A tutorial, the
XINS Calling Convention Primer is now available, that shows how to extend XINS with your own communication protocols.
Out of the box XINS already supports SOAP, XML-RPC, XSLT and a simple browser-compatible protocol.
Writing your own calling convention allows you to add support for a specific protocol, such as
REST, a SOAP variant,
JSON-RPC or
Hessian. The only requirement is that the protocol is HTTP-based.
Do you consider protocol-independence a unique selling point of a web framework?