Apache Camel ™ is a versatile open-source integration framework (with powerful Bean Integration) based on known Enterprise Integration Patterns.
Camel empowers you to define routing and mediation rules in a variety of domain-specific languages, including a Java-based Fluent API, Spring or Blueprint XML Configuration files, and a Scala DSL. This means you get smart completion of routing rules in your IDE, whether in a Java, Scala or XML editor.
Apache Camel uses URIs to work directly with any kind of Transport or messaging model such as HTTP, ActiveMQ, JMS, JBI, SCA, MINA or CXF, as well as pluggable Components and Data Format options. Apache Camel is a small library with minimal dependencies for easy embedding in any Java application. Apache Camel lets you work with the same API regardless which kind of Transport is used - so learn the API once and you can interact with all the Components provided out-of-box.
Apache Camel has powerful Bean Binding and seamless integration with popular frameworks such as Spring, Blueprint and Guice. Camel also has extensive support for unit testing your routes.
Camel is one of the best lightweight integration frameworks fo Java. It requires some time to learn how to develop routes, handle errors and so on, but with some experience you can write almost any integration pattern in just few lines of code. Other disadvantages include: some api breaking changes between versions and lack of persistence layer in few pattern implementations. You can use Camel in any Java app server, but SMX4 seems to be most integrated. Generally - great framework!
Super simple, yet powerfull. This kind of software we need.