Proteus is a toolkit for message-based Enterprise Application Integration. It includes adapters that allow databases, message queues, FTP servers, email, and other message sources and sinks to be addressed in a simple, uniform fashion. It also includes a simple but very capable message broker. The broker allows routing and transformation of messages from and to all the sources and sinks for which adapters exist. Transformations may be custom-written in Java or XSLT (the broker uses Xalan as its XSLT transformation engine).
The current (0.1) release is not yet feature-complete, but is useful for certain limited production applications.