The last few weeks I've been reading up on the Enterprise Service Bus (ESB). I can tell you: it was an amazing journey. I started out with the book by David Chappell and from then on went to IBM DeveloperWorks which is usually a good spot to get technical info. These two sources combined give a nice overview of what an ESB could offer you, and how to put it to use.
That was not enough. I needed more information, especially on what an ESB really is and how to fit it into our architecture. So I looked at a couple of Blogs around the ESB and the Mediation patterns. What surprised me was the number of discussions and especially the tone of them. It seems the whole ESB discussion has degraded to a kind of mudslinging between different fundamental groups. One group states that the ESB is an architectural monstrosity which is not needed whenever the initial design of the service constructs adhere to standards of good design. The other group argues that there will never be such an environment. Oh btw, both groups think they hold the truth, the whole truth and nothing but the truth. Well, what else is new?
I think I understand where this argument is coming from. Just have a look at the ESBs that vendors today deliver. Probably the only thing they have in common is the name and the fact that it can do some routing and transformation. There the resemblance ends. In short, there's no clear definition of what an ESB is or does.
If I look at the architectural concepts that I found during my search, especially mediation, integration and security, there's a lot to be said about using these patterns. If you can find a tool (whether or not it is called an ESB) that fits your needs now and in the near future, why not use it?
So in my opinion, there's definitely a case to be made about an 'ESB'. Just don't know yet exactly what should be in there and what not .....