Widget configuration file - config.xml

The packages have a structure similar to the structure of the widget as described by the W3C’s technical recommendations Packaged Web Apps (Widgets) and XML Digital Signatures for Widgets that specifies the configuration file config.xml.

Overview

The file config.xml describes important data of the application to the framework:

  • the unique identifier of the application
  • the name of the application
  • the type of the application
  • the icon of the application
  • the permissions linked to the application
  • the services and dependencies of the application

The file MUST be at the root of the package and MUST be case sensitively name config.xml.

The file config.xml is a XML file described by the document widgets.

Here is the example of the config file for the QML application SmartHome.

<?xml version="1.0" encoding="UTF-8"?>
<widget xmlns="http://www.w3.org/ns/widgets" id="smarthome" version="0.1">
  <name>SmartHome</name>
  <icon src="smarthome.png"/>
  <content src="qml/smarthome/smarthome.qml" type="text/vnd.qt.qml"/>
  <description>This is the Smarthome QML demo application. It shows some user interfaces for controlling an
automated house. The user interface is completely done with QML.</description>
  <author>Qt team</author>
  <license>GPL</license>
</widget>

The most important items are:

  • <widget id=”……”>: gives the id of the package. It must be unique.

  • <widget version=”……”>: gives the version of the package

  • <icon src=”…”>: gives a path to the icon of the application (can be repeated with different sizes)

  • <content src=”…” type=”…”>: this indicates the entry point and its type.

Standard elements of “config.xml”

The element package

the attribute id of package

The attribute id is mandatory (for version 2.x, blowfish) and must be unique.

Values for id are any non empty string containing only latin letters, arabic digits, and the three characters ‘.’ (dot), ‘-‘ (dash) and ‘_’ (underscore).

Authors can use a mnemonic id or can pick a unique id using command uuid or uuidgen.

the attribute version of package

The attribute version is mandatory (for version 2.x, blowfish).

Values for version are any non empty string containing only latin letters, arabic digits, and the three characters ‘.’ (dot), ‘-‘ (dash) and ‘_’ (underscore).

Version values are dot separated fields MAJOR.MINOR.REVISION. Such version would preferably follow guidelines of semantic versioning.

The element content

The element content is mandatory (for version 2.x, blowfish) and must designate a file (subject to localization) with its attribute src.

The content designed depends on its type. See below for the known types.

The element icon

The element icon is mandatory (for version 2.x, blowfish) and must be unique. It must designate an image file with its attribute src.

AGL features

The AGL framework uses the feature tag for specifying security and binding requirement of the package.

Since the migration of the framework to leverage systemd power, the features are of important use to:

  • declare more than just an application
  • declare the expected dependencies
  • declare the expected permissions
  • declare the exported apis

The specification of widgets is intended to describe only one application. In the present case, we expect to describe more than just an application. For example, a publisher could provide a package containing a service, an application for tuning that service, an application that leverage the service. Here, the term of service means a background application that runs without IHM and whose public api can be accessed by other applications.

So the features are used to describe each of the possible units of packages. The “standard” unit in the meaning of widgets is called the “main” unit.

required-api: feature name=”urn:AGL:widget:required-api”

List of the api required by the package.

Each required api must be explicit using a <param> entry.

Example:

<feature name="urn:AGL:widget:required-api">
  <param name="#target" value="main" />
  <param name="gps" value="auto" />
  <param name="afm-main" value="link" />
</feature>

This will be virtually translated for mustaches to the JSON

"required-api": [
   { "name": "gps", "value": "auto" },
   { "name": "afm-main", "value": "link" }
 ]

required-api: param name=”#target”

OPTIONAL

Declares the name of the unit requiring the listed apis. Only one instance of the param “#target” is allowed. When there is not instance of this param, it behave as if the target main was specified.

required-api: param name=[required api name]

The name is the name of the required API.

The value describes how to connect to the required api. It is either:

  • auto: The framework set automatically the kind of the connection to the API

  • ws: The framework connect using internal websockets

  • dbus: [OBSOLETE, shouldn’t be used currently] The framework connect using internal dbus

  • tcp: In that case, the name is the URI to access the service. The framework connect using a URI of type HOST:PORT/API API gives the name of the imported api.

  • cloud: [PROPOSAL - NOT IMPLEMENTED] The framework connect externally using websock. In that case, the name includes data to access the service. Example: <param name="log:https://oic@agl.iot.bzh/cloud/log" value="cloud" />

required-binding: feature name=”urn:AGL:widget:required-binding”

List of the bindings required by the package.

Note: Since AGL 6 (FF - Funky Flounder), the binder implements bindings version 3 that allow the declaration of 0, 1 or more APIs by one binding. In other words, the equivalency one binding = one API is lost. At the same time the framework added the ability to use bindings exported by other packages.

Each required binding must be explicit using a <param> entry.

Example:

<feature name="urn:AGL:widget:required-binding">
  <param name="libexec/binding-gps.so" value="local" />
  <param name="extra" value="extern" />
</feature>

This will be virtually translated for mustaches to the JSON

"required-binding": [
   { "name": "libexec/binding-gps.so", "value": "local" },
   { "name": "extra", "value": "extern" }
 ]

required-binding: param name=[name or path]

The name or the path of the required BINDING.

The value describes how to connect to the required binding. It is either:

  • local: The binding is a local shared object. In that case, the name is the relative path of the shared object to be loaded.

  • extern: The binding is external. The name is the exported binding name. See provided-binding.

provided-binding: feature name=”urn:AGL:widget:provided-binding”

This feature allows to export a binding to other binders. The bindings whose relative name is given as value is exported to other binders under the given name.

Each provided binding must be explicit using a <param> entry.

Example:

<feature name="urn:AGL:widget:provided-binding">
  <param name="extra" value="export/binding-gps.so" />
</feature>

This will be virtually translated for mustaches to the JSON

"provided-binding": [
   { "name": "extra", "value": "export/binding-gps.so" }
 ]

provided-binding: param name=[exported name]

Exports a local binding to other applications.

The value must contain the path to the exported binding.

required-permission: feature name=”urn:AGL:widget:required-permission”

List of the permissions required by the unit.

Each required permission must be explicit using a <param> entry.

Example:

  <feature name="urn:AGL:widget:required-permission">
    <param name="#target" value="geoloc" />
    <param name="urn:AGL:permission:real-time" value="required" />
    <param name="urn:AGL:permission:syscall:*" value="required" />
  </feature>

This will be virtually translated for mustaches to the JSON

"required-permission":{
  "urn:AGL:permission:real-time":{
    "name":"urn:AGL:permission:real-time",
    "value":"required"
  },
  "urn:AGL:permission:syscall:*":{
    "name":"urn:AGL:permission:syscall:*",
    "value":"required"
  }
}

required-permission: param name=”#target”

OPTIONAL

Declares the name of the unit requiring the listed permissions. Only one instance of the param “#target” is allowed. When there is not instance of this param, it behave as if the target main was specified.

required-permission: param name=[required permission name]

The value is either:

  • required: the permission is mandatorily needed except if the feature isn’t required (required=”false”) and in that case it is optional.
  • optional: the permission is optional

provided-unit: feature name=”urn:AGL:widget:provided-unit”

This feature is made for declaring new units for the package. Using this feature, a software publisher can provide more than one application in the same package.

Example:

  <feature name="urn:AGL:widget:provided-unit">
    <param name="#target" value="geoloc" />
    <param name="description" value="binding of name geoloc" />
    <param name="content.src" value="index.html" />
    <param name="content.type" value="application/vnd.agl.service" />
  </feature>

This will be virtually translated for mustaches to the JSON

    {
      "#target":"geoloc",
      "description":"binding of name geoloc",
      "content":{
        "src":"index.html",
        "type":"application\/vnd.agl.service"
      },
      ...
    }

provided-unit: param name=”#target”

REQUIRED

Declares the name of the unit. The default unit, the unit of the main of the package, has the name “main”. The value given here must be unique within the widget file. It will be used in other places of the package config.xml file to designate the unit.

Only one instance of the param “#target” is allowed. The value can’t be “main”.

provided-unit: param name=”content.type”

REQUIRED

The mimetype of the provided unit.

provided-unit: param name=”content.src”

A path to the source

other parameters

The items that can be set for the main unit can also be set using the params if needed.

  • description
  • name.content
  • name.short
  • …

provided-api: feature name=”urn:AGL:widget:provided-api”

Use this feature for exporting one or more API of a unit to other packages of the platform.

This feature is an important feature of the framework.

Example:

  <feature name="urn:AGL:widget:provided-api">
    <param name="#target" value="geoloc" />
    <param name="geoloc" value="auto" />
    <param name="moonloc" value="auto" />
  </feature>

This will be virtually translated for mustaches to the JSON

      "provided-api":[
        {
          "name":"geoloc",
          "value":"auto"
        },
        {
          "name":"moonloc",
          "value":"auto"
        }
      ],

provided-api: param name=”#target”

OPTIONAL

Declares the name of the unit exporting the listed apis. Only one instance of the param “#target” is allowed. When there is not instance of this param, it behave as if the target main was specified.

provided-api: param name=[name of exported api]

The name give the name of the api that is exported.

The value is one of the following values:

  • ws: export the api using UNIX websocket

  • dbus: [OBSOLETE, shouldn’t be used currently] export the API using dbus

  • auto: export the api using the default method(s).

  • tcp: In that case, the name is the URI used for exposing the service. The URI is of type HOST:PORT/API API gives the name of the exported api.

file-properties: feature name=”urn:AGL:widget:file-properties”

Use this feature for setting properties to files of the package. At this time, this feature only allows to set executable flag for making companion program executable explicitly.

Example:

  <feature name="urn:AGL:widget:file-properties">
    <param name="flite" value="executable" />
    <param name="jtalk" value="executable" />
  </feature>

file-properties: param name=”path”

The name is the relative path of the file whose property must be set.

The value must be “executable” to make the file executable.