And there is another important layer missing from the stack, the persistence layer, and Grey Lens Man is still looking for a solution.
Both the client and the server have an object persistence layer that reads and writes objects to the local database.
That introduced strong awareness of the persistence layer spoiling the domain model.
Many runtime production performance issues are tracked down to the persistence layer, and having a properly optimized database and data access layer is of utmOSt importance.
Multiple converted OSGi bundles, separating web and data persistence layers.
But don't try to create a generic, all-purpose persistence layer, since at this point you're not sure you need it.
