ActiveSOAP is a lightweight & easily embeddable REST and SOAP stack based on StAX with support for WS-Addressing and WSIF.
ActiveSOAP uses StAX (the Standard API for pull parsing) to implement the SOAP protocols and then it delegates to plugin Handler objects for the heavy duty processing of the XML payloads. This means that you only need to pay for what you need; use fast pull based event parsing or full data binding mechanisms like JAXB or XStream or DOMish APIs like XMLBeans when they make sense.
You can use whatever XML marshalling and/or parsing tool you like to process different messages or headers. The following APIs are currently supported
ActiveSOAP is currently used to provide WS-Notification support in ServiceMix.
In addition to the core StAX processing of SOAP requests (client and server side) ActiveSOAP provides support for WS-Addressing and provides multiple WSIF providers.
To get a feel for how you can work with document centric web services using ActiveSOAP and XMLBeans, take a look at an Example.
There is also a dynamic client invocation API which you can use if you don't want to generate interfaces from your WSDLs such as in this example
To get a feel for the architecture, try reading How it works