Open Source SOA has arrived! On a single day we have one platform announce that they have simplified basic SOA, and another has announced that SOA is never simple - and if it is simple, just use web services. The question is... is there really a simple SOA and a not-so-simple SOA?
As I look at it, there is a very fine line between simple SOA and the more complex ones that require an enterprise service bus (ESB). Lines are blurred today. Now, ESB itself can be in a single container or more massively distributed ESBs with a strong messaging backbone (like Sonic ESB). But messaging backbone or not is more about the underlying integration infrastructure. So, what does it mean for the application itself? Is the model/paradigm different for the two cases? This is what gets lost out in the melee - the application models and the underlying infrastructure are quite decoupled. From an application standpoint many of the ESB mediation requirements may always be needed functionally. Can one access services without getting the data in the right format? To get it in the right format, won't we need data transformation? And security is a given in all cases. Sometimes one can look at business rules based routing to services. All of these regardless of whether it is a simple SOA or not-so-simple (more distributed multi-data-center) SOA.
This (common treatment of all SOA use cases regardless of complexity) is very evident with the way our open source platform, FUSE, works because it has an embeddable transport layer. One could use the containers with or without Active MQ. But with or without distribution, the same functionality is available. Simple SOA? Or not?