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+The application framework daemons
+=================================
+
+Foreword
+--------
+
+This document describes application framework daemons
+FCF (Fully Conform to Specification) implementation is still under development.
+It may happen that current implementation somehow diverges with specifications.
+
+Introduction
+------------
+
+Daemons ***afm-user-daemon*** and ***afm-system-daemon*** handle applications
+life. Understand that they will manage operations like:
+
+ - ***installation***
+ - ***uninstallation***
+ - ***running***
+ - ***suspend***
+ - ***inventory***
+ - ...
+
+In addition, they ensure that operations use the security framework as needed
+and that applications are executed in the correct context.
+
+***D-Bus*** is in charge of transmitting orders to the appropriate daemon
+depending upon ***D-Bus*** destination.
+
+The figure below summarizes the situation of both **afm-system-daemon** and
+**afm-user-daemon** in the system.
+
+![afm-daemons][afm-daemons]
+
+The D-Bus interface
+-------------------
+
+### Overview of the dbus interface
+
+The ***afm daemons*** takes theirs orders from the session instance
+of D-Bus. The use of D-Bus is great because it allows to implement
+discovery and signaling.
+
+The dbus session is by default addressed by environment
+variable *DBUS_SESSION_BUS_ADDRESS*. Using **systemd**
+variable *DBUS_SESSION_BUS_ADDRESS* is automatically set for
+user sessions.
+
+They are listening with the destination name ***org.AGL.afm.[user|system]***
+at the object of path ***/org/AGL/afm/[user|system]*** on the interface
+***org.AGL.afm.[user|system]***  for the below detailed members for the
+***afm-system-daemon***:
+
+ - ***install***
+ - ***uninstall***
+
+And for ***afm-user-daemon***:
+
+ - ***runnables***
+ - ***detail***
+ - ***start***
+ - ***once***
+ - ***terminate***
+ - ***pause***
+ - ***resume***
+ - ***runners***
+ - ***state***
+ - ***install***
+ - ***uninstall***
+
+D-Bus is mainly used for signaling and discovery. Its optimized
+typed protocol is not used except for transmitting only one string
+in both directions.
+
+The client and the service are using JSON serialization to
+exchange data. Signature of any member of the D-Bus interface is
+***string -> string*** for ***JSON -> JSON***. This is the normal case, if there
+is an error, current implementation returns a dbus error that is a string.
+
+Here are examples using *dbus-send*, here to install an application from a
+widget file:
+
+    dbus-send --session --print-reply \
+        --dest=org.AGL.afm.system \
+        /org/AGL/afm/system \
+        org.AGL.afm.system.install 'string:"/tmp/appli.wgt"
+
+
+And here, to query data on installed applications that can be run:
+
+    dbus-send --session --print-reply \
+        --dest=org.AGL.afm.user \
+        /org/AGL/afm/user \
+        org.AGL.afm.user.runnables string:true
+
+### The protocol over D-Bus
+
+On all following sub-chapters we assume that we talk about either
+***afm-system-daemon*** or ***afm-user-daemon***. Method and D-Bus parameters
+are considered as self-explanatory.
+
+The D-Bus interface is defined by:
+
+ * **DESTINATION**: org.AGL.afm.[user|system]
+
+ * **PATH**: /org/AGL/afm/[user|system]
+
+ * **INTERFACE**: org.AGL.afm.[user|system]
+
+#### Method org.AGL.afm.system.install
+
+**Description**: Install an application from a widget file.
+
+When an application with the same *id* and *version* already exists. Outside of
+using *force=true* the application is not reinstalled.
+
+Applications are installed the subdirectories of applications common directory.
+If *root* is specified, the application is installed under the
+sub-directories of the *root* defined.
+
+Note that this methods is a simple accessor method of
+***org.AGL.afm.system.install*** from ***afm-system-daemon***.
+
+After the installation and before returning to the sender,
+***afm-system-daemon*** sends a signal ***org.AGL.afm.system.changed***.
+
+**Input**: The *path* of the widget file to install and, optionally,
+a flag to *force* reinstallation, and, optionally, a *root* directory.
+
+Either just a string being the absolute path of the widget file:
+
+    "/a/path/driving/to/the/widget"
+
+Or an object:
+
+    {
+      "wgt": "/a/path/to/the/widget",
+      "force": false,
+      "root": "/a/path/to/the/root"
+    }
+
+"wgt" and "root" must be absolute paths.
+
+**output**: An object with the field "added" being the string for
+the id of the added application.
+
+    {"added":"appli@x.y"}
+
+---
+
+#### Method org.AGL.afm.system.uninstall
+
+**Description**: Uninstall an application from its id.
+
+
+Note that this methods is a simple method accessor of
+***org.AGL.afm.system.uninstall*** from ***afm-system-daemon***.
+
+After the uninstallation and before returning to the sender,
+***afm-system-daemon*** sends a signal ***org.AGL.afm.system.changed***.
+
+**Input**: the *id* of the application and optionally the application *root* path.
+
+Either a string:
+
+    "appli@x.y"
+
+Or an object:
+
+    {
+      "id": "appli@x.y",
+      "root": "/a/path/to/the/root"
+    }
+
+**output**: the value 'true'.
+
+---
+
+#### Method org.AGL.afm.user.detail
+
+
+**Description**: Get details about an application from its id.
+
+**Input**: the id of the application as below.
+
+Either just a string:
+
+    "appli@x.y"
+
+Or an object having the field "id" of type string:
+
+    {"id":"appli@x.y"}
+
+**Output**: A JSON object describing the application containing
+the fields described below.
+
+    {
+      "id":          string, the application id (id@version)
+      "version":     string, the version of the application
+      "width":       integer, requested width of the application
+      "height":      integer, resqueted height of the application
+      "name":        string, the name of the application
+      "description": string, the description of the application
+      "shortname":   string, the short name of the application
+      "author":      string, the author of the application
+    }
+
+---
+
+#### Method org.AGL.afm.user.runnables
+
+**Description**: Get the list of applications that can be run.
+
+**Input**: any valid json entry, can be anything except null.
+
+**output**: An array of description of the runnable applications.
+Each item of the array contains an object containing the detail of
+an application as described above for the method
+*org.AGL.afm.user.detail*.
+
+---
+
+#### Method org.AGL.afm.user.install
+
+**Description**: Install an application from its widget file.
+
+If an application of the same *id* and *version* exists, it is not
+reinstalled except when *force=true*.
+
+Applications are installed in the subdirectories of the common directory
+reserved for applications.
+If *root* is specified, the application is installed under
+sub-directories of defined *root*.
+
+Note that this methods is a simple accessor to the method
+***org.AGL.afm.system.install*** of ***afm-system-daemon***.
+
+After the installation and before returning to the sender,
+***afm-user-daemon*** sends the signal ***org.AGL.afm.user.changed***.
+
+**Input**: The *path* of widget file to be installed. Optionally,
+a flag to *force* reinstallation and/or a *root* directory.
+
+Simple form a simple string containing the absolute widget path:
+
+    "/a/path/driving/to/the/widget"
+
+Or an object:
+
+    {
+      "wgt": "/a/path/to/the/widget",
+      "force": false,
+      "root": "/a/path/to/the/root"
+    }
+
+***wgt*** and ***root*** MUST be absolute paths.
+
+**output**: An object containing field "added" to use as application ID.
+
+    {"added":"appli@x.y"}
+
+---
+
+#### Method org.AGL.afm.user.uninstall
+
+**Description**: Uninstall an application from its id.
+
+
+Note that this methods is a simple accessor to
+***org.AGL.afm.system.uninstall*** method from ***afm-system-daemon***.
+
+After the uninstallation and before returning to the sender,
+***afm-user-daemon*** sends the signal ***org.AGL.afm.user.changed***.
+
+**Input**: the *id* of the application and, optionally, the path to
+application *root*.
+
+Either a string:
+
+    "appli@x.y"
+
+Or an object:
+
+    {
+      "id": "appli@x.y",
+      "root": "/a/path/to/the/root"
+    }
+
+**output**: the value 'true'.
+
+---
+
+#### Method org.AGL.afm.user.start
+
+**Description**:
+
+**Input**: the *id* of the application and, optionally, the
+start *mode* as below.
+
+Either just a string:
+
+    "appli@x.y"
+
+Or an object containing field "id" of type string and
+optionally a field mode:
+
+    {"id":"appli@x.y","mode":"local"}
+
+The field "mode" is a string equal to either "local" or "remote".
+
+**output**: The *runid* of the application launched. *runid* is an integer.
+
+---
+
+#### Method org.AGL.afm.user.once
+
+**Description**:
+
+**Input**: the *id* of the application
+
+Either just a string:
+
+    "appli@x.y"
+
+Or an object containing field "id" of type string.
+
+    {"id":"appli@x.y"}
+
+**output**: The *state* of the application retrieved or launched.
+See *org.AGL.afm.user.state* to get a description of the returned
+object.
+
+---
+
+#### Method org.AGL.afm.user.terminate
+
+**Description**: Terminates the application attached to *runid*.
+
+**Input**: The *runid* (an integer) of running instance to terminate.
+
+**output**: the value 'true'.
+
+---
+
+#### Method org.AGL.afm.user.stop
+
+Obsolete since 8th November 2016 (2016/11/08).
+Kept for compatibility.
+
+Use **org.AGL.afm.user.pause** instead.
+
+---
+
+#### Method org.AGL.afm.user.continue
+
+Obsolete since 8th November 2016 (2016/11/08).
+Kept for compatibility.
+
+Use **org.AGL.afm.user.resume** instead.
+
+---
+
+#### Method org.AGL.afm.user.pause
+
+**Description**: Pauses the application attached to *runid* until terminate or resume.
+
+**Input**: The *runid* (integer) of the running instance to pause.
+
+**output**: the value 'true'.
+
+---
+
+#### Method org.AGL.afm.user.resume
+
+**Description**: Resumes the application attached to *runid* previously paused.
+
+**Input**: The *runid* (integer) of the running instance to resume.
+
+**output**: the value 'true'.
+
+---
+
+#### Method org.AGL.afm.user.state
+
+**Description**: Get informations about a running instance of *runid*.
+
+**Input**: The *runid* (integer) of the running instance inspected.
+
+**output**: An object describing instance state. It contains:
+the runid (integer), the pids of the processes as an array starting
+with the group leader, the id of the running application (string),
+the state of the application (string either: "starting", "running", "paused").
+
+Example of returned state:
+
+    {
+      "runid": 2,
+      "pids": [ 435, 436 ],
+      "state": "running",
+      "id": "appli@x.y"
+    }
+
+---
+
+#### Method org.AGL.afm.user.runners
+
+**Description**: Get the list of currently running instances.
+
+**Input**: anything.
+
+**output**: An array of states, one per running instance, as returned by
+the method ***org.AGL.afm.user.state***.
+
+Starting **afm daemons**
+----------------------
+
+***afm-system-daemon*** and ***afm-user-daemon*** are launched as systemd
+services attached to system and user respectively. Normally, service files are
+locatedat */lib/systemd/system/afm-system-daemon.service* and
+*/lib/systemd/user/afm-user-daemon.service*.
+
+### ***afm-system-daemon*** options
+
+The options for launching **afm-system-daemon** are:
+
+    -r
+    --root directory
+   
+         Set the root application directory.
+
+         Note that the default root directory is defined
+         to be /usr/share/afm/applications (may change).
+   
+    -d
+    --daemon
+   
+         Daemonizes the process. It is not needed by sytemd.
+   
+    -q
+    --quiet
+   
+         Reduces the verbosity (can be repeated).
+   
+    -v
+    --verbose
+   
+         Increases the verbosity (can be repeated).
+   
+    -h
+    --help
+   
+         Prints a short help.
+   
+### ***afm-user-daemon*** options
+
+The options for launching **afm-user-daemon** are:
+
+    -a
+    --application directory
+   
+         Includes the given application directory to
+         the database base of applications.
+   
+         Can be repeated.
+   
+    -r
+    --root directory
+   
+         Includes root application directory or directories when
+         passing multiple rootdir to
+         applications database.
+
+         Note that default root directory for
+         applications is always added. In current version
+         /usr/share/afm/applications is used as default.
+       
+    -m
+    --mode (local|remote)
+   
+         Set the default launch mode.
+         The default value is 'local'
+   
+    -d
+    --daemon
+   
+         Daemonizes the process. It is not needed by sytemd.
+   
+    -q
+    --quiet
+   
+         Reduces the verbosity (can be repeated).
+   
+    -v
+    --verbose
+   
+         Increases the verbosity (can be repeated).
+   
+    -h
+    --help
+   
+         Prints a short help.
+
+Tasks of **afm-user-daemon**
+----------------------------
+
+### Maintaining list of applications
+
+At start **afm-user-daemon** scans the directories containing
+applications and load in memory a list of avaliable applications
+accessible by current user.
+
+When **afm-system-daemon** installs or removes an application.
+On success it sends the signal *org.AGL.afm.system.changed*.
+When receiving such a signal, **afm-user-daemon** rebuilds its
+applications list.
+
+**afm-user-daemon** provides the data it collects about
+applications to its clients. Clients may either request the full list
+of avaliable applications or a more specific information about a
+given application.
+
+### Launching application
+
+**afm-user-daemon** launches application. Its builds a secure
+environment for the application before starting it within a
+secured environment.
+
+Different kind of applications can be launched.
+
+This is set using a configuration file that describes
+how to launch an application of a given kind within a given
+mode.
+
+There is two launching modes: local or remote.
+
+Launching an application locally means that
+the application and its binder are launched together.
+
+Launching application remotely translates in only launching
+the application binder. The UI by itself has to be activated
+remotely by the requested (ie: HTML5 homescreen in a browser)
+
+Once launched, running instances of application receive
+a runid that identify them.
+
+### Managing instances of running applications
+
+**afm-user-daemon** manages the list of applications
+that it launched.
+
+When owning the right permissions, a client can get the list
+of running instances and details about a specific
+running instance. It can also terminate, pause or
+resume a given application.
+
+### Installing and uninstalling applications
+
+If the client own the right permissions,
+**afm-user-daemon** delegates that task
+to **afm-system-daemon**.
+
+Launcher Configuration
+----------------------
+
+It contains rules for launching applications.
+When **afm-user-daemon** has to launch an application,
+it looks for launch mode (local or remote), as well as
+for the type of application describe in ***config.xml***
+widget configuration file.
+
+This tuple mode+type allows to select the adequate rule.
+
+Configuration file is **/etc/afm/afm-launch.conf**.
+
+It contains sections and rules. It can also contain comments
+and empty lines to improve readability.
+
+The separators are space and tabulation, any other character
+should have a meaning.
+
+The format is line oriented.
+The new line character separate the lines.
+
+Lines having only separators are blank lines and ignored.
+Line having character #(sharp) at first position are comment
+lines and ignored.
+
+Lines not starting with a separator are different
+from lines starting with a separator character.
+
+The grammar of the configuration file is defined below:
+
+    CONF: *COMMENT *SECTION
+   
+    SECTION: MODE *RULE
+   
+    RULE: +TYPE VECTOR ?VECTOR
+   
+    MODE: 'mode' +SEP ('local' | 'remote') *SEP EOL
+   
+    TYPE: DATA *SEP EOL
+   
+    VECTOR: +SEP DATA *(+SEP NDATA) *SEP EOL
+   
+    DATA: CHAR *NCHAR
+    NDATA: +NCHAR
+
+    EOL: NL *COMMENT
+    COMMENT: *SEP CMT *(SEP | NCHAR) NL
+
+    NL: '\x0a'
+    SEP: '\x20' | '\x09'
+    CMT: '#'
+    CHAR: '\x00'..'\x08' | '\x0b'..'\x1f' | '\x21' | '\x22' | '\x24'..'\xff'
+    NCHAR: CMT | CHAR
+   
+Here is a sample of configuration file for defining how
+to launch an application of types *application/x-executable*,
+*text/x-shellscript* and *text/html* in local mode:
+
+    mode local
+   
+    application/x-executable
+    text/x-shellscript
+        %r/%c
+   
+    text/html
+        /usr/bin/afb-daemon --mode=local --readyfd=%R --alias=/icons:%I --port=%P --rootdir=%r --token=%S --sessiondir=%D/.afb-daemon
+        /usr/bin/web-runtime http://localhost:%P/%c?token=%S
+
+This shows that:
+
+ - within a section, several rules can be defined
+ - within a rule, several types can be defined
+ - within a rule, one or two vectors can be defined
+ - vectors are using %substitution
+ - launched binaries must be defined with their full path
+
+### mode local
+
+Within this mode, the launchers have either one or two description vectors.
+All of those vectors are treated as programs
+and are executed with 'execve' system call.
+
+The first vector is the leader vector and it defines the process
+group. The second vector (if any) is attached to the group
+defined by this first vector.
+
+### mode remote
+
+Within this mode, the launchers have either one or two vectors
+describing them.
+
+The first vector is process as a program and is executed with
+system call 'execve'.
+
+The second vector (if any) defines a text that is returned
+to the caller. This mechanism can be used to return a uri
+for remote UI to connect on the newly launched application.
+
+The daemon ***afm-user-daemon*** allocates a port for each
+new remote application.
+The current implementation port allocation is incremental.
+A smarter (cacheable and discoverable) allocation should be defined.
+
+### %substitutions
+
+Vectors can include sequences of 2 characters that have a special
+meaning. These sequences are named *%substitution* because their
+first character is the percent sign (%) and because each occurrence
+of the sequence is replaced, at launch time, by the value associated
+to sequences.
+
+Here is the list of *%substitutions*:
+
+ - ***%%***: %.
+
+   This simply emits the percent sign %
+
+ - ***%a***: appid
+
+   Holds application Id of launched application.
+
+   Defined by the attribute **id** of the element **<widget>**
+   of **config.xml**.
+
+ - ***%b***: bindings
+
+   In the future should represent the list of bindings and bindings directory separated by ','.
+   Warning: not supported in current version.
+
+ - ***%c***: content
+
+   The file within the widget directory that is the entry point.
+
+   For HTML applications, it represents the relative path to main
+   page (aka index.html).
+
+   Defined by attribute **src** of the element **<content>** within **config.xml**.
+
+ - ***%D***: datadir
+
+   Path of the directory where the application runs (cwd)
+   and stores its data.
+
+   It is equal to %h/%a.
+
+ - ***%H***: height
+
+   Requested height for the widget.
+
+   Defined by the attribute **height** of the element **<widget>**
+   of **config.xml**.
+
+ - ***%h***: homedir
+
+   Path of the home directory for all applications.
+
+   It is generally equal to $HOME/app-data
+
+ - ***%I***: icondir
+
+   Path of the directory were the icons of the applications can be found.
+
+ - ***%m***: mime-type
+
+   Mime type of the launched application.
+
+   Defined by the attribute **type** of the element **<content>**
+   of **config.xml**.
+
+ - ***%n***: name
+
+   Name of the application as defined by the content of the
+   element **<name>** of **config.xml**.
+
+ - ***%P***: port
+
+   A port to use. It is currently a kind of random port. The precise
+   model is to be defined later.
+
+ - ***%R***: readyfd
+
+   Number of file descriptor to use for signaling
+   readiness of launched process.
+
+ - ***%r***: rootdir
+
+   Path of directory containing the widget and its data.
+
+ - ***%S***: secret
+
+   An hexadecimal number that can be used to initialize pairing of client
+   and application binder.
+
+ - ***%W***: width
+
+   Requested width for the widget.
+
+   Defined by the attribute **width** of the element **<widget>**
+   of **config.xml**.
+
+Using ***afm-util***
+--------------------
+
+The command line tool ***afm-util*** uses dbus-send to send
+orders to **afm-user-daemon**. This small scripts allows to
+send command to ***afm-user-daemon*** either interactively
+at shell prompt or scriptically.
+
+The syntax is simple: it accept a command and when requires attached arguments.
+
+Here is the summary of ***afm-util***:
+
+ - **afm-util runnables      **:
+
+   list the runnable widgets installed
+
+ - **afm-util install    wgt **:
+
+   install the wgt file
+
+ - **afm-util uninstall  id  **:
+
+   remove the installed widget of id
+
+ - **afm-util detail     id  **:
+
+   print detail about the installed widget of id
+
+ - **afm-util runners        **:
+
+   list the running instance
+
+ - **afm-util start      id  **:
+
+   start an instance of the widget of id
+
+ - **afm-util once      id  **:
+
+   run once an instance of the widget of id
+
+ - **afm-util terminate  rid **:
+
+   terminate the running instance rid
+
+ - **afm-util pause       rid **:
+
+   pause the running instance rid
+
+ - **afm-util resume   rid **:
+
+   resume the previously paused rid
+
+ - **afm-util state      rid **:
+
+   get status of the running instance rid
+
+
+Here is how to list applications using ***afm-util***:
+
+    afm-util runnables
+
+
+[afm-daemons]: pictures/afm-daemons.svg "afm daemons location in the system"