Fundamentally, Riena is about distributing services across tiers. It’s born from a need to have applications that are lighter than rich clients, but more functional and performant than light clients. Applications built on Equinox (like those leveraging Eclipse Rich Client Platform, or OSGi-based server-side applications) are compositions of bundles and services. Equinox services are conceptually similar to web services; they are created, registered, discovered, invoked, deregistered, updated, etc.
One big difference between web services and Equinox services, is that Equinox services tend to be used locally (i.e. within a single JVM). Riena extends this to allow bundles and services to be distributed across tiers by providing a mechanism for creating proxies for OSGi services on the client. Proxies exchange messages and data to server. The true location of the service is transparent to the code that makes use of the services; you talk to the service like it’s local and it takes care of communicating with the real service wherever it lives. Riena includes infrastructure that automatically creates a proxy and connects it to the running service on a remote machine. I assume that it uses the Proxy class in Java to automatically create an instance of the specified interface that knows how to talk to the remote service.
Riena provides some other handy services, like authentication and authorization. The current implementation uses JAAS security for now., but they intend to migrate to Equinox security (which is currently part of the Equinox Incubator) in the future. Authentication is provided via a service that runs on the server, and is exposed to the client (via proxy). Once established, credentials flow from the client to the server automagically as part of the communication. Some infrastructure is provided to manage authorization.
Riena has a “Visual Vision”. Christian showed a user interface that they created for a client. The user interface, coded using Swing (the work began several years ago before they were fully introduced to the wonders of Eclipse Rich Client Platform), shows some interesting user interface concepts. Christian made a good point that, while the flexibility in the “Eclipsey” user interface makes sense to us, end users are often thrown off by it (e.g. how do you get a view back when you close it?). Development of the user interface concepts hasn’t been started in earnest yet, but is on their plan.