The little series I am currently writing here on my blog has inspired me to write way too more code than actually necessary to get my point across ;-) So by now I've got my own MSMQ transport for WSE 2.0 (yes, I know that others have written that already, but I am shooting for a "enterprise strength" implementation), a WebRequest/WebResponse pair to smuggle under arbitrary ASMX proxies and I am more than halfway done with a server-side host for MSMQ-to-ASMX (spelled out: ASP.NET Web Services).
What bugs me is that WSE 2.0's messaging model is "asynchronous only" and that it always performs a push/pull translation and that there is no way to push a message through to a service on the receiving thread. Whenever I grab a message from the queue and put it into my SoapTransport's "Dispatch()" method, the message gets queued up in an in-memory queue and that is then, on a concurrent thread, pulled (OnReceiveComplete) by the SoapReceivers collection and submitted into ProcessMessage() of the SoapReceiver (like any SoapService derived implementation) matching the target endpoint. So while I can dequeue from MSMQ within a transaction scope (ServiceDomain), that transaction scope doesn't make it across onto the thread that will actually execute the action inside the SoapReceiver/SoapService.
So now I am sitting here, contemplating and trying to figure out a workaround that doesn't require me to rewrite a big chunk of WSE 2.0 (which I am totally not shy of if that is what it takes). Transaction marshaling, thread synchronization, ah, I love puzzles. Once I am know how to solve this and have made the adjustments, I'll post the queue listener I promised to wrap up the series. The other code I've written in the process will likely surface in some other way.