After working with IBM Datapower; I googled around to see if there was an open source mediation alternative. I had thought I found a topic which was not covered by open source projects and I would start it immediately.But I was wrong; there was already a nice one by Apache. Although Synapse is not an %100 alternative to Datapower, it is a nice mediation project.
Immediatelly I thought I still had chance to improve it with config editors, management, monitoring etc. Again it was already implemented by another project: wso2.
Wso2 includes Synapse and add features on top of it.
I recommend you to check these projects if you have not already. Just keep them in your mind that such projects exists; you may need them in future.
Now I am bit regret to implement my previous mediation project with Spring Integration. I could make use of these.