If your plug-in defines and manipulates its own resource types, you may have special requirements for searching a resource. For example, the Java IDE plug-in implements a search engine specialized for Java files.
The search plug-in allows you to add a specialized page describing your search to the workbench search dialog. This allows you to correct any specialized information needed from the user and perform a search using your plug-ins internal model.
Once the search results are found, you may also provide a specialized class for sorting the search results in the search results view.
Both of these services are provided using search plug-in extension points.