Overview of AFB-DAEMON

version: 1
Date:    30 mai 2016
Author:  José Bollo

Roles of afb-daemon

The name afb-daemon stands for Application Framework Binder Daemon. That is why afb-daemon is also named the binder.

Afb-daemon is in charge to bind one instance of an application to the AGL framework and AGL system.

On the following figure, you can use a typical use of afb-daemon:

Figure: binder afb-daemon, basis

. . . . . . . . . . . . . . . . . . . . . . . . . .
.        Isolated security context                .
.                                                 .
.        +------------------------------+         .
.        |                              |         .
.        |    A P P L I C A T I O N     |         .
.        |                              |         .
.        +--------------+---------------+         .
.                       |                         .
.                       |                         .
.   +-------------------+----------------------+  .
.   |                            :             |  .
.   |        b i n d e r         :             |  .
.   |    A F B - D A E M O N     :   PLUGINS   |  .
.   |                            :             |  .
.   +-------------------+----------------------+  .
.                       |                         .
. . . . . . . . . . . . | . . . . . . . . . . . . .
                        |
                        v
                   AGL SYSTEM

The application and its companion binder run in secured and isolated environment set for them. Applications are intended to access to AGL system through the binder.

The binder afb-daemon serves multiple purposes:

  1. It acts as a gateway for the application to access the system;

  2. It acts as an HTTP server for serving files to HTML5 applications;

  3. It allows HTML5 applications to have native extensions subject to security enforcement for accessing hardware ressources or for speeding parts of algorithm.

Use cases of the binder afb-daemon

This section tries to give a better understanding of the binder usage through several use cases.

Remotely running application

One of the most interresting aspect of using the binder afb-daemon is the ability to run applications remotely. This feature is possible because the binder afb-daemon implements native web protocols.

So the figure binder, basis would become when the application is run remotely:

Figure: binder afb-daemon and remotely running application

             +------------------------------+
             |                              |
             |    A P P L I C A T I O N     |
             |                              |
             +--------------+---------------+
                            |
                       ~ ~ ~ ~ ~ ~
                      :  NETWORK  :
                       ~ ~ ~ ~ ~ ~
                            |
. . . . . . . . . . . . . . | . . . . . . . . . . . . . .
. Isolated security         |                           .
.   context                 |                           .
.                           |                           .
.     . . . . . . . . . . . . . . . . . . . . . . . .   .
.     .                                             .   .
.     .               F I R E W A L L               .   .
.     .                                             .   .
.     . . . . . . . . . . . . . . . . . . . . . . . .   .
.                           |                           .
.       +-------------------+----------------------+    .
.       |                            :             |    .
.       |    A F B - D A E M O N     :   PLUGINS   |    .
.       |                            :             |    .
.       +-------------------+----------------------+    .
.                           |                           .
. . . . . . . . . . . . . . | . . . . . . . . . . . . . .
                            |
                            v
                       AGL SYSTEM

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.

Offering services to the system

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

This will be used for:

  1. offering common APIs

  2. provide application’s services (services provided as application)

In that case, the figure showing the whole aspects is

Figure: binder afb-daemon for services

. . . . . . . . . . . . . . . . . . . . . . 
.  Isolated security context application  . 
.                                         . 
.    +------------------------------+     . 
.    |                              |     . 
.    |    A P P L I C A T I O N     |     . 
.    |                              |     . 
.    +--------------+---------------+     .     . . . . . . . . . . . . . . . . . . . . . .
.                   |                     .     .        Isolated security context A      .
.                   |                     .     .                                         .
. +-----------------+------------------+  .     . +------------------------------------+  .
. |                        :           |  .     . |                        :           |  .
. |      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     |  .
. +-----------------+------------------+  .     . +-----------------+------------------+  .
.                   |                     .     .                   |                     .
. . . . . . . . . . | . . . . . . . . . . .     . . . . . . . . . . | . . . . . . . . . . .
                    |                                               |
                    v                                               v
         ================================================================================
                                     D - B U S   &   C Y N A R A
         ================================================================================
                    ^                                               ^
                    |                                               |
. . . . . . . . . . | . . . . . . . . . . .     . . . . . . . . . . | . . . . . . . . . . .
.                   |                     .     .                   |                     .
. +-----------------+------------------+  .     . +-----------------+------------------+  .
. |                        :           |  .     . |                        :           |  .
. |      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  |  .
. |                        :     B     |  .     . |                        :     C     |  .
. +------------------------------------+  .     . +------------------------------------+  .
.                                         .     .                                         .
.        Isolated security context B      .     .        Isolated security context C      .
. . . . . . . . . . . . . . . . . . . . . .     . . . . . . . . . . . . . . . . . . . . . .

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.

This simple idea is declined to serves multiple purposes:

  1. add native feature to applications

  2. add common API available by any applications

  3. provide customers services

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