I noticed while I was browsing the WSDL spec was about specifying the message transmission. From http://www.w3.org/TR/wsdl#_porttypes ---------------------------------------------------------- WSDL has four transmission primitives that an endpoint can support:
One-way. The endpoint receives a message. Request-response. The endpoint receives a message, and sends a correlated message. Solicit-response. The endpoint sends a message, and receives a correlated message. Notification. The endpoint sends a message. ---------------------------------------------------------- Our normal RPC calls are request-response. I have a system that requires callbacks which fit the solicit-response model. Reading further at http://www.w3.org/TR/wsdl#_solicit-response ---------------------------------------------------------- Note that a solicit-response operation is an abstract notion; a particular binding must be consulted to determine how the messages are actually sent: within a single communication (such as a HTTP request/response), or as two independent communications (such as two HTTP requests). ---------------------------------------------------------- My preference is the two-HTTP-request method, so I don't have to implement a lightweight HTTP servlet engine in the client. Since there is no declaration of the transmission method in WSDL (yet?), it is obviously up to the Web Service engine to decide the implementation for a port binding. I do not know whether SOAP/HTTP engines implement all four transmission primitives or not, but I'm curious if they do and how they would actually recommend servicing a callback solicit-response method. cheers, Simon
