I posted about SCA previously. My take on it is, SCA isn't really about interop. But many people think it is, so I post about it here, on the interop blog.
Sometimes people ask me to compare SCA with what Microsoft offers. Here's my take.
A large part of SCA is oriented toward consolidating the disparate communications models and APIs within Java. Java does remoting with RMI and RMI/IIOP; web-services via JAX-RPC or JAX-WS; asynchronous invocation with JMS; JCA for packaged apps, and so on. Lots of communication models. SCA proposes to unify them. Within the SCA family, the spec covering Java annotations and APIs, and the spec covering Java component implementation specifically deal with this.
Microsoft views this part of SCA as a big endorsement of the approach we have taken in Windows Communication Foundation, part of the .NET Framework v3.0 that shipped in December 2006. WCF consolidates various disparate communications models in .NET into one generalized programming model, with support for interop protocols (WS-* or web-oriented services), binary optimizations, reliable or asynchronous messaging, pub/sub, and others. Because of the clear value for customers in simplifying communications, WCF is the leading model in the industry for communications frameworks. Unlike SCA, WCF is not a spec; WCF is available now (a free download), and is currently being used in production applications. and, the performance of WCF apps, rocks!
Some of SCA goes beyond the basic communication plumbing, and attempts to address the larger and more complex issues surrounding the description, modeling, assembly and management of distributed systems. These are hard problems; Microsoft has been working in this area for many years, and steadily delivering infrastructure to address customer needs. For example, is shipping technology. In the .NET Framework 3.5, we'll deliver integration between WCF and WF, and the version of Visual Studio mated to .NET 3.5, Visual Studio 2008, will provide modeling tools to truly democratize the construction and deployment of conversational service-oriented applications. System Center 2007, currently shipping, enables management of distributed applications. We expect to continue to steadily deliver evolutionary innovations in these areas over time.