New Impala extensions project

I've created a new Impala Extensions project, also on Google Code. The idea is to host modules, typically extensions to Spring or Impala or both, which are generically useful, but not substantial enough to warrant their own project and too far from the core of Impala to warrant inclusion in Impala itself.

So far the extensions project contains a set of extensions to Spring annotation-based MVC framework, and also a general purpose event management framework, particularly useful for managing persistent and asynchronous events (as a lightweight alternative to JMS). I expect the list to into a number of other areas over time.

The extensions project also contains an example application which can be used as testbed for individual modules.