add documentation & ideas about config.xml

Also enforce the strings for 'id' and 'version' to be not
empty in config.xml

Change-Id: I510b62891885033e0b750fac5f5de5e0fd25d75d
Signed-off-by: José Bollo <jose.bollo@iot.bzh>

1 files changed, 217 insertions, 0 deletions

diff --git a/doc/writing-config.xml.md b/doc/writing-config.xml.md
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+Writing the configuration file "config.xml"
+===========================================
+
+About "config.xml"
+------------------
+
+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 dependancies of the application
+
+The file MUST be at the root of the widget and MUST be case sensitively name
+***config.xml***.
+
+The file **config.xml** is a XML file described by the document
+[widgets].
+
+Example of "config.xml"
+-----------------------
+
+Here is the example of the config file for the QML application SmartHome.
+
+```xml
+<?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>
+```
+
+Standard elements of "config.xml"
+---------------------------------
+
+### The element widget
+
+#### the attribute id of widget
+
+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 widget
+
+The attribute *version* is mandatory (for version 2.x, blowfish).
+
+Values for *id* 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.
+
+### The element content
+
+The element *content* is mandatory (for version 2.x, blowfish) and must designate a file
+(subject to localisation) 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*.
+
+Known widget types and content
+------------------------------
+
+The configuration file ***/etc/afm/afm-launch.conf*** defines the types
+of widget known and how to launch it.
+
+Known types for the type of content are (for version 2.x, blowfish):
+
+- ***text/html***: 
+   HTML application,
+   content.src designates the home page of the application
+
+- ***application/x-executable***:
+   Native application,
+   content.src designates the relative path of the binary
+
+- ***application/vnd.agl.url***:
+   Internet url,
+   content.src designates the url to be used
+
+- ***application/vnd.agl.service***:
+   AGL service defined as a binder,
+   content.src designates the directory of provided binders,
+   http content, if any, must be put in the subdirectory ***htdocs*** of the widget
+
+- ***application/vnd.agl.native***:
+   Native application with AGL service defined as a binder,
+   content.src designates the relative path of the binary,
+   bindings, if any must be put in the subdirectory ***lib*** of the widget,
+   http content, if any, must be put in the subdirectory ***htdocs*** of the widget
+
+- ***text/vnd.qt.qml***, ***application/vnd.agl.qml***:
+   QML application,
+   content.src designate the relative path of the QML root,
+   imports must be put in the subdirectory ***imports*** of the widget
+
+- ***application/vnd.agl.qml.hybrid***:
+   QML application with bindings,
+   content.src designate the relative path of the QML root,
+   bindings, if any must be put in the subdirectory ***lib*** of the widget,
+   imports must be put in the subdirectory ***imports*** of the widget
+
+- ***application/vnd.agl.html.hybrid***:
+   HTML application,
+   content.src designates the home page of the application,
+   bindings, if any must be put in the subdirectory ***lib*** of the widget,
+   http content must be put in the subdirectory ***htdocs*** of the widget
+
+
+AGL features
+------------
+
+The AGL framework uses the feature tag for specifying security and binding
+requirement of the widget.
+
+The current version of AGL (up to 2.0.1, blowfish) has no fully implemented
+features.
+
+The features planned to be implemented are described below.
+
+### feature name="urn:AGL:provides-binding"
+
+Use this feature for each provided binding of the widget.
+The parameters are:
+
+#### param name="name"
+
+REQUIRED
+
+The value is the string that must match the binding prefix.
+It must be unique.
+
+#### param name="src"
+
+REQUIRED
+
+The value is the path of the shared library for the binding.
+
+#### param name="type"
+
+REQUIRED
+
+Currently it must be ***application/vnd.agl.binding.v1***.
+
+
+#### param name="scope"
+
+REQUIRED
+
+The value indicate the availability of the binidng:
+
+- private: used only by the widget
+- public: available to allowed clients as a remote service (requires permission+)
+- inline: available to allowed clients inside their binding (unsafe, requires permission+++)
+
+#### param name="needed-binding"
+
+OPTIONAL
+
+The value is a space separated list of binding's names that the binding needs.
+
+### feature name="urn:AGL:required-permissions"
+
+List of the permissions required by the widget.
+
+Each required permission must be explicited using a <param> entry.
+
+#### param name=[required permission name]
+
+The value is either:
+
+- required: the permission is really needed.
+- optional: the permission isn't mandatory
+
+### feature name="urn:AGL:defined-permissions"
+
+Each required permission must be explicited using a <param> entry.
+
+#### param name=[defined permission name]
+
+The value is the level of the defined permission:
+
+- system: 
+- platform:
+- partner
+- public:
+
+
+
+
+
+[widgets]:          http://www.w3.org/TR/widgets                                    "Packaged Web Apps"
+[widgets-digsig]:   http://www.w3.org/TR/widgets-digsig                             "XML Digital Signatures for Widgets"
+[libxml2]:          http://xmlsoft.org/html/index.html                              "libxml2"
+[app-manifest]:     http://www.w3.org/TR/appmanifest                                "Web App Manifest"
+