Meaning of plugin.xml
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The plugin.xml#

The d3web software makes heavy use of plugins to extend its functionalities, using the JPF plugin-framework (JPF). The plugins need to be configured using plugin.xml files in each binary project (jar-archive).

See also How-To Extension Points for more details on writing your own extensions.

Add extensions using an existing extension-point#

A plugin can define new extension points, but can also extend existing extension points of other plugins. The defined extension point specifies that each extension has to give values for class, name, description, version, and priority. This has to be defined by each extension point; an extension point further can require additional value, for example the specification of a file name.

This plugin has the ID de.d3web.casepersistence and defines the ExtensionPoint "CasePersistenceHandler". In general, a plugin can define multiple extension points. Within the plugin, the IDs of the extension points have to be unique. However, two different plugins may use the same ID for different extension points, since the ID of an extension point is always evaluated together with the ID of the plugin. This is shown by the following extension of the extension point above: 

<?xml version="1.0" ?>
<!DOCTYPE plugin PUBLIC "-//JPF//Java Plug-in Manifest 1.0" "http://jpf.sourceforge.net/plugin_1_0.dtd">
<plugin id="de.d3web.casepersistence.basic" version="0.0.1">
	
	<requires>
		<import plugin-id="de.d3web.cpers.xml" />
	</requires>
	
	<runtime>
		<library id="de.d3web.cpers.xml" path="." type="code">
			<export prefix="*" />
		</library>
	</runtime>
	
	<extension plugin-id="de.d3web.casepersistence" point-id="CasePersistenceHandler"
		id="FactHandler">
		<parameter id="class"
			value="de.d3web.cpers.xml.FactHandler" />
		<parameter id="name" value="FactHandler" />
		<parameter id="description" value="Handler for facts" />
		<parameter id="version" value="1.0" />
		<parameter id="priority" value="5" />
	</extension>
	
</plugin>

Define new extension-points#

A minimalistic example defining only one ExtensionPoint is given as follows: 

<?xml version="1.0" ?>
<!DOCTYPE plugin PUBLIC "-//JPF//Java Plug-in Manifest 1.0" "http://jpf.sourceforge.net/plugin_1_0.dtd">
<!-- This plugin only defines extension points for CasePersistenceHandler and CaseConversionHandler. -->
<plugin id="de.d3web.casepersistence" version="0.0.1">
	
	<extension-point id="CasePersistenceHandler">
		<parameter-def id="class" />
		<parameter-def id="name" />
		<parameter-def id="description" />
		<parameter-def id="version" />
		<parameter-def id="priority" type="number" />
	</extension-point>
	
</plugin>