board, .info= "Get the current board" },
-   { .name= "level", .session= AFB_SESSION_NONE, .callback= level, .info= "Set the server level" },
-   { .name= "join",  .session= AFB_SESSION_CHECK,.callback= join,  .info= "Join a board" },
-   { .name= "undo",  .session= AFB_SESSION_NONE, .callback= undo,  .info= "Undo the last move" },
-   { .name= "wait",  .session= AFB_SESSION_NONE, .callback= wait,  .info= "Wait for a change" },
-   { .name= NULL } /* marker for end of the array */
-};
-
-/*
- * description of the plugin for afb-daemon
- */
-static const struct AFB_plugin plugin_description =
-{
-   /* description conforms to VERSION 1 */
-   .type= AFB_PLUGIN_VERSION_1,
-   .v1= {               /* fills the v1 field of the union when AFB_PLUGIN_VERSION_1 */
-      .prefix= "tictactoe",     /* the API name (or plugin name or prefix) */
-      .info= "Sample tac-tac-toe game", /* short description of of the plugin */
-      .methods = plugin_methods     /* the array describing the methods of the API */
-   }
-};
-The structure plugin_description describes the plugin. It declares the type and version of the plugin, its name, a short description and its methods list.
-The list of methods is an array of structures describing the methods and terminated by a NULL marker.
-In version one of afb-damon plugin, a method description contains 4 fields:
-
-the name of the method,
-the session management flags,
-the implementation function to be call for the method,
-a short description.
-
-The structure describing methods is defined as follows:
-/*
- * Description of one method of the API provided by the plugin
- * This enumeration is valid for plugins of type 1
- */
-struct AFB_method_desc_v1
-{
-       const char *name;                       /* name of the method */
-       enum AFB_session_v1 session;            /* authorisation and session requirements of the method */
-       void (*callback)(struct afb_req req);   /* callback function implementing the method */
-       const char *info;                       /* textual description of the method */
-};
-For technical reasons, the enumeration enum AFB_session_v1 is not exactly an enumeration but the wrapper of constant definitions that can be mixed using bitwise or (the C operator |).
-The constants that can bit mixed are:
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-Constant name Meaning
AFB_SESSION_CREATE Equals to AFB_SESSION_LOA_EQ_0
AFB_SESSION_CLOSE Closes the session after the reply and set the LOA to 0
AFB_SESSION_RENEW Refreshes the token of authentification
AFB_SESSION_CHECK Just requires the token authentification
AFB_SESSION_LOA_LE_0 Requires the current LOA to be lesser then or equal to 0
AFB_SESSION_LOA_LE_1 Requires the current LOA to be lesser then or equal to 1
AFB_SESSION_LOA_LE_2 Requires the current LOA to be lesser then or equal to 2
AFB_SESSION_LOA_LE_3 Requires the current LOA to be lesser then or equal to 3
AFB_SESSION_LOA_GE_0 Requires the current LOA to be greater then or equal to 0
AFB_SESSION_LOA_GE_1 Requires the current LOA to be greater then or equal to 1
AFB_SESSION_LOA_GE_2 Requires the current LOA to be greater then or equal to 2
AFB_SESSION_LOA_GE_3 Requires the current LOA to be greater then or equal to 3
AFB_SESSION_LOA_EQ_0 Requires the current LOA to be equal to 0
AFB_SESSION_LOA_EQ_1 Requires the current LOA to be equal to 1
AFB_SESSION_LOA_EQ_2 Requires the current LOA to be equal to 2
AFB_SESSION_LOA_EQ_3 Requires the current LOA to be equal to 3
-If any of this flag is set, afb-daemon requires an authentication token as if AFB_SESSION_CHECK flag was also set.
-The special value AFB_SESSION_NONE is zero and can be used to bypass token check.
-
-Note that AFB_SESSION_CREATE and AFB_SESSION_CLOSE might be removed in later versions.
-
-Sending messages to the log system
-Afb-daemon provides 4 levels of verbosity and 5 methods for logging messages.
-The verbosity is managed. Options allow the change the verbosity of afb-daemon and the verbosity of the plugins can be set plugin by plugin.
-The methods for logging messages are defined as macros that test the verbosity level and that call the real logging function only if the message must be output. This avoid evaluation of arguments of the formatting messages if the message must not be output.
-Verbs for logging messages
-The 5 logging methods are:
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-Macro Verbosity Meaning syslog level
ERROR 0 Error conditions 3
WARNING 1 Warning conditions 4
NOTICE 1 Normal but significant condition 5
INFO 2 Informational 6
DEBUG 3 Debug-level messages 7
-You can note that the 2 methods WARNING and INFO have the same level of verbosity. But they don't have the same syslog level. It means that they are output with a different level on the logging system.
-All of these methods have the same signature:
-void ERROR(const struct AFB_interface *afbitf, const char *message, ...);
-The first argument afbitf is the interface to afb daemon that the plugin received at initialisation time when pluginAfbV1Register is called.
-The second argument message is a formatting string compatible with printf/sprintf.
-The remaining arguments are arguments of the formating message like with printf.
-Managing verbosity
-Depending on the level of verbosity, the messages are output or not. The following table explains what messages will be output depending ont the verbosity level.
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-Level of verbosity Outputed macro
0 ERROR
1 ERROR + WARNING + NOTICE
2 ERROR + WARNING + NOTICE + INFO
3 ERROR + WARNING + NOTICE + INFO + DEBUG
-Output format and destination
-The syslog level is used for forging a prefix to the message. The prefixes are:
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-syslog level prefix
0 <0> EMERGENCY
1 <1> ALERT
2 <2> CRITICAL
3 <3> ERROR
4 <4> WARNING
5 <5> NOTICE
6 <6> INFO
7 <7> DEBUG
-The message is pushed to standard error. The final destination of the message depends on how systemd service was configured through its variable StandardError. It can be journal, syslog or kmsg. (See man sd-daemon).
-Sending events
-Since version 0.5, plugins can broadcast events to any potential listener. As today only unattended even are supported. Targeted events are expected for next coming version.
-The plugin tic-tac-toe broadcasts events when the board changes. This is done in the function changed:
-/*
- * signals a change of the board
- */
-static void changed(struct board *board, const char *reason)
-{
-    ...
-    struct json_object *description;
-
-    /* get the description */
-    description = describe(board);
-
-    ...
-
-    afb_daemon_broadcast_event(afbitf->daemon, reason, description);
-}
-The description of the changed board is pushed via the daemon interface.
-Within plugin tic-tac-toe, reason indicates the origin of the change. In function afb_daemon_broadcast_event the second parameter is the name of broadcasted event. The third argument is the object that is transmitted with the event.
-Function afb_daemon_broadcast_event is defined here after:
-/*
- * Broadcasts widely the event of 'name' with the data 'object'.
- * 'object' can be NULL.
- * 'daemon' MUST be the daemon given in interface when activating the plugin.
- *
- * For conveniency, the function calls 'json_object_put' for 'object'.
- * Thus, in the case where 'object' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_daemon_broadcast_event(struct afb_daemon daemon, const char *name, struct json_object *object);
-
-Be aware, as with reply functions object is automatically released using json_object_put when using this function. Call json_object_get before calling afb_daemon_broadcast_event to keep object available after function returns.
-
-Event name received by listeners is prefixed with plugin name. So when a change occurs after a move, the reason is move and every clients receive an event tictactoe/move.
-
-Note that nothing is said about case sensitivity of event names. However, the event is always prefixed with the name that the plugin declared, with the same case, followed with a slash /. Thus it is safe to compare event using a case sensitive comparison.
-
-Writing an asynchronous method implementation
-The tic-tac-toe example allows two clients or more to share the same board. This is implemented by the method join that illustrated partly how to retrieve arguments.
-When two or more clients are sharing a same board, one of them can wait until the state of the board changes, but this could also be implemented using events because an even is generated each time the board changes.
-In this case, the reply to the wait is sent only when the board changes. See the diagram below:
-CLIENT A       CLIENT B         TIC-TAC-TOE
-   |              |                  |
-   +--------------|----------------->| wait . . . . . . . .
-   |              |                  |                     .
-   :              :                  :                      .
-   :              :                  :                      .
-   |              |                  |                      .
-   |              +----------------->| move . . .           .
-   |              |                  |          V           .
-   |              |<-----------------+ success of move      .
-   |              |                  |                    .
-   |<-------------|------------------+ success of wait  <
-Here, this is an invocation of the plugin by an other client that unblock the suspended wait call. Nevertheless in most case this should be a timer, a hardware event, a sync with a concurrent process or thread, ...
-Common case of an asynchronous implementation.
-Here is the listing of the function wait:
-static void wait(struct afb_req req)
-{
-    struct board *board;
-    struct waiter *waiter;
-
-    /* retrieves the context for the session */
-    board = board_of_req(req);
-    INFO(afbitf, "method 'wait' called for boardid %d", board->id);
-
-    /* creates the waiter and enqueues it */
-    waiter = calloc(1, sizeof *waiter);
-    waiter->req = req;
-    waiter->next = board->waiters;
-    afb_req_addref(req);
-    board->waiters = waiter;
-}
-After retrieving the board, the function adds a new waiter to waiters list and returns without setting a reply.
-Before returning, it increases req request's reference count using afb_req_addref function.
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-When a method returns without setting a reply, it MUST increment request's reference count using afb_req_addref. If unpredictable behaviour may pop up.
-
-Later, when a board changes, it calls tic-tac-toe changed function with reason of change in parameter.
-Here is the full listing of the function changed:
-/*
- * signals a change of the board
- */
-static void changed(struct board *board, const char *reason)
-{
-    struct waiter *waiter, *next;
-    struct json_object *description;
-
-    /* get the description */
-    description = describe(board);
-
-    waiter = board->waiters;
-    board->waiters = NULL;
-    while (waiter != NULL) {
-        next = waiter->next;
-        afb_req_success(waiter->req, json_object_get(description), reason);
-        afb_req_unref(waiter->req);
-        free(waiter);
-        waiter = next;
-    }
-
-    afb_event_sender_push(afb_daemon_get_event_sender(afbitf->daemon), reason, description);
-}
-The list of waiters is walked and a reply is sent to each waiter. After sending the reply, the reference count of the request is decremented using afb_req_unref to allow resources to be freed.
-
-The reference count MUST be decremented using afb_req_unref to free resources and avoid memory leaks. This usage count decrement should happen AFTER setting reply or bad things may happen.
-
-How to build a plugin
-Afb-daemon provides a pkg-config configuration file that can be queried by providing afb-daemon in command line arguments. This configuration file provides data that should be used for plugins compilation. Examples:
-$ pkg-config --cflags afb-daemon
-$ pkg-config --libs afb-daemon
-Example for cmake meta build system
-This example is the extract for building the plugin afm-main using CMAKE.
-pkg_check_modules(afb afb-daemon)
-if(afb_FOUND)
-    message(STATUS "Creation afm-main-plugin for AFB-DAEMON")
-    add_library(afm-main-plugin MODULE afm-main-plugin.c)
-    target_compile_options(afm-main-plugin PRIVATE ${afb_CFLAGS})
-    target_include_directories(afm-main-plugin PRIVATE ${afb_INCLUDE_DIRS})
-    target_link_libraries(afm-main-plugin utils ${afb_LIBRARIES})
-    set_target_properties(afm-main-plugin PROPERTIES
-        PREFIX ""
-        LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-plugin.export-map"
-    )
-    install(TARGETS afm-main-plugin LIBRARY DESTINATION ${plugin_dir})
-else()
-    message(STATUS "Not creating the plugin for AFB-DAEMON")
-endif()
-Let now describe some of these lines.
-pkg_check_modules(afb afb-daemon)
-This first lines searches to the pkg-config configuration file for afb-daemon. Resulting data are stored in the following variables:
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Variable Meaning
afb_FOUND Set to 1 if afb-daemon plugin development files exist
afb_LIBRARIES Only the libraries (w/o the '-l') for compiling afb-daemon plugins
afb_LIBRARY_DIRS The paths of the libraries (w/o the '-L') for compiling afb-daemon plugins
afb_LDFLAGS All required linker flags for compiling afb-daemon plugins
afb_INCLUDE_DIRS The '-I' preprocessor flags (w/o the '-I') for compiling afb-daemon plugins
afb_CFLAGS All required cflags for compiling afb-daemon plugins
-If development files are found, the plugin can be added to the set of target to build.
-add_library(afm-main-plugin MODULE afm-main-plugin.c)
-This line asks to create a shared library having a single source file named afm-main-plugin.c to be compiled. The default name of the created shared object is libafm-main-plugin.so.
-set_target_properties(afm-main-plugin PROPERTIES
-    PREFIX ""
-    LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-plugin.export-map"
-)
-This lines are doing two things:
-
-It renames the built library from libafm-main-plugin.so to afm-main-plugin.so by removing the implicitly added prefix lib. This step is not mandatory because afb-daemon doesn't check names of files at load time. The only filename convention used by afb-daemon relates to .so termination. *.so pattern is used when afb-daemon automatically discovers plugin from a directory hierarchy.
-It applies a version script at link time to only export the reserved name pluginAfbV1Register for registration entry point. By default, when building a shared library linker exports all the public symbols (C functions that are not static).
-
-Next line are:
-target_include_directories(afm-main-plugin PRIVATE ${afb_INCLUDE_DIRS})
-target_link_libraries(afm-main-plugin utils ${afb_LIBRARIES})
-As you can see it uses the variables computed by pkg_check_modules(afb afb-daemon) to configure the compiler and the linker.
-Exporting the function pluginAfbV1Register
-The function pluginAfbV1Register MUST be exported. This can be achieved using a version script at link time. Here after is a version script used for tic-tac-toe (plugins/samples/export.map).
-{ global: pluginAfbV1Register; local: *; };
-This sample version script exports as global the symbol pluginAfbV1Register and hides any other symbols.
-This version script is added to the link options using the option --version-script=export.map is given directly to the linker or using the option -Wl,--version-script=export.map when the option is given to the C compiler.
-Building within yocto
-Adding a dependency to afb-daemon is enough. See below:
-DEPENDS += " afb-daemon "
-
-
diff --git a/doc/afb-plugin-writing.md b/doc/afb-plugin-writing.md
deleted file mode 100644
index 9e13d0d5..00000000
--- a/doc/afb-plugin-writing.md
+++ /dev/null
@@ -1,1227 +0,0 @@
-HOWTO WRITE a PLUGIN for AFB-DAEMON
-===================================
-    version: 1
-    Date:    09 juin 2016
-    Author:  José Bollo
-
-
-
-Summary
--------
-
-Afb-daemon binders serve files through HTTP protocol
-and offers to developers the capability to expose application API methods through
-HTTP or WebSocket protocol.
-
-Binder plugins are used to add API to afb-daemon.
-This part describes how to write a plugin for afb-daemon.
-
-Excepting this summary, this document target developers.
-
-Before moving further through an example, here after
-a short overview of binder plugins fundamentals.
-
-### Nature of a plugin
-
-A plugin is an independent piece of software. A plugin is self contain and exposes application logic as sharable library.
-A plugin is intended to be dynamically loaded by afb-daemon to expose application API.
-
-Technically, a binder plugin does not reference and is not linked with any afb-daemon library.
-
-### Class of plugins
-
-Application binder supports two kinds of plugins: application plugins and service plugins.
-Technically both class of plugin are equivalent are use the same coding convention. Only sharing mode and security context diverge.
-
-#### Application-plugins
-
-Application-plugins implements the glue in between application's UI and services. Every AGL application
-has a corresponding binder that typically activates one or many plugins to interface the application logic with lower platform services.
-When an application is started by the AGL application framework, a dedicate binder is started that loads/activates application plugin(s). 
-API expose by application-plugin are executed within corresponding application security context.
-
-Application plugins generally handle a unique context for a unique client. As the application framework start
-a dedicated instance of afb_daemon for each AGL application, if a given plugin is used within multiple application each of those
-application get a new and private instance of eventually "shared" plugin.
-
-#### Service-plugins
-
-Service-plugins enable API activation within corresponding service security context and not within calling application context. 
-Service-plugins are intended to run as a unique instance. Service-plugins can be shared in between multiple clients.
-
-Service-plugins can either be stateless or manage client context. When managing context each client get a private context.
-
-Sharing may either be global to the platform (ie: GPS service) or dedicated to a given user (ie: user preferences)
- 
-### Live cycle of plugins within afb-daemon
-
-Application and service plugins are loaded and activated each time a new afb-daemon is started.
-
-At launch time, every loaded plugin initialise itself.
-If a single plugin initialisation fail corresponding instance of afb-daemon self aborts.
-
-Conversely, when a plugin initialisation succeeds, it should register 
-its unique name as well as the list of verbs attached to the methods it exposes.
-
-When initialised, on request from application clients to the right API/verb, plugin methods
-are activated by the afb-daemon attached to the application or service.
-
-At exit time, no special action is enforced by afb-daemon. When a specific actions is required at afb-daemon stop,
-developers should use 'atexit/on_exit' during plugin initialisation sequence to register a custom exit function.
-
-### Plugin Contend
-
-Afb-daemon's plugin register two classes of objects: names and functions.
-
-Plugins declare categories of names:
- - A unique plugin name to access all API expose by this plugin,
- - One name for each methods/verbs provided by this plugin.
-
-Plugins declare two categories of functions:
- - function use for the initialisation
- - functions implementing exposed API methods
-
-Afb-daemon parses URI requests to extract the API(plugin name) and the VERB(method to activate).
-As an example, URI **foo/bar** translates to plugin named **foo** and method named **bar**.
-To serve such a request, afb-daemon looks for an active plugin named **foo** and then within this plugin for a method named **bar**.
-When find afb-daemon calls corresponding method with attached parameter if any.
-
-Afb-daemon ignores letter case when parsing URI. Thus **TicTacToe/Board** and **tictactoe/board** are equivalent.
-
-#### The name of the plugin
-
-The name of a given plugin is also known as the name
-of the API prefix that defines the plugin.
-
-The name of a plugin SHOULD be unique within a given afb-daemon instance.
-
-For example, when a client of afb-daemon calls a URI named **foo/bar**. Afb-daemon
-extracts the prefix **foo** and the suffix **bar**. **foo** must match a plugin name and **bar** a VERB attached to some method.
-
-#### Names of methods
-
-Each plugin exposes a set of methods that can be called
-by the clients of a given afb-daemon.
-
-VERB's name attached to a given plugin (API) MUST be unique within a plugin.
-
-Plugins static declaration link VERBS to corresponding methods. 
-When clients emit requests on a given API/VERB corresponding method is called by afb-daemon.
-
-#### Initialisation function
-
-Plugin's initialisation function serves several purposes.
-
-1. It allows afb-daemon to control plugin version depending on initialisation function name.
-As today, the only supported initialisation function is **pluginAfbV1Register**. This identifies
-version "one" of plugins.
-
-2. It allows plugins to initialise itself.
-
-3. It enables names declarations: descriptions, requirements and implementations of exposed API/VERB.
-
-#### Functions instantiation of API/VERBs
-
-When an API/VERB is called, afb-daemon constructs a request object. Then it 
-passes this request object to the implementation function corresponding to requested method, this
-within attached API plugin.
-
-An implementation function receives a request object that
-is used to: get arguments of the request, send
-answer, store session data.
-
-A plugin MUST set an answer to every received requests.
-
-Nevertheless it is not mandatory to set the answer
-before returning from API/VERB implementing function.
-This behaviour is important for asynchronous actions.
-
-API/VERB implementation that set an answer before returning are called *synchronous implementations*.
-Those that do not systematically set an answer before returning are called *asynchronous implementations*.
-
-Asynchronous implementations typically launch asynchronous actions. They record some context at
-request time and provide answer to the request only at completion of asynchronous actions.
-
-The Tic-Tac-Toe example
------------------------
-
-This part explains how to write an afb-plugin.
-For the sake of being practical it uses many
-examples based on tic-tac-toe.
-This plugin example is in *plugins/samples/tic-tac-toe.c*.
-
-This plugin is named ***tictactoe***.
-
-Dependencies when compiling
----------------------------
-
-Afb-daemon provides a configuration file for *pkg-config*.
-Typing the command
-
-	pkg-config --cflags afb-daemon
-
-Print flags use for compilation:
-
-	$ pkg-config --cflags afb-daemon
-	-I/opt/local/include -I/usr/include/json-c 
-
-For linking, you should use
-
-	$ pkg-config --libs afb-daemon
-	-ljson-c
-
-Afb-daemon automatically includes dependency to json-c.
-This is activated through **Requires** keyword in pkg-config.
-While almost every plugin replies on **json-c** this is not a must have dependency.
-
-Internally, afb-daemon relies on **libsystemd** for its event loop, as well 
-as for its binding to D-Bus.
-Plugins developers are encouraged to leverage **libsystemd** when possible.
-Nevertheless there is no hard dependency to **libsystemd** if ever
-you rather not use it, feel free to do so.
-
-> Afb-daemon plugin are fully self contain. They do not enforce dependency on any libraries from the application framework.
-> Afb-daemon dependencies requirer to run AGL plugins are given at runtime through pointers leveraging read-only
-> memory feature.
-
-Header files to include
------------------------
-
-Plugin *tictactoe* has following includes:
-
-```C
-#define _GNU_SOURCE
-#include 
-#include 
-#include 
-#include 
-```
-
-Header *afb/afb-plugin.h* is the only hard dependency, it includes all features
-that a plugin MUST HAVE. Outside of includes used to support application logic,
-common external headers used within plugins are:
-
-- *json-c/json.h*: should be include to handle json objects;
-- *systemd/sd-event.h*: should be include to access event main loop;
-- *systemd/sd-bus.h*: should be include for dbus connections.
-
-The *tictactoe* plugin does not leverage systemd features, also only json.h
-is used on top of mandatory afb/afb-plugin.h.
-
-When including *afb/afb-plugin.h*, the macro **_GNU_SOURCE** MUST be
-defined.
-
-Choosing names
---------------
-
-Designers of plugins should define a unique name for every API plugin
-as well as for methods VERBs. They should also define names for request
-arguments passed as name/value pair in URI.
-
-While forging names, designers should respect few rules to
-ensure that created names are valid and easy to use across platforms.
-
-All names and strings are UTF-8 encoded.
-
-### Names for API (plugin)
-
-Plugin API name are checked.
-All characters are authorised except:
-
-- the control characters (\u0000 .. \u001f)
-- the characters of the set { ' ', '"', '#', '%', '&',
-  '\'', '/', '?', '`', '\x7f' }
-
-In other words the set of forbidden characters is
-{ \u0000..\u0020, \u0022, \u0023, \u0025..\u0027,
-  \u002f, \u003f, \u0060, \u007f }.
-
-Afb-daemon makes no distinction between lower case
-and upper case when searching for API/VERB.
-
-### Names for methods
-
-The names of methods VERBs are totally free and not checked.
-
-However, the validity rules for method's VERB name are the
-same as for Plugin API name except that the dot(.) character
-is forbidden.
-
-Afb-daemon makes no case distinction when searching for an API by name.
-
-### Names for arguments
-
-Argument's name are not restricted and can be everything you wish.
-
-> Warning arguments search is case sensitive and "index" and "Index"
-> are not two different arguments.
-
-### Forging names widely available
-
-The key names of javascript object can be almost
-anything using the arrayed notation:
-
-	object[key] = value
-
-Nevertheless this is not the case with javascript dot notation:
-
-	object.key = value
-
-Using the dot notation, the key must be a valid javascript
-identifier and dash(-) as well as few other reserved characters cannot be used.
-
-For this reason, we advise developper to chose name compatible with both javascript and HTML notation.
-
-It is a good practice, even for arguments not to rely on case sensitivity.
-This may reduce headache strength at debug time, especially with interpreted language like
-javascript that may not warn you that a variable was not defined.
-
-Writing a synchronous method implementation
------------------------------------------
-
-The method **tictactoe/board** is a synchronous implementation.
-Here is its listing:
-
-```C
-/*
- * get the board
- */
-static void board(struct afb_req req)
-{
-	struct board *board;
-	struct json_object *description;
-
-	/* retrieves the context for the session */
-	board = board_of_req(req);
-	INFO(afbitf, "method 'board' called for boardid %d", board->id);
-
-	/* describe the board */
-	description = describe(board);
-
-	/* send the board's description */
-	afb_req_success(req, description, NULL);
-}
-```
-
-This example shows many aspects of a synchronous
-method implementation. Let summarise it:
-
-1. The function **board_of_req** retrieves the context stored
-for the plugin: the board.
-
-2. The macro **INFO** sends a message of kind *INFO*
-to the logging system. The global variable named **afbitf**
-used represents the interface to afb-daemon.
-
-3. The function **describe** creates a json_object representing
-the board.
-
-4. The function **afb_req_success** sends the reply, attaching to
-it the object *description*.
-
-### The incoming request
-
-For any implementation, the request is received by a structure of type
-**struct afb_req**.
-
-> Note that this is a PLAIN structure, not a pointer to a structure.
-
-The definition of **struct afb_req** is:
-
-```C
-/*
- * Describes the request by plugins from afb-daemon
- */
-struct afb_req {
-	const struct afb_req_itf *itf;	/* the interfacing functions */
-	void *closure;			/* the closure for functions */
-};
-```
-
-It contains two pointers: first one *itf*, points to functions used
-to handle internal request. Second one *closure* point onto function closure. 
-
-> The structure must never be used directly.
-> Instead developer should use the intended functions provided
-> by afb-daemon as described here after.
-
-*req* is used to get arguments of the request, to send
-answer, to store session data.
-
-This object and its interface is defined and documented
-in the file names *afb/afb-req-itf.h*
-
-The above example uses twice *req* object request.
-
-The first time, to retrieve the board attached to the session of the request.
-
-The second time, to send the reply: an object that describes the current board.
-
-### Associating a client context to a session
-
-When *tic-tac-toe* plugin receives a request, it musts get
-the board describing the game associated to the session.
-
-For a plugin, having data associated to a session is common.
-This data is called "plugin context" for the session.
-Within *tic-tac-toe* plugin the context is the board.
-
-Requests *afb_req* offer four functions for storing and retrieving session associated context.
-
-These functions are:
-
-- **afb_req_context_get**:
-  retrieves context data stored for current plugin.
-
-- **afb_req_context_set**:
-  store context data of current plugin.
-
-- **afb_req_context**:
-  if exist retrieves context data of current plugin.
-  if context does not yet exist, creates a new context and store it.
-
-- **afb_req_context_clear**:
-  reset the stored context data.
-
-The plugin *tictactoe* use a convenient function to retrieve
-its context: the board. This function is *board_of_req*:
-
-```C
-/*
- * retrieves the board of the request
- */
-static inline struct board *board_of_req(struct afb_req req)
-{
-	return afb_req_context(req, (void*)get_new_board, (void*)release_board);
-}
-```
-
-The function **afb_req_context** ensures an existing context
-for the session of the request.
-Its two last arguments are functions to allocate and free context. 
-Note function type casts to avoid compilation warnings.
-
-Here is the definition of the function **afb_req_context**
-
-```C
-/*
- * Gets the pointer stored by the plugin for the session of 'req'.
- * If the stored pointer is NULL, indicating that no pointer was
- * already stored, afb_req_context creates a new context by calling
- * the function 'create_context' and stores it with the freeing function
- * 'free_context'.
- */
-static inline void *afb_req_context(struct afb_req req, void *(*create_context)(), void (*free_context)(void*))
-{
-	void *result = afb_req_context_get(req);
-	if (result == NULL) {
-		result = create_context();
-		afb_req_context_set(req, result, free_context);
-	}
-	return result;
-}
-```
-
-The second argument if the function that creates the context.
-For plugin *tic-tac-toe* (function **get_new_board**).
-The function **get_new_board** creates a new board and set usage its count to 1.
-The boards are checking usage count to free resources when not used.
-
-The third argument is a function that frees context resources.
-For plugin *tic-tac-toe* (function **release_board**).
-The function **release_board** decrease usage count of the board passed in argument.
-When usage count falls to zero, data board are freed.
-
-Definition of other functions dealing with contexts:
-
-```C
-/*
- * Gets the pointer stored by the plugin for the session of 'req'.
- * When the plugin has not yet recorded a pointer, NULL is returned.
- */
-void *afb_req_context_get(struct afb_req req);
-
-/*
- * Stores for the plugin the pointer 'context' to the session of 'req'.
- * The function 'free_context' will be called when the session is closed
- * or if plugin stores an other pointer.
- */
-void afb_req_context_set(struct afb_req req, void *context, void (*free_context)(void*));
-
-/*
- * Frees the pointer stored by the plugin for the session of 'req'
- * and sets it to NULL.
- *
- * Shortcut for: afb_req_context_set(req, NULL, NULL)
- */
-static inline void afb_req_context_clear(struct afb_req req)
-{
-	afb_req_context_set(req, NULL, NULL);
-}
-```
-
-### Sending reply to a request
-
-Two kinds of replies: successful or failure.
-
-> Sending a reply to a request MUST be done once and only once.
-
-It exists two functions for "success" replies: **afb_req_success** and **afb_req_success_f**.
-
-```C
-/*
- * Sends a reply of kind success to the request 'req'.
- * The status of the reply is automatically set to "success".
- * Its send the object 'obj' (can be NULL) with an
- * informationnal comment 'info (can also be NULL).
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_success(struct afb_req req, struct json_object *obj, const char *info);
-
-/*
- * Same as 'afb_req_success' but the 'info' is a formatting
- * string followed by arguments.
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...);
-```
-
-It exists two functions for "failure" replies: **afb_req_fail** and **afb_req_fail_f**.
-
-```C
-/*
- * Sends a reply of kind failure to the request 'req'.
- * The status of the reply is set to 'status' and an
- * informational comment 'info' (can also be NULL) can be added.
- *
- * Note that calling afb_req_fail("success", info) is equivalent
- * to call afb_req_success(NULL, info). Thus even if possible it
- * is strongly recommended to NEVER use "success" for status.
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_fail(struct afb_req req, const char *status, const char *info);
-
-/*
- * Same as 'afb_req_fail' but the 'info' is a formatting
- * string followed by arguments.
- *
- * For conveniency, the function calls 'json_object_put' for 'obj'.
- * Thus, in the case where 'obj' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...);
-```
-
-> For conveniency, these functions automatically call **json_object_put** to release **obj**.
-> Because **obj** usage count is null after being passed to a reply function, it SHOULD not be used anymore.
-> If exceptionally **obj** needs to remain usable after reply function then using **json_object_get** on **obj**
-> to increase usage count and cancels the effect the **json_object_put** is possible.
-
-Getting argument of invocation
-------------------------------
-
-Many methods expect arguments. Afb-daemon's plugins
-retrieve arguments by name and not by position.
-
-Arguments are passed by requests through either HTTP
-or WebSockets.
-
-For example, the method **join** of plugin **tic-tac-toe**
-expects one argument: the *boardid* to join. Here is an extract:
-
-```C
-/*
- * Join a board
- */
-static void join(struct afb_req req)
-{
-	struct board *board, *new_board;
-	const char *id;
-
-	/* retrieves the context for the session */
-	board = board_of_req(req);
-	INFO(afbitf, "method 'join' called for boardid %d", board->id);
-
-	/* retrieves the argument */
-	id = afb_req_value(req, "boardid");
-	if (id == NULL)
-		goto bad_request;
-	...
-```
-
-The function **afb_req_value** searches in the request *req*
-for argument name passed in the second argument. When argument name
-is not passed, **afb_req_value** returns NULL.
-
-> The search is case sensitive and *boardid* is not equivalent to *BoardId*.
-> Nevertheless having argument names that only differ by name case is not a good idea.
-
-### Basic functions for querying arguments
-
-The function **afb_req_value** is defined here after:
-
-```C
-/*
- * Gets from the request 'req' the string value of the argument of 'name'.
- * Returns NULL if when there is no argument of 'name'.
- * Returns the value of the argument of 'name' otherwise.
- *
- * Shortcut for: afb_req_get(req, name).value
- */
-static inline const char *afb_req_value(struct afb_req req, const char *name)
-{
-	return afb_req_get(req, name).value;
-}
-```
-
-It is defined as a shortcut to call the function **afb_req_get**.
-That function is defined here after:
-
-```C
-/*
- * Gets from the request 'req' the argument of 'name'.
- * Returns a PLAIN structure of type 'struct afb_arg'.
- * When the argument of 'name' is not found, all fields of result are set to NULL.
- * When the argument of 'name' is found, the fields are filled,
- * in particular, the field 'result.name' is set to 'name'.
- *
- * There is a special name value: the empty string.
- * The argument of name "" is defined only if the request was made using
- * an HTTP POST of Content-Type "application/json". In that case, the
- * argument of name "" receives the value of the body of the HTTP request.
- */
-struct afb_arg afb_req_get(struct afb_req req, const char *name);
-```
-
-That function takes 2 parameters: the request and the name
-of the argument to retrieve. It returns a PLAIN structure of
-type **struct afb_arg**.
-
-There is a special name that is defined when the request is
-of type HTTP/POST with a Content-Type being application/json.
-This name is **""** (the empty string). In that case, the value
-of this argument of empty name is the string received as a body
-of the post and is supposed to be a JSON string.
-
-The definition of **struct afb_arg** is:
-
-```C
-/*
- * Describes an argument (or parameter) of a request
- */
-struct afb_arg {
-	const char *name;	/* name of the argument or NULL if invalid */
-	const char *value;	/* string representation of the value of the argument */
-				/* original filename of the argument if path != NULL */
-	const char *path;	/* if not NULL, path of the received file for the argument */
-				/* when the request is finalized this file is removed */
-};
-```
-
-The structure returns the data arguments that are known for the
-request. This data include a field named **path**. This **path**
-can be accessed using the function **afb_req_path** defined here after:
-
-```C
-/*
- * Gets from the request 'req' the path for file attached to the argument of 'name'.
- * Returns NULL if when there is no argument of 'name' or when there is no file.
- * Returns the path of the argument of 'name' otherwise.
- *
- * Shortcut for: afb_req_get(req, name).path
- */
-static inline const char *afb_req_path(struct afb_req req, const char *name)
-{
-	return afb_req_get(req, name).path;
-}
-```
-
-The path is only defined for HTTP/POST requests that send file.
-
-### Arguments for received files
-
-As it is explained above, clients can send files using HTTP/POST requests.
-
-Received files are attached to "file" argument name. For example, the
-following HTTP fragment (from test/sample-post.html)
-will send an HTTP/POST request to the method
-**post/upload-image** with 2 arguments named *file* and
-*hidden*.
-
-```html
-Sample Post File
-
-    
-    
-    

-    
-
-```
-
-Argument named **file** should have both its value and path defined.
-
-The value is the name of the file as it was set by the HTTP client.
-Generally it is the filename on client side.
-
-The path is the effective path of saved file on the temporary local storage
-area of the application. This is a randomly generated and unique filename. 
-It is not linked with the original filename as used on client side.
-
-After success the plugin can use the uploaded file directly from local storage path with no restriction:
-read, write, remove, copy, rename...
-Nevertheless when request reply is set and query terminated, the uploaded temporary file at
-path is destroyed.
-
-### Arguments as a JSON object
-
-Plugins may also request every arguments of a given call as one single object.
-This feature is provided by the function **afb_req_json** defined here after:
-
-```C
-/*
- * Gets from the request 'req' the json object hashing the arguments.
- * The returned object must not be released using 'json_object_put'.
- */
-struct json_object *afb_req_json(struct afb_req req);
-```
-
-It returns a json object. This object depends on how the request was built:
-
-- For HTTP requests, this json object uses key names mapped on argument name. 
-Values are either string for common arguments or object ie: { "file": "...", "path": "..." }
-
-- For WebSockets requests, returned directly the object as provided by the client.
-
-> In fact, for Websockets requests, the function **afb_req_value**
-> can be seen as a shortcut to
-> ***json_object_get_string(json_object_object_get(afb_req_json(req), name))***
-
-Initialisation of the plugin and declaration of methods
------------------------------------------------------
-
-To be active, plugin's methods should be declared to
-afb-daemon. Furthermore, the plugin itself must be recorded.
-
-The registration mechanism is very basic: when afb-need starts,
-it loads all plugins listed in: command line or configuration file.
-
-Loading a plugin follows the following steps:
-
-1. Afb-daemon loads the plugin with *dlopen*.
-
-2. Afb-daemon searches for a symbol named **pluginAfbV1Register** using *dlsym*.
-This symbol is assumed to be the exported initialisation function of the plugin.
-
-3. Afb-daemon builds an interface object for the plugin.
-
-4. Afb-daemon calls the found function **pluginAfbV1Register** with interface pointer
-as parameter.
-
-5. Function **pluginAfbV1Register** setups the plugin and initialises it.
-
-6. Function **pluginAfbV1Register** returns the pointer to a structure
-describing the plugin: version, name (prefix or API name), and list of methods.
-
-7. Afb-daemon checks that the returned version and name can be managed.
-If so, plugin and its methods are register to become usable as soon as
-afb-daemon initialisation is finished.
-
-Here after the code used for **pluginAfbV1Register** from plugin *tic-tac-toe*:
-
-```C
-/*
- * activation function for registering the plugin called by afb-daemon
- */
-const struct AFB_plugin *pluginAfbV1Register(const struct AFB_interface *itf)
-{
-   afbitf = itf;         // records the interface for accessing afb-daemon
-   return &plugin_description;  // returns the description of the plugin
-}
-```
-
-It is a very minimal initialisation function because *tic-tac-toe* plugin doesn't
-have any application related initialisation step. It merely record daemon's interface
-and returns its description.
-
-The variable **afbitf** is a plugin global variable. It keeps the
-interface to afb-daemon that should be used for logging and pushing events.
-Here is its declaration:
-
-```C
-/*
- * the interface to afb-daemon
- */
-const struct AFB_interface *afbitf;
-```
-
-The description of the plugin is defined here after.
-
-```C
-/*
- * array of the methods exported to afb-daemon
- */
-static const struct AFB_method_desc_v1 plugin_methods[] = {
-   /* VERB'S NAME     SESSION MANAGEMENT          FUNCTION TO CALL  SHORT DESCRIPTION */
-   { .name= "new",   .session= AFB_SESSION_NONE, .callback= new,   .info= "Starts a new game" },
-   { .name= "play",  .session= AFB_SESSION_NONE, .callback= play,  .info= "Asks the server to play" },
-   { .name= "move",  .session= AFB_SESSION_NONE, .callback= move,  .info= "Tells the client move" },
-   { .name= "board", .session= AFB_SESSION_NONE, .callback= board, .info= "Get the current board" },
-   { .name= "level", .session= AFB_SESSION_NONE, .callback= level, .info= "Set the server level" },
-   { .name= "join",  .session= AFB_SESSION_CHECK,.callback= join,  .info= "Join a board" },
-   { .name= "undo",  .session= AFB_SESSION_NONE, .callback= undo,  .info= "Undo the last move" },
-   { .name= "wait",  .session= AFB_SESSION_NONE, .callback= wait,  .info= "Wait for a change" },
-   { .name= NULL } /* marker for end of the array */
-};
-
-/*
- * description of the plugin for afb-daemon
- */
-static const struct AFB_plugin plugin_description =
-{
-   /* description conforms to VERSION 1 */
-   .type= AFB_PLUGIN_VERSION_1,
-   .v1= {				/* fills the v1 field of the union when AFB_PLUGIN_VERSION_1 */
-      .prefix= "tictactoe",		/* the API name (or plugin name or prefix) */
-      .info= "Sample tac-tac-toe game",	/* short description of of the plugin */
-      .methods = plugin_methods		/* the array describing the methods of the API */
-   }
-};
-```
-
-The structure **plugin_description** describes the plugin.
-It declares the type and version of the plugin, its name, a short description
-and its methods list.
-
-The list of methods is an array of structures describing the methods and terminated by a NULL marker.
-
-In version one of afb-damon plugin, a method description contains 4 fields:
-
-- the name of the method,
-
-- the session management flags,
-
-- the implementation function to be call for the method,
-
-- a short description.
-
-The structure describing methods is defined as follows:
-
-```C
-/*
- * Description of one method of the API provided by the plugin
- * This enumeration is valid for plugins of type 1
- */
-struct AFB_method_desc_v1
-{
-       const char *name;                       /* name of the method */
-       enum AFB_session_v1 session;            /* authorisation and session requirements of the method */
-       void (*callback)(struct afb_req req);   /* callback function implementing the method */
-       const char *info;                       /* textual description of the method */
-};
-```
-
-For technical reasons, the enumeration **enum AFB_session_v1** is not exactly an
-enumeration but the wrapper of constant definitions that can be mixed using bitwise or
-(the C operator |).
-
-The constants that can bit mixed are:
-
-Constant name            | Meaning
--------------------------|-------------------------------------------------------------
-**AFB_SESSION_CREATE**   | Equals to AFB_SESSION_LOA_EQ_0|AFB_SESSION_RENEW
-**AFB_SESSION_CLOSE**    | Closes the session after the reply and set the LOA to 0
-**AFB_SESSION_RENEW**    | Refreshes the token of authentification
-**AFB_SESSION_CHECK**    | Just requires the token authentification
-**AFB_SESSION_LOA_LE_0** | Requires the current LOA to be lesser then or equal to 0
-**AFB_SESSION_LOA_LE_1** | Requires the current LOA to be lesser then or equal to 1
-**AFB_SESSION_LOA_LE_2** | Requires the current LOA to be lesser then or equal to 2
-**AFB_SESSION_LOA_LE_3** | Requires the current LOA to be lesser then or equal to 3
-**AFB_SESSION_LOA_GE_0** | Requires the current LOA to be greater then or equal to 0
-**AFB_SESSION_LOA_GE_1** | Requires the current LOA to be greater then or equal to 1
-**AFB_SESSION_LOA_GE_2** | Requires the current LOA to be greater then or equal to 2
-**AFB_SESSION_LOA_GE_3** | Requires the current LOA to be greater then or equal to 3
-**AFB_SESSION_LOA_EQ_0** | Requires the current LOA to be equal to 0
-**AFB_SESSION_LOA_EQ_1** | Requires the current LOA to be equal to 1
-**AFB_SESSION_LOA_EQ_2** | Requires the current LOA to be equal to 2
-**AFB_SESSION_LOA_EQ_3** | Requires the current LOA to be equal to 3
-
-If any of this flag is set, afb-daemon requires an authentication token
-as if **AFB_SESSION_CHECK** flag was also set.
-
-The special value **AFB_SESSION_NONE** is zero and can be used to bypass token check.
-
-> Note that **AFB_SESSION_CREATE** and **AFB_SESSION_CLOSE** might be removed in later versions.
-
-Sending messages to the log system
-----------------------------------
-
-Afb-daemon provides 4 levels of verbosity and 5 methods for logging messages.
-
-The verbosity is managed. Options allow the change the verbosity of afb-daemon
-and the verbosity of the plugins can be set plugin by plugin.
-
-The methods for logging messages are defined as macros that test the
-verbosity level and that call the real logging function only if the
-message must be output. This avoid evaluation of arguments of the
-formatting messages if the message must not be output.
-
-### Verbs for logging messages
-
-The 5 logging methods are:
-
-Macro   | Verbosity | Meaning                           | syslog level
---------|:---------:|-----------------------------------|:-----------:
-ERROR   |     0     | Error conditions                  |     3
-WARNING |     1     | Warning conditions                |     4
-NOTICE  |     1     | Normal but significant condition  |     5
-INFO    |     2     | Informational                     |     6
-DEBUG   |     3     | Debug-level messages              |     7
-
-You can note that the 2 methods **WARNING** and **INFO** have the same level
-of verbosity. But they don't have the same *syslog level*. It means that
-they are output with a different level on the logging system.
-
-All of these methods have the same signature:
-
-```C
-void ERROR(const struct AFB_interface *afbitf, const char *message, ...);
-```
-
-The first argument **afbitf** is the interface to afb daemon that the
-plugin received at initialisation time when **pluginAfbV1Register** is called.
-
-The second argument **message** is a formatting string compatible with printf/sprintf.
-
-The remaining arguments are arguments of the formating message like with printf.
-
-### Managing verbosity
-
-Depending on the level of verbosity, the messages are output or not.
-The following table explains what messages will be output depending
-ont the verbosity level.
-
-Level of verbosity | Outputed macro
-:-----------------:|--------------------------
-0                  | ERROR
-1                  | ERROR + WARNING + NOTICE
-2                  | ERROR + WARNING + NOTICE + INFO
-3                  | ERROR + WARNING + NOTICE + INFO + DEBUG
-
-### Output format and destination
-
-The syslog level is used for forging a prefix to the message.
-The prefixes are:
-
-syslog level | prefix
-:-----------:|---------------
-0            | <0> EMERGENCY
-1            | <1> ALERT
-2            | <2> CRITICAL
-3            | <3> ERROR
-4            | <4> WARNING
-5            | <5> NOTICE
-6            | <6> INFO
-7            | <7> DEBUG
-
-
-The message is pushed to standard error.
-The final destination of the message depends on how systemd service
-was configured through its variable **StandardError**. It can be
-journal, syslog or kmsg. (See man sd-daemon).
-
-Sending events
---------------
-
-Since version 0.5, plugins can broadcast events to any potential listener.
-As today only unattended even are supported. Targeted events are expected for next
-coming version.
-
-The plugin *tic-tac-toe* broadcasts events when the board changes.
-This is done in the function **changed**:
-
-```C
-/*
- * signals a change of the board
- */
-static void changed(struct board *board, const char *reason)
-{
-	...
-	struct json_object *description;
-
-	/* get the description */
-	description = describe(board);
-
-	...
-
-	afb_daemon_broadcast_event(afbitf->daemon, reason, description);
-}
-```
-
-The description of the changed board is pushed via the daemon interface.
-
-Within plugin *tic-tac-toe*, *reason* indicates the origin of
-the change. In function **afb_daemon_broadcast_event** the second
-parameter is the name of broadcasted event. The third argument is the
-object that is transmitted with the event.
-
-Function **afb_daemon_broadcast_event** is defined here after:
-
-```C
-/*
- * Broadcasts widely the event of 'name' with the data 'object'.
- * 'object' can be NULL.
- * 'daemon' MUST be the daemon given in interface when activating the plugin.
- *
- * For conveniency, the function calls 'json_object_put' for 'object'.
- * Thus, in the case where 'object' should remain available after
- * the function returns, the function 'json_object_get' shall be used.
- */
-void afb_daemon_broadcast_event(struct afb_daemon daemon, const char *name, struct json_object *object);
-```
-
-> Be aware, as with reply functions **object** is automatically released using
-> **json_object_put** when using this function. Call **json_object_get** before
-> calling **afb_daemon_broadcast_event** to keep **object** available
-> after function returns.
-
-Event name received by listeners is prefixed with plugin name.
-So when a change occurs after a move, the reason is **move** and every clients
-receive an event **tictactoe/move**.
-
-> Note that nothing is said about case sensitivity of event names.
-> However, the event is always prefixed with the name that the plugin
-> declared, with the same case, followed with a slash /.
-> Thus it is safe to compare event using a case sensitive comparison.
-
-
-
-Writing an asynchronous method implementation
--------------------------------------------
-
-The *tic-tac-toe* example allows two clients or more to share the same board.
-This is implemented by the method **join** that illustrated partly how to
-retrieve arguments.
-
-When two or more clients are sharing a same board, one of them can wait
-until the state of the board changes, but this could also be implemented using
-events because an even is generated each time the board changes.
-
-In this case, the reply to the wait is sent only when the board changes.
-See the diagram below:
-
-	CLIENT A       CLIENT B         TIC-TAC-TOE
-	   |              |                  |
-	   +--------------|----------------->| wait . . . . . . . .
-	   |              |                  |                     .
-	   :              :                  :                      .
-	   :              :                  :                      .
-	   |              |                  |                      .
-	   |              +----------------->| move . . .           .
-	   |              |                  |          V           .
-	   |              |<-----------------+ success of move      .
-	   |              |                  |                    .
-	   |<-------------|------------------+ success of wait  <
-
-Here, this is an invocation of the plugin by an other client that
-unblock the suspended *wait* call.
-Nevertheless in most case this should be a timer, a hardware event, a sync with
-a concurrent process or thread, ...
-
-Common case of an asynchronous implementation.
-
-Here is the listing of the function **wait**:
-
-```C
-static void wait(struct afb_req req)
-{
-	struct board *board;
-	struct waiter *waiter;
-
-	/* retrieves the context for the session */
-	board = board_of_req(req);
-	INFO(afbitf, "method 'wait' called for boardid %d", board->id);
-
-	/* creates the waiter and enqueues it */
-	waiter = calloc(1, sizeof *waiter);
-	waiter->req = req;
-	waiter->next = board->waiters;
-	afb_req_addref(req);
-	board->waiters = waiter;
-}
-```
-
-After retrieving the board, the function adds a new waiter to
-waiters list and returns without setting a reply.
-
-Before returning, it increases **req** request's reference count using **afb_req_addref** function.
-
-> When a method returns without setting a reply,
-> it **MUST** increment request's reference count
-> using **afb_req_addref**. If unpredictable behaviour may pop up.
-
-Later, when a board changes, it calls *tic-tac-toe* **changed** function
-with reason of change in parameter.
-
-Here is the full listing of the function **changed**:
-
-```C
-/*
- * signals a change of the board
- */
-static void changed(struct board *board, const char *reason)
-{
-	struct waiter *waiter, *next;
-	struct json_object *description;
-
-	/* get the description */
-	description = describe(board);
-
-	waiter = board->waiters;
-	board->waiters = NULL;
-	while (waiter != NULL) {
-		next = waiter->next;
-		afb_req_success(waiter->req, json_object_get(description), reason);
-		afb_req_unref(waiter->req);
-		free(waiter);
-		waiter = next;
-	}
-
-	afb_event_sender_push(afb_daemon_get_event_sender(afbitf->daemon), reason, description);
-}
-```
-
-The list of waiters is walked and a reply is sent to each waiter.
-After sending the reply, the reference count of the request
-is decremented using **afb_req_unref** to allow resources to be freed.
-
-> The reference count **MUST** be decremented using **afb_req_unref** to free
-> resources and avoid memory leaks.
-> This usage count decrement should happen **AFTER** setting reply or 
-> bad things may happen.
-
-How to build a plugin
----------------------
-
-Afb-daemon provides a *pkg-config* configuration file that can be
-queried by providing **afb-daemon** in command line arguments.
-This configuration file provides data that should be used
-for plugins compilation. Examples:
-
-```bash
-$ pkg-config --cflags afb-daemon
-$ pkg-config --libs afb-daemon
-```
-
-### Example for cmake meta build system
-
-This example is the extract for building the plugin *afm-main* using *CMAKE*.
-
-```cmake
-pkg_check_modules(afb afb-daemon)
-if(afb_FOUND)
-	message(STATUS "Creation afm-main-plugin for AFB-DAEMON")
-	add_library(afm-main-plugin MODULE afm-main-plugin.c)
-	target_compile_options(afm-main-plugin PRIVATE ${afb_CFLAGS})
-	target_include_directories(afm-main-plugin PRIVATE ${afb_INCLUDE_DIRS})
-	target_link_libraries(afm-main-plugin utils ${afb_LIBRARIES})
-	set_target_properties(afm-main-plugin PROPERTIES
-		PREFIX ""
-		LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-plugin.export-map"
-	)
-	install(TARGETS afm-main-plugin LIBRARY DESTINATION ${plugin_dir})
-else()
-	message(STATUS "Not creating the plugin for AFB-DAEMON")
-endif()
-```
-
-Let now describe some of these lines.
-
-```cmake
-pkg_check_modules(afb afb-daemon)
-```
-
-This first lines searches to the *pkg-config* configuration file for
-**afb-daemon**. Resulting data are stored in the following variables:
-
-Variable          | Meaning
-------------------|------------------------------------------------
-afb_FOUND         | Set to 1 if afb-daemon plugin development files exist
-afb_LIBRARIES     | Only the libraries (w/o the '-l') for compiling afb-daemon plugins
-afb_LIBRARY_DIRS  | The paths of the libraries (w/o the '-L') for compiling afb-daemon plugins
-afb_LDFLAGS       | All required linker flags for compiling afb-daemon plugins
-afb_INCLUDE_DIRS  | The '-I' preprocessor flags (w/o the '-I') for compiling afb-daemon plugins
-afb_CFLAGS        | All required cflags for compiling afb-daemon plugins
-
-If development files are found, the plugin can be added to the set of
-target to build.
-
-```cmake
-add_library(afm-main-plugin MODULE afm-main-plugin.c)
-```
-
-This line asks to create a shared library having a single
-source file named afm-main-plugin.c to be compiled.
-The default name of the created shared object is
-**libafm-main-plugin.so**.
-
-```cmake
-set_target_properties(afm-main-plugin PROPERTIES
-	PREFIX ""
-	LINK_FLAGS "-Wl,--version-script=${CMAKE_CURRENT_SOURCE_DIR}/afm-main-plugin.export-map"
-)
-```
-
-This lines are doing two things:
-
-1. It renames the built library from **libafm-main-plugin.so** to **afm-main-plugin.so**
-by removing the implicitly added prefix *lib*. This step is not mandatory
-because afb-daemon doesn't check names of files at load time.
-The only filename convention used by afb-daemon relates to **.so** termination.
-*.so pattern is used when afb-daemon automatically discovers plugin from a directory hierarchy.
-
-2. It applies a version script at link time to only export the reserved name
-**pluginAfbV1Register** for registration entry point. By default, when building 
-a shared library linker exports all the public symbols (C functions that are not **static**).
-
-Next line are:
-
-```cmake
-target_include_directories(afm-main-plugin PRIVATE ${afb_INCLUDE_DIRS})
-target_link_libraries(afm-main-plugin utils ${afb_LIBRARIES})
-```
-
-As you can see it uses the variables computed by ***pkg_check_modules(afb afb-daemon)***
-to configure the compiler and the linker.
-
-### Exporting the function pluginAfbV1Register
-
-The function **pluginAfbV1Register** MUST be exported. This can be achieved
-using a version script at link time. Here after is a version script used for
-*tic-tac-toe* (plugins/samples/export.map).
-
-	{ global: pluginAfbV1Register; local: *; };
-
-This sample [version script](https://sourceware.org/binutils/docs-2.26/ld/VERSION.html#VERSION)
-exports as global the symbol *pluginAfbV1Register* and hides any
-other symbols.
-
-This version script is added to the link options using the
-option **--version-script=export.map** is given directly to the
-linker or using the option **-Wl,--version-script=export.map**
-when the option is given to the C compiler.
-
-### Building within yocto
-
-Adding a dependency to afb-daemon is enough. See below:
-
-	DEPENDS += " afb-daemon "
-
diff --git a/doc/afb-plugins-overview.html b/doc/afb-plugins-overview.html
deleted file mode 100644
index 291b7f79..00000000
--- a/doc/afb-plugins-overview.html
+++ /dev/null
@@ -1,159 +0,0 @@
-
-
-
-  
-  
-  
-  
-  
-  Overview of plugins shipped with AFB-Daemon
-  
-  
-  
-
-
-
-Overview of plugins shipped with AFB-Daemon
-Manuel Bachmann
-José Bollo
-09 juin 2016
-
-
-
-Overview of plugins shipped with AFB-Daemon
-List of plugins
-Detail of plugins
-Hello World
-Authentication
-Tic Tac Toe
-Audio
-Radio
-Media
-
-
-
-
-Overview of plugins shipped with AFB-Daemon
-Version: 1
-Date:    09 juin 2016
-Author:  Manuel Bachmann
-List of plugins
-Here are the plugins shipped in the source tree:
-
-Hello World
-Authentication
-Tic Tac Toe
-Audio (2 backends: ALSA/PulseAudio)
-Radio (1 backend: RTLSDR RTL2832U)
-Media (1 backend: Rygel UPnP)
-
-All plugins may not be built, depending on the development libraries present on the system at build time.
-Detail of plugins
-Hello World
-A sample Hello World plugin for demonstration and learning purposes.
-This plugin provides a few unauthenticated requests, all beginning with "ping", to demonstrate basic binder capabilities.
-Verbs:
-
-ping: returns a success response
-pingfail: returns a failure response
-pingnull: returns a success response, with an empty JSON response field
-pingbug: does a memory violation (intercepted by the binder)
-pingJson: returns a success response, with a complex JSON response field
-pingevent: broadcasts a global event
-
-

-Authentication
-An sample Authentication plugin for demonstration purposes.
-This plugin provides a few requests to demonstrate the binder's token-based security mechanism.
-Calling "connect" with a security token will initiate a session, calling "refresh" will issue a new token and invalidate the previous one, calling "logout" will invalidate all tokens and close the session.
-Verbs:
-
-ping: returns a success response
-connect: creates a session and returns a new token
-refresh: returns a new token
-check: verifies the passed token is valid
-logout: closes the session
-
-

-Tic Tac Toe
-A sample Tic Tac Toe game plugin.
-This plugin provides an interactive Tic Tac Toe game where the binder returns the grid as a JSON response.
-Verbs:
-
-new: starts a new game
-play: asks the server to play
-move: gives a client move
-board: gets the current board state, as a JSON structure
-level: sets the server level
-join: joins an existing board
-undo: undo the last move
-wait: wait for a move
-
-

-Audio
-A sample Audio plugin with 2 backends:
-
-ALSA (mandatory)
-PulseAudio (optional)
-
-This plugin is able to initialize a specific soundcard, define volume levels, channels (mono/stereo...), mute sound, and play a 22,050 Hz PCM stream.
-Verbs:
-
-ping: returns a success response
-init: initializes backend, on the "default" sound card
-volume: gets or sets volume, in % (0-100)
-channels: gets or sets channels count (1-8)
-mute: gets or sets the mute status (on-off)
-play: gets or sets the playing status (on-off)
-
-(if PulseAudio development libraries are not found at build time, only ALSA will be available)
-(if a PulseAudio server is not found at runtime, the plugin will dynamically fall back to ALSA)
-(a specifc backend can be forced by using this syntax before running afb-daemon : $ export AFB_AUDIO_OUTPUT=Alsa)
-

-Radio
-A sample AM/FM Radio plugin with 1 backend:
-
-RTLSDR - Realtek RTL2832U dongles (mandatory)
-
-This plugin is able to initialize specific RTL2832U dongles, switch between AM/FM modes, define frequency, mute sound, and play sound (if combining with the audio plugin).
-Verbs:
-
-ping: returns a success response
-init: initializes backend, looking for plugged-in devices
-power: sets device power status (on-off)
-mode: sets device reception mode (AM-FM)
-freq: sets device frequency (in Hz)
-mute: sets device mute status (on-off)
-play: sets device playing status (on-off)
-
-(if rtlsdr development libraries are not found at build time, this plugin will not be built)
-

-Media
-A sample Media Server plugin with 1 backend:
-
-Rygel
-
-This plugin is able to detect a local Rygel UPnP media server, list audio files, select an audio file for playback, play/pause/seek in this file, upload an audio file to the server.
-Verbs:
-
-ping: returns a success response
-init: initializes backend, looking for an active local UPnP server
-list: returns list of audio files, as a JSON structure
-select: select an audio files, by index number (001-...)
-play: plays the currently selected audio file
-stop: stops the currently selected audio file
-pause: pauses the currently selected audio file
-seek: seeks in the currently selected audio file, in seconds
-upload: uploads an audio file, with a POST request
-
-(if GUPnP/GSSDP development libraries are not fund at build time, this plugin will not be built)
-

-
-

-Sample command-line applications: afb-client-demo (built by default)
-Sample HTML5 applications: **test/*.html, afb-client, afb-radio**
-Sample Qt/QML applications: test/token-websock.qml
-
-
diff --git a/doc/afb-plugins-overview.md b/doc/afb-plugins-overview.md
deleted file mode 100644
index dfbe6010..00000000
--- a/doc/afb-plugins-overview.md
+++ /dev/null
@@ -1,168 +0,0 @@
-Overview of plugins shipped with AFB-Daemon
-===========================================
-    Version: 1
-    Date:    09 juin 2016
-    Author:  Manuel Bachmann
-
-
-List of plugins
----------------
-
-Here are the plugins shipped in the source tree:
-
-* Hello World
-* Authentication
-* Tic Tac Toe
-* Audio _(2 backends: ALSA/PulseAudio)_
-* Radio _(1 backend: RTLSDR RTL2832U)_
-* Media _(1 backend: Rygel UPnP)_
-
-All plugins may not be built, depending on the development libraries present on the system at build time.
-
-
-Detail of plugins
------------------
-
-### Hello World
-
-A sample Hello World plugin for demonstration and learning purposes.
-
-This plugin provides a few unauthenticated requests, all beginning with "ping", to demonstrate basic binder capabilities.
-
-**Verbs**:
-
-* _ping:_ returns a success response
-* _pingfail:_ returns a failure response
-* _pingnull:_ returns a success response, with an empty JSON response field
-* _pingbug:_ does a memory violation (intercepted by the binder)
-* _pingJson:_ returns a success response, with a complex JSON response field
-* _pingevent:_ broadcasts a global event
-
-

-
-
-### Authentication
-
-An sample Authentication plugin for demonstration purposes.
-
-This plugin provides a few requests to demonstrate the binder's token-based security mechanism.
-
-Calling "_connect_" with a security token will initiate a session, calling "_refresh_" will issue a new token and invalidate the previous one, calling "_logout_" will invalidate all tokens and close the session.
-
-**Verbs**:
-
-* _ping:_ returns a success response
-* _connect:_ creates a session and returns a new token
-* _refresh:_ returns a new token
-* _check:_ verifies the passed token is valid
-* _logout:_ closes the session
-
-

-
-
-### Tic Tac Toe
-
-A sample Tic Tac Toe game plugin.
-
-This plugin provides an interactive Tic Tac Toe game where the binder returns the grid as a JSON response. 
-
-**Verbs**:
-
-* _new:_ starts a new game
-* _play:_ asks the server to play
-* _move:_ gives a client move
-* _board:_ gets the current board state, as a JSON structure
-* _level_: sets the server level
-* _join_: joins an existing board
-* _undo_: undo the last move
-* _wait_: wait for a move
-
-

-
-
-### Audio
-
-A sample Audio plugin with 2 backends:
-
-* ALSA (mandatory)
-* PulseAudio (optional)
-
-This plugin is able to initialize a specific soundcard, define volume levels, channels (mono/stereo...), mute sound, and play a 22,050 Hz PCM stream.
-
-**Verbs**:
-
-* _ping:_ returns a success response
-* _init:_ initializes backend, on the "default" sound card
-* _volume:_ gets or sets volume, in % (0-100)
-* _channels:_ gets or sets channels count (1-8)
-* _mute:_ gets or sets the mute status (on-off)
-* _play_: gets or sets the playing status (on-off)
-
-_(if PulseAudio development libraries are not found at build time, only ALSA will be available)_
-
-_(if a PulseAudio server is not found at runtime, the plugin will dynamically fall back to ALSA)_
-
-_(a specifc backend can be forced by using this syntax before running afb-daemon : **$ export AFB_AUDIO_OUTPUT=Alsa**)_
-
-

-
-
-### Radio
-
-A sample AM/FM Radio plugin with 1 backend:
-
-* RTLSDR - Realtek RTL2832U dongles (mandatory)
-
-This plugin is able to initialize specific RTL2832U dongles, switch between AM/FM modes, define frequency, mute sound, and play sound (if combining with the **audio** plugin).
-
-**Verbs**:
-
-* _ping:_ returns a success response
-* _init:_ initializes backend, looking for plugged-in devices
-* _power:_ sets device power status (on-off)
-* _mode:_ sets device reception mode (AM-FM)
-* _freq:_ sets device frequency (in Hz)
-* _mute_: sets device mute status (on-off)
-* _play_: sets device playing status (on-off)
-
-_(if rtlsdr development libraries are not found at build time, this plugin will not be built)_
-
-

-
-
-### Media
-
-A sample Media Server plugin with 1 backend:
-
- * Rygel
-
-This plugin is able to detect a local Rygel UPnP media server, list audio files, select an audio file for playback, play/pause/seek in this file, upload an audio file to the server.
-
-**Verbs**:
-
-* _ping:_ returns a success response
-* _init:_ initializes backend, looking for an active local UPnP server
-* _list:_ returns list of audio files, as a JSON structure
-* _select:_ select an audio files, by index number (001-...)
-* _play:_ plays the currently selected audio file
-* _stop:_ stops the currently selected audio file
-* _pause:_ pauses the currently selected audio file
-* _seek:_ seeks in the currently selected audio file, in seconds
-* _upload:_ uploads an audio file, with a POST request
-
-_(if GUPnP/GSSDP development libraries are not fund at build time, this plugin will not be built)_
-
-

-
-
----
-

-
-Sample command-line applications: _afb-client-demo_ (built by default)
-
-Sample HTML5 applications: 
-**test/*.html**, 
-**[afb-client](https://gerrit.automotivelinux.org/gerrit/gitweb?p=src/app-framework-demo.git;a=tree)**, 
-**[afb-radio](https://github.com/iotbzh/afb-radio)**
-
-Sample Qt/QML applications: *test/token-websock.qml*
diff --git a/doc/afb-tests-overview.html b/doc/afb-tests-overview.html
index e9711c4e..b29c1920 100644
--- a/doc/afb-tests-overview.html
+++ b/doc/afb-tests-overview.html
@@ -18,7 +18,7 @@
 Overview of tests shipped with AFB-Daemon
 Manuel Bachmann
 José Bollo
-09 juin 2016
+23 juin 2016
 
 
 
@@ -45,12 +45,12 @@ Author:  Manuel Bachmann

Detail of tests

afb-client-demo (command-line WebSockets)

This clients interactively calls plugins APIs from the command line, using the binder WebSockets facility.

This clients interactively calls bindings APIs from the command line, using the binder WebSockets facility.

If afb-daemon has been launched with the following parameters:

$ afb-daemon --port=1234 --token=123456 [...]

Then run the client with :

afb-client-demo ws://localhost:1234/api?token=123456 [<api> <verb> [<json-data>]]

For instance, to initialize the Audio plugin from the command line :

For instance, to initialize the Audio binding from the command line :

afb-client-demo ws://localhost:1234/api?token=123456

The command doesn't return. You should type requests of type []. So, try:

auth connect
diff --git a/doc/afb-tests-overview.md b/doc/afb-tests-overview.md
index 6bb1b8a9..4fc0c9b2 100644
--- a/doc/afb-tests-overview.md
+++ b/doc/afb-tests-overview.md
@@ -22,7 +22,7 @@ Detail of tests
 
 ### afb-client-demo (command-line WebSockets)
 
-This clients interactively calls plugins APIs from the command line, using the binder
+This clients interactively calls bindings APIs from the command line, using the binder
 [WebSockets](https://en.wikipedia.org/wiki/WebSocket) facility.
 
 If _afb-daemon_ has been launched with the following parameters:
@@ -35,7 +35,7 @@ Then run the client with :
 
     afb-client-demo ws://localhost:1234/api?token=123456 [  []]
 
-For instance, to initialize the Audio plugin from the command line :
+For instance, to initialize the Audio binding from the command line :
 
     afb-client-demo ws://localhost:1234/api?token=123456
 
-- 
cgit 1.2.3-korg