title: Problem with WCF client calling one-way operation
body: <p>I have run into a problem when calling web service on a SAP PI bus from my WCF client.
  The operation is defined as one-way, and the method on my proxy operation contract is decorated accordingly when the service reference is added.
  However, the service client gets an exception when calling the according operation: </p>
  
  <p><strong><em>The one-way operation returned a non-null message with Action=''</em></strong></p>
  
  <p>Using SoapUI, the method on the bus can be called successfully, and it returns a SOAP envelope with an empty body. The bus people told me, this is according to the SOAP specs:</p>
  
  <hr>
  
  <p>(SOAP specs, chapter 4.7.9, One-way operations):</p>
  
  <p>There are differing interpretations of how HTTP is to be used when performing one-way operations. </p>
  
  <p><strong>R2714</strong> For one-way operations, an INSTANCE MUST NOT return a HTTP response that contains an envelope. Specifically, the HTTP response entity-body must be empty. </p>
  
  <p><strong>R2750</strong> A CONSUMER MUST ignore an envelope carried in a HTTP response message in a one-way operation. </p>
  
  <p><strong>R2727</strong> For one-way operations, a CONSUMER MUST NOT interpret a successful HTTP response status code (i.e., 2xx) to mean the message is valid or that the receiver would process it. </p>
  
  <hr>
  
  <p>So it seems, my WCF client doesn't comply with R2750.</p>
  
  <p>I have found out that when I force the operation contract on the proxy to be <em>IsOneWay = false</em>, everything works.</p>
  
  <p>Is there anything wrong with the way WCF handles one way operations or do I do something wrong (more likely)? 
  Is there anything else I should do, it just doesn't seem right to override the generated WCF proxy client.</p>
  
  <p>Thanks for any suggestions.</p>