I have a problem with a 3rd party application and my WCF web service that always returns a HTTP 400 ("bad request") error when connecting with the 3rd party application. The WebService is implemented via .NET, runs on MS Windows Server 2012-R2 and IIS8 and exposes an interoperable WSDL interface to connect to. The service itself is working pretty fine. I think the problem is more server- than service-related.
The WebService uses MTOM message encoding because of large result sets and on HTTP level this is realized via multipart HTTP messages. Basically the client send the headers first with a "Expect: 100-continue" field and an indentifier, the server acknowledges and then the client sends the rest. When using WCFTestClient from Microsoft, everythings works fine.
The developer of the 3rd party app says his app sends header and body at the same time which may cause the server to respond with a bad request.
He suggested to configure the server to accept header and body at the same time. I spent some time searching but I think I might have problems to describe the problem in short words. I have no idea where to find such a setting. Does anyone know more about this situation?
