From d96d0533b8326570db57d13b8f808bc62d1a7fa4 Mon Sep 17 00:00:00 2001 From: José Bollo Date: Fri, 27 May 2016 22:18:26 +0200 Subject: improves documentation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Change-Id: Idbd1b735571c2e35daed23d43f8d5d3990881533 Signed-off-by: José Bollo --- doc/FAQ.html | 2 +- doc/FAQ.md | 2 +- doc/afb-daemon-vocabulary.html | 2 +- doc/afb-daemon-vocabulary.md | 2 +- doc/afb-plugin-writing.html | 202 +++++++++++++++++++++++++++++------------ doc/afb-plugin-writing.md | 179 ++++++++++++++++++++++++++---------- 6 files changed, 280 insertions(+), 109 deletions(-) (limited to 'doc') diff --git a/doc/FAQ.html b/doc/FAQ.html index ffda81af..98337815 100644 --- a/doc/FAQ.html +++ b/doc/FAQ.html @@ -8,7 +8,7 @@

Frequently Asked Question about AFB-DAEMON

version: 1
-Date:    26 mai 2016
+Date:    27 mai 2016
 Author:  José Bollo
diff --git a/doc/FAQ.md b/doc/FAQ.md index 93647311..61105823 100644 --- a/doc/FAQ.md +++ b/doc/FAQ.md @@ -1,7 +1,7 @@ Frequently Asked Question about AFB-DAEMON ========================================== version: 1 - Date: 26 mai 2016 + Date: 27 mai 2016 Author: José Bollo TABLE-OF-CONTENT-HERE diff --git a/doc/afb-daemon-vocabulary.html b/doc/afb-daemon-vocabulary.html index 096f5076..fadd1dee 100644 --- a/doc/afb-daemon-vocabulary.html +++ b/doc/afb-daemon-vocabulary.html @@ -8,7 +8,7 @@

Vocabulary for AFB-DAEMON

version: 1
-Date:    26 mai 2016
+Date:    27 mai 2016
 Author:  José Bollo
diff --git a/doc/afb-daemon-vocabulary.md b/doc/afb-daemon-vocabulary.md index 71771947..8427b736 100644 --- a/doc/afb-daemon-vocabulary.md +++ b/doc/afb-daemon-vocabulary.md @@ -1,7 +1,7 @@ Vocabulary for AFB-DAEMON ========================= version: 1 - Date: 26 mai 2016 + Date: 27 mai 2016 Author: José Bollo TABLE-OF-CONTENT-HERE diff --git a/doc/afb-plugin-writing.html b/doc/afb-plugin-writing.html index 9a98ffe9..9873b626 100644 --- a/doc/afb-plugin-writing.html +++ b/doc/afb-plugin-writing.html @@ -37,6 +37,8 @@ Author: José Bollo
  • The Tic-Tac-Toe example
    • +
  • Dependencies when compiling
    • +
  • Header files to include
  • Choosing names
    • -
  • Options to set when compiling plugins
    • -
  • Header files to include
  • Writing a synchronous verb implementation
    • The incoming request
      • @@ -265,6 +265,72 @@ 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
+
      + +

      will print the flags to use for compiling, like this:

      + +
      $ 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
+
      + +

      As you see, afb-daemon automatically includes dependency to json-c. +This is done through the Requires keyword of pkg-config +because almost all plugin will use json-c.

      + +

      If this behaviour is a problem, let us know.

      + +

      Internally, afb-daemon uses libsystemd for its event loop +and for its binding to D-Bus. +Plugins developpers are encouraged to also use this library. +But it is a matter of choice. +Thus there is no dependency to libsystemd.

      + +

      Afb-daemon provides no library for plugins. +The functions that the plugin need to have are given +to the plugin at runtime through pointer using read-only +memory.

      + + +

      Header files to include

      + +

      The plugin tictactoe has the following lines for its includes:

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

      The header afb/afb-plugin.h includes all the features that a plugin +needs except two foreign header that must be included by the plugin +if it needs it:

      + +
        +
      • json-c/json.h: this header must be include to handle json objects;
        • +
      • systemd/sd-event.h: this must be include to access the main loop;
        • +
      • systemd/sd-bus.h: this may be include to use dbus connections.
        • +
      + + +

      The tictactoe plugin does not use systemd features so it is not included.

      + +

      When including afb/afb-plugin.h, the macro _GNU_SOURCE must be +defined.

      +

      Choosing names

      @@ -344,60 +410,6 @@ valid javascript identifier.

      rely on the case sensitivity and to avoid the use of names different only by the case.

      - -

      Options to set when compiling plugins

      - -

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

      - -
      pkg-config --cflags afb-daemon
-
      - -

      will print the flags to use for compiling, like this:

      - -
      $ 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
-
      - -

      As you see, afb-daemon automatically includes dependency to json-c. -This is done through the Requires keyword of pkg-config.

      - -

      If this behaviour is a problem, let us know.

      - - -

      Header files to include

      - -

      The plugin tictactoe has the following lines for its includes:

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

      The header afb/afb-plugin.h includes all the features that a plugin -needs except two foreign header that must be included by the plugin -if it needs it:

      - -
        -
      • json-c/json.h: this header must be include to handle json objects;
        • -
      • systemd/sd-event.h: this must be include to access the main loop;
        • -
      • systemd/sd-bus.h: this may be include to use dbus connections.
        • -
      - - -

      The tictactoe plugin does not use systemd features so it is not included.

      - -

      When including afb/afb-plugin.h, the macro _GNU_SOURCE must be -defined.

      -

      Writing a synchronous verb implementation

      @@ -879,7 +891,7 @@ const struct AFB_interface *afbitf; static const struct AFB_verb_desc_v1 plugin_verbs[] = { /* 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= "Tells the server to play" }, + { .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" }, @@ -1196,9 +1208,85 @@ journal, syslog or kmsg. (See man sd-daemon).

      Sending events

      +

      Since version 0.5, plugins can broadcast events to any potential listener. +This kind of bradcast is not targeted. Event targeted will come in a future +version of afb-daemon.

      + +

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

      + +

      The function afb_daemon_broadcast_event is defined as below:

      + +
      /*
+ * 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.
+ */
+void afb_daemon_broadcast_event(struct afb_daemon daemon, const char *name, struct json_object *object);
+
      + +

      In fact the event name received by the listener is prefixed with +the name of the plugin. So when the change occurs after a move, the +reason is move and then the clients receive the event tictactoe/move.

      + +

      Note that nothing is said about the 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 verb implementation

      +

      / + * 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);
+
      + +

      }

      +

      How to build a plugin

      diff --git a/doc/afb-plugin-writing.md b/doc/afb-plugin-writing.md index 734b15a5..7861021b 100644 --- a/doc/afb-plugin-writing.md +++ b/doc/afb-plugin-writing.md @@ -178,6 +178,65 @@ 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 + +will print the flags to use for compiling, like this: + + $ 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 + +As you see, afb-daemon automatically includes dependency to json-c. +This is done through the **Requires** keyword of pkg-config +because almost all plugin will use **json-c**. + +If this behaviour is a problem, let us know. + +Internally, afb-daemon uses **libsystemd** for its event loop +and for its binding to D-Bus. +Plugins developpers are encouraged to also use this library. +But it is a matter of choice. +Thus there is no dependency to **libsystemd**. + +> Afb-daemon provides no library for plugins. +> The functions that the plugin need to have are given +> to the plugin at runtime through pointer using read-only +> memory. + +Header files to include +----------------------- + +The plugin *tictactoe* has the following lines for its includes: + + #define _GNU_SOURCE + #include + #include + #include + #include + +The header *afb/afb-plugin.h* includes all the features that a plugin +needs except two foreign header that must be included by the plugin +if it needs it: + +- *json-c/json.h*: this header must be include to handle json objects; +- *systemd/sd-event.h*: this must be include to access the main loop; +- *systemd/sd-bus.h*: this may be include to use dbus connections. + +The *tictactoe* plugin does not use systemd features so it is not included. + +When including *afb/afb-plugin.h*, the macro **_GNU_SOURCE** must be +defined. + Choosing names -------------- @@ -248,53 +307,6 @@ It is also a good practice, even for arguments, to not rely on the case sensitivity and to avoid the use of names different only by the case. -Options to set when compiling plugins -------------------------------------- - -Afb-daemon provides a configuration file for *pkg-config*. -Typing the command - - pkg-config --cflags afb-daemon - -will print the flags to use for compiling, like this: - - $ 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 - -As you see, afb-daemon automatically includes dependency to json-c. -This is done through the **Requires** keyword of pkg-config. - -If this behaviour is a problem, let us know. - -Header files to include ------------------------ - -The plugin *tictactoe* has the following lines for its includes: - - #define _GNU_SOURCE - #include - #include - #include - #include - -The header *afb/afb-plugin.h* includes all the features that a plugin -needs except two foreign header that must be included by the plugin -if it needs it: - -- *json-c/json.h*: this header must be include to handle json objects; -- *systemd/sd-event.h*: this must be include to access the main loop; -- *systemd/sd-bus.h*: this may be include to use dbus connections. - -The *tictactoe* plugin does not use systemd features so it is not included. - -When including *afb/afb-plugin.h*, the macro **_GNU_SOURCE** must be -defined. - Writing a synchronous verb implementation ----------------------------------------- @@ -755,7 +767,7 @@ The description of the plugin is defined as below. static const struct AFB_verb_desc_v1 plugin_verbs[] = { /* 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= "Tells the server to play" }, + { .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" }, @@ -920,10 +932,81 @@ journal, syslog or kmsg. (See man sd-daemon). Sending events -------------- +Since version 0.5, plugins can broadcast events to any potential listener. +This kind of bradcast is not targeted. Event targeted will come in a future +version of afb-daemon. + +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 the plugin *tic-tac-toe*, the *reason* indicates the origin of +the change. For the function **afb_daemon_broadcast_event**, the second +parameter is the name of the broadcasted event. The third argument is the +object that is transmitted with the event. + +The function **afb_daemon_broadcast_event** is defined as below: + + /* + * 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. + */ + void afb_daemon_broadcast_event(struct afb_daemon daemon, const char *name, struct json_object *object); + +In fact the event name received by the listener is prefixed with +the name of the plugin. So when the change occurs after a move, the +reason is **move** and then the clients receive the event **tictactoe/move**. + +> Note that nothing is said about the 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 verb implementation ------------------------------------------- +/* + * 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); +} How to build a plugin --------------------- -- cgit