At work, we currently have a WSDL interface as well as a semi-RESTful interface that we're looking to expand upon and take it to the next level.

The main application runs using Servlets + JSPs as well as Spring.

The idea is that the REST and WSDL are interfaces for an API that will be designed. These (and potentially other things in future) are simply a method through which clients will be able to integrate with the interface.

I'm wondering if there are any suggestions or recommendations on frameworks / methodologies, etc for implementing that under-lying API or does it make sense simply to create some Spring beans which is called either by WSDL or REST?

Hope that makes sense.