The Eclipse platform is structured so that you can develop a workbench application even if your application has nothing to do with the platform resource model. However, the workbench does provide support for working with resources in a separate plug-in, org.eclipse.ui.ide. This plug-in contains the parts of the SDK workbench that focus on IDE building and manipulating the workspace.
If your plug-in uses the platform resource model, you may want to take advantage of the resource-oriented features in the workbench. These include resource property pages, resource marker UI, resource filtering, and other utilities.