The afm-system-daemon

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

TABLE-OF-CONTENT-HERE

Foreword

This document describes application framework system daemon fundamentals. FCF (Fully Conform to Specification) implementation is still under development. It may happen that current implementation somehow diverges with specifications.

Introduction

The daemon afm-system-daemon is in charge of installing applications on AGL system. Its main tasks are:

• installs applications and setup security framework for newly installed application.

• uninstall applications

The afm-system-daemon takes its orders from system instance of D-Bus.

The figure below summarizes the situation of afm-system-daemon in the system.

+------------------------------------------------------------+
|                          User                              |
|                                                            |
|     +-------------------------------------------------+    |
|     |                                                 |    |
|     |                  afm-user-daemon                |    |
|     |                                                 |    |
|     +----------+----------------------+----------+----+    |
|                |                      |          :         |
|                |                      |          :         |
:================|======================|==========:=========:
|                |                      |          :         |
|     +----------+----------+     +-----+-----+    :         |
|     |   D-Bus   system    +-----+  CYNARA   |    :         |
|     +----------+----------+     +-----+-----+    :         |
|                |                      |          :         |
|     +----------+---------+    +-------+----------+----+    |
|     | afm-system-daemon  +----+   SECURITY-MANAGER    |    |
|     +--------------------+    +-----------------------+    |
|                                                            |
|                          System                            |
+------------------------------------------------------------+

Starting afm-system-daemon

afm-system-daemon is launched as a systemd service attached to system. Normally, the service file is located at /lib/systemd/system/afm-system-daemon.service.

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.

The D-Bus interface

Overview of the dbus interface

afm-system-daemon takes its orders from the session instance of D-Bus. The use of D-Bus is great because it allows to implement discovery and signaling.

The afm-system-daemon is listening with the destination name org.AGL.afm.system at the object of path /org/AGL/afm/system on the interface org.AGL.afm.system for the below detailed members install and 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.

The D-Bus interface is defined by:

• DESTINATION: org.AGL.afm.system

• PATH: /org/AGL/afm/system

• INTERFACE: org.AGL.afm.system

The signature of any member of the interface is string -> string for JSON -> JSON.

This is the normal case. In case of error, the current implementation returns a dbus error that is a string.

Here is an example using dbus-send to query data on installed applications.

dbus-send --session --print-reply \
    --dest=org.AGL.afm.system \
    /org/AGL/afm/system \
    org.AGL.afm.system.install 'string:"/tmp/appli.wgt"'

The protocol over D-Bus

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'.