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?