There was some confusing mentions about composite applications in the cloud at the PDC 2010, but we haven’t heard much about it since then.
Last month Itai Raz from the Windows Azure AppFabric Team wrote a blog about Composite Applications in AppFabric.
Like many I didn’t fully understand where that product was going at the PDC 2010. But now it makes more sense.
It’s basically a way to model your application at a high level (e.g. I want web role, caching and a DB) and deploy it in AppFabric. AppFabric knows how your application is built and can therefore monitor it and allow you to change some aspects of it at runtime.
In many ways, it is what Azure Hosting (the basic Windows Azure) does, but on steroids. Windows Azure already has an abstraction above your processes. It knows about the roles you deploy so it can move them around in time. Well, Composite App is a step up in that model.
On the other hand, you can consider Composite App as a cloud extension of what Windows Server AppFabric does: hosts WCF + WF, monitor, etc.
It is looking like AppFabric really is lifting of to become a core of Microsoft’s cloud platform: compare the following picture to last year’s (when we only had the first two services) and you’ll see where the investment is going.