The Synapse project is a robust, lightweight implementation of a highly scalable and distributed service mediation framework based on Web services and XML specifications.
Project Open ESB implements an Enterprise Service Bus (ESB) runtime using Java Business Integration as the foundation. This allows easy integration of web services to create loosely coupled enterprise class composite applications.
Codehaus XFire is a next-generation java SOAP framework. Codehaus XFire makes service oriented development approachable through its easy to use API and support for standards. It is also highly performant since it is built on a low memory StAX based model.