Composite Applications

I've been catching up on some overdue reading this week and got a chance to dig into the MS Architecture Journal issue on composite applications. There is a particularly interesting article that gives a good, broad overview of composite applications and talks about how many of the Microsoft products are supporting the notion of composite applications. The article talks about layers of composition and describes some of the key areas of concern for this type of development. Of interest to me were the layers of Service Composition and End-to-End Composition.

Service Composition is about the ability to compose an application out of existing services by stitching them together via a composition language or tool. This is the relatively typical sample scenario that you see out there for most of the existing tools that attempt to support SOA composition. They allow me to bring in a WSDL from some external source and then utilize that service in an application like an activity in a workflow that I can create in the tool. These type of interactions are relatively simplistic and require some amount of overhead and forgone acceptance of a SOA architecture.

End-To-End Composition is really a superset of Service Composition. This space is a lot more interesting to businesses because this allows them to take a holistic view of their business processes and how they fit into an appliction and how they run in production environments. The ultimate goal here is to allow business type users to be able to visualize their entire system through a composition type of tool and then make modifications to the processes and redeploy portions of their application as well as to have real time views into the running of transactions through their system as a whole. When a business user is able to see what is happening across the set of disparate systems that their business process spans and be able to quickly make modifications to it to streamline processes or inject new steps then they begin to see the power of end to end composition of systems. They can then couple this with tools such as system management and monitoring, data center virtualization, automated provisioning of systems and begin to have real power to manage their businesses. All very cool things.