There is a lot of buzz on application networks where applications are stitched together using the functionalities exposed by today's large enterprise systems as web services. Before we start to dream about such application networks we may want to put on our systems engineering hats and ask if we even have the underlying infrastructure to support such networks.
Starting at the lowest layer which is all about computing horsepower and storage capacity. With all the efforts around virtualization and on demand everything, we still don't have a compute or storage grid on which such applications can run.
While Grids find their afficionados in the distributed computing field, the Grid as such is more a network related field. In fact, Grid computing is about decomposing a compute problem into a networking problem. This brings us to the next higher level layer in application networks i.e. the messaging fabric. There is no such thing today. All we have today is a few isolated bridges and routers in the form of MOM middleware but nothing that can remotely be classified as infrastructure.
The top two layers in the application networks deal with business logic and processes respectively. IMHO, these are the easiest of the layers to build as they are the most application specific.