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As I understand it, the best way to post some useful info you've learned is to ask the question yourself and then answer it, so here goes.

The scenario:

  • we have an app that contructs a SOAP request from a template xslt file and subs in a few parameters, including the MessageID
  • the real service it accesses like the requests, responds happily and our client processes the response happily
  • we're trying to build a stub/responder that simulates the service
  • stub just implements IHttpHandler and responds to any POST operation
  • stub reads a canned response, which is an example of a real response, from an XML file and sends it over the wire
  • both Visual Round Trip Analyzer (NetMon under the hood) and Fiddler see the response travelling over the wire to the client
  • SendRequestResponse eventually times out and throws an exception
James McLachlan
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1 Answers1

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SoapClient.SendRequestResponse is aware of the MessageID in the outgoing request SOAP header and won't complete the call until it receives a message with a RelatesTo value that matches the original MessageID. So if you're crafting a responder/stub you much parse out the MessageID from the request and inject it into the RelatesTo field in the SOAP header of the response.

It's a little odd that it doesn't just return after any valid SOAP message and throw an expection because of the mismatch. Perhaps this is part of the SOAP web services standard. I didn't look into it.

Example:

Request:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance/" xmlns:xsd="http://www.w3.org/2001/XMLSchema/" xmlns:wsa="http://schemas.xmlsoap.org/ws/2004/03/addressing" xmlns:wsu="http://schemas.xmlsoap.org/ws/2002/07/utility">
  <soap:Header>
    <wsa:MessageID soap:mustUnderstand="1">uuid:20E6C5D8-2E0D-48D0-863D-7789D2CA37A2</wsa:MessageID>
...

Response:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:wsa="http://schemas.xmlsoap.org/ws/2004/03/addressing" xmlns:wsu="http://schemas.xmlsoap.org/ws/2002/07/utility">
  <soap:Header>
    <wsa:MessageID SOAP-ENV:mustUnderstand="1" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">uuid:bb1cf43050739c45:248138d0:1328e31d4e2:-5cf4</wsa:MessageID>
    <wsa:RelatesTo RelationshipType="wsa:Reply" SOAP-ENV:mustUnderstand="1" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">uuid:20E6C5D8-2E0D-48D0-863D-7789D2CA37A2</wsa:RelatesTo>
...

The RelatesTo value is the same as the MessageID value in the request. The MessageID in the response is new and unique because the response message is not the request message.

James McLachlan
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