A DITA-OT plug-in can be dependent on other plug-ins. Prerequisite plug-ins are installed first, which ensures that the DITA-OT handles XSLT overrides correctly.
<require> element in the plugin.xml file specifies whether the
plug-in has dependencies. Use
<require> elements to specify prerequisite plug-ins, in
order from most general to most specific.
If a prerequisite plug-in is missing, the DITA-OT prints a warning during installation. To suppress the warning
but keep the installation order if both plug-ins are present, add
importance="optional" to the
If a plug-in can depend on any one of several optional plug-ins, separate the plug-in IDs with a vertical bar.
This is most useful when combined with
Example: Plug-in with a prerequisite plug-in
The following plug-in will only be installed if the plug-in with the ID
available. If that plug-in is not available, a warning is generated and the installation operation fails.
<plugin id="com.example.builds-on-primary"> <!-- ... Extensions here --> <require plugin="com.example.primary"/> </plugin>
Example: Plug-in that has optional plug-ins
The following plug-in will only be installed if either the plug-in with the ID
pluginA or the
plug-in with the ID
pluginB is available. If neither of those plug-ins are installed, a warning
is generated but the installation operation is completed.
<plugin id="pluginC"> <!-- ...extensions here --> <require plugin="pluginA|pluginB" importance="optional"/> </plugin>