The Command service
The Command service is based on Apache's commons-chain and allows to encapsulate methods to execute as a Command objects
A Command framework Application can create own Catalog of Commands, configuring org.exoplatform.services.command.impl.CommonsXMLConfigurationPlugin as following:
<component>
<key>org.exoplatform.services.command.impl.CommandService</key>
<type>org.exoplatform.services.command.impl.CommandService</type>
<component-plugins>
<component-plugin>
<name>config.catalog</name>
<set-method>addPlugin</set-method>
<type>org.exoplatform.services.command.impl.CommonsXMLConfigurationPlugin</type>
<init-params>
<value-param>
<name>config-file</name>
<value>conf/test-commands.xml</value>
</value-param>
</init-params>
</component-plugin>
</component-plugins>
</component>
Where test-commands.xml is commons-chain standard chain definition xml like:
<catalog>
<command name="addNode"
className="org.exoplatform.frameworks.jcr.command.core.AddNodeCommand"/>
<command name="save"
className="org.exoplatform.frameworks.jcr.command.core.SaveCommand"/>
<command name="setProperty"
className="org.exoplatform.frameworks.jcr.command.core.SetPropertyCommand"/>
</catalog>
CommandService's CommonsXMLConfigurationPlugin uses Apache commons-chain's CatalogFactory instance of which is a singleton for the relevant ClassLoader. For applications that use a thread context class loader (such as web applications running inside a servet container), static getInstance() method will return a separate instance for each application, even if this class is loaded from a shared parent class loader.
Multiple Configuration and Multiple Catalogs:
There is one default Catalog (exposed as element catalog without "name" attribute, as in example above) and it is possible to configure named Catalogs (like catalog name="my-name"). Each Catalog's configuration can be added in different CommonsXMLConfigurationPlugin entries.
For instance, you can have a plugin configuration like:
........
<type>org.exoplatform.services.command.impl.CommonsXMLConfigurationPlugin</type>
<init-params>
<value-param>
<name>config-file</name>
<value>conf/test-commands1.xml</value>
</value-param>
</init-params>
........
with
<catalog>
<command name="save"
className="org.exoplatform.frameworks.jcr.command.core.SaveCommand"/>
</catalog>
inside conf/test-commands1.xml file and
........
<type>org.exoplatform.services.command.impl.CommonsXMLConfigurationPlugin</type>
<init-params>
<value-param>
<name>config-file</name>
<value>conf/test-commands2.xml</value>
</value-param>
</init-params>
........
with
<catalog>
<command name="addNode"
className="org.exoplatform.frameworks.jcr.command.core.AddNodeCommand"/>
</catalog>
inside conf/test-commands2.xml file and at the end you will have both save and addNode commands accessible in the default catalog (the same is valid for named catalogs of course)
