SOAP - SOAPAction

What is SOAPAction?

  • SOAPAction is an HTTP header used in SOAP 1.1 requests.

  • It tells the server which operation (method) you want to call inside the web service.

  • Without it, the server might not know which method to execute, especially if multiple operations exist in the same service.

Format

SOAPAction: "namespace/MethodName"

  • It usually matches the operation’s namespace and name defined in the WSDL.

  • Example: "http://example.com/hello/SayHello"

Example Request with SOAPAction

HTTP Headers

POST /hello.asmx HTTP/1.1
Host: example.com
Content-Type: text/xml; charset=utf-8
Content-Length: 300
SOAPAction: "http://example.com/hello/SayHello"

SOAP Body

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"
               xmlns:tns="http://example.com/hello">
  <soap:Body>
    <tns:SayHello>
      <tns:name>John</tns:name>
    </tns:SayHello>
  </soap:Body>
</soap:Envelope>

SOAPAction in SOAP Versions

  • SOAP 1.1 → Requires the SOAPAction HTTP header.

  • SOAP 1.2 → Uses a different header (Content-Type with action parameter). Example:

    Content-Type: application/soap+xml; charset=utf-8; action="http://example.com/hello/SayHello"

In C# / .NET

  • If you generate a client proxy (via Add Service Reference), .NET automatically includes the correct SOAPAction in the HTTP headers.

  • If you make manual calls (using HttpClient), you must set the header yourself:

content.Headers.Add("SOAPAction", "http://example.com/hello/SayHello");

 In short:
SOAPAction is like a “method selector” — it tells the server exactly which operation you want to invoke in a SOAP service.