...
The following figure illustrates the basic steps that are required to make a plugin extendable (consumer) and to create an extension for it (provider):
...
The extension service interfaces must be registered at the consumer and provider component. The following figure shows the workflow of an example of an extension for the GX Books Example plugin. The extension (provider) extends the findBooks() method of the consumer further by searching web sites and other databases for books when a user executes a search:
Alternate View Extension Example
...