Extensions manager ideas

[Adam Hooper <adamh densi com>]

Before coding I'll post my planned code for the Epiphany extensions 
manager (both UI and backend). If anybody has any comments about these 
ideas, please let me know.

First of all, the UI: a dialog with a GtkTreeView and some text 
underneath. The GtkTreeView will be a simple table, each row containing 
two elements: a checkbox (loaded/unloaded) and the extension name. The 
text underneath will show metadata about the selected extension in the 
treeview -- description, author(s), relevant URLs, etc. This is somewhat 
inspired by Gaim's "Plugins" config section, but of course there's 
simply Less Useless Stuff.

I've attached a mockup.

Next... the backend.

Epiphany's extensions manager will scan a hard-coded set of directories 
-- $PREFIX/lib/epiphany/extensions and $EPHY_DOT_DIR/extensions -- for 
XML files which contain metadata about extensions. An example XML file:

-----
error-viewer-extension.xml
-----
<?xml version="1.0" encoding="UTF-8"?>
<extension-list>
        <extension>
                <filename>errorviewer</filename>
                <name>Error Viewer</name>
                <description>Provides a dialog which displays web page 
errors.</description>
                <version>1.1.3</version>
                <author>
                        <name>Adam Hooper</name>
                        <email>adamh densi com</email>
                </author>

<url>http://www.gnome.org/projects/epiphany/extensions</url>
        </extension>
</extension-list>
-----

The extensions manager will parse all these XML files and store them in 
an internal GList. Maybe at some point we can even monitor the 
directories and update the internal GList as new extensions are added.

The extensions manager will also monitor a GConf value -- 
/apps/epiphany/general/loaded_extensions (a List) -- to determine which 
extensions to load. The list will be a list of the desired <filename> 
values from the above XML file. The extensions which appear in that 
GConf list will be loaded; the ones which don't won't. Extensions which 
appear in GConf but have no matching XML file will be silently ignored.

To clarify: the extensions manager UI will *only* use these XML 
definition files. The actual backend will *only* use the GConf value.

To load an extension with filename $filename, the extensions manager 
will look for $EPHY_DOT_DIR/lib${filename}extension.so or 
$PREFIX/lib/epiphany/extensions/lib${filename}extension.so. If a match 
is found, that extension will be loaded (as it is in current Epiphany). 
If not, a WARNING will be printed to the console.

For both the XML files and the .so's, $EPHY_DOT_DIR/extensions will take 
precedence over $PREFIX/lib/epiphany/extensions.



So, the big questions: is there anything I'm forgetting? Any comments? 
Is this system overkill? Any ideas on how to make this system better? etc.

--
Adam Hooper
adamh densi com

<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema";>
	<xsd:annotation>
		<xsd:documentation xml:lang="en">
			Epiphany Web Browser extension metadata schema.
			Copyright (c) 2004 Adam Hooper
		</xsd:documentation>
	</xsd:annotation>

	<xsd:element name="extension-list" type="ExtensionListType"/>

	<xsd:complexType name="ExtensionListType">
		<xsd:annotation>
			<xsd:documentation xml:lang="en">
				List of extensions. Each extension has its set
				of metadata.
			</xsd:documentation>
		</xsd:annotation>
		<xsd:sequence>
			<xsd:element name="extension"
				     type="ExtensionType"
				     minOccurs="1"/>
		</xsd:sequence>
	</xsd:complexType>

	<xsd:complexType name="ExtensionType">
		<xsd:annotation>
			<xsd:documentation xml:lang="en">
				Metadata about an extension.
			</xsd:documentation>
		</xsd:annotation>
		<xsd:sequence>
			<xsd:element name="filename"
				     type="ExtensionFilenameType"
				     minOccurs="1" maxOccurs="1"/>
			<xsd:element name="name"
				     type="xsd:string"
				     minOccurs="1" maxOccurs="1"/>
			<xsd:element name="description"
				     type="xsd:string"
				     minOccurs="1" maxOccurs="1"/>
			<xsd:element name="version"
				     type="xsd:string"
				     maxOccurs="1"/>
			<xsd:element name="author" type="AuthorType"/>
			<xsd:element name="url" type="xsd:anyURI"/>
		</xsd:sequence>
	</xsd:complexType>

	<xsd:simpleType name="ExtensionFilenameType">
		<xsd:annotation>
			<xsd:documentation xml:lang="en">
				The &quot;core&quot; of the extension's
				filename. For example, use &quot;gestures&quot;
				for an extension with a shared object name of
				&quot;libgesturesextension.so&quot;.
			</xsd:documentation>
		</xsd:annotation>
		<xsd:restriction base="xsd:string">
			<xsd:pattern value="[a-zA-Z0-9_-]+"/>
		</xsd:restriction>
	</xsd:simpleType>

	<xsd:complexType name="AuthorType">
		<xsd:annotation>
			<xsd:documentation xml:lang="en">
				An extension author -- a name and (optionally)
				an email address.
			</xsd:documentation>
		</xsd:annotation>
		<xsd:sequence>
			<xsd:element name="name"
				     type="xsd:normalizedString"
				     minOccurs="1" maxOccurs="1"/>
			<xsd:element name="email"
				     type="EmailType"
				     maxOccurs="1"/>
		</xsd:sequence>
	</xsd:complexType>

	<xsd:simpleType name="EmailType">
		<xsd:annotation>
			<xsd:documentation xml:lang="en">
				An email address
			</xsd:documentation>
		</xsd:annotation>
		<xsd:restriction base="xsd:string">
			<xsd:pattern value="[\.a-zA-Z0-9_-]+@([a-zA-Z0-9_-])+(([a-zA-Z0-9_-])*\.([a-zA-Z0-9_-])+)+"/>
		</xsd:restriction>
	</xsd:simpleType>
</xsd:schema>

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