From our website (http://isis.apache.org):
Apache Isis™ software is a framework for rapidly developing domain-driven apps in Java. Write your business logic in entities, domain services and repositories, and the framework dynamically generates a representation of that domain model as a webapp or a RESTful API. Use for prototyping or production.
Isis works by building a metamodel from the domain object models, from which a generic user interface is generated dynamically at runtime. There are several implementations of the generic UI, one based on Wicket, one based on Servlet/JSPs, and one based on jax-rs and serving up a Restful API over http and json. This API is fully documented in the Restful Objects spec (http://restfulobjects.org) ... there is also a (non-Apache) open source implementation on .NET.
This GSOC suggestion is to develop a generic viewer using Apache Flex that will consume the RESTful API provided by Isis. Optionally this generic viewer could be extensible to allow mashups (as is supported by Isis' own Wicket-based viewer).