Question

Got an error while trying to invoke the webservice

“System.NullReferenceException: Object reference not set to an instance of an object.”
Error on this line

if (Authentication.Username == "x" &&
            Authentication.Password == "y")

what does this mean?

---

[WebService(Namespace = "https://domain.com")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]
public class Testing : System.Web.Services.WebService
{
    public TestAuthHeader Authentication;
    public class TestAuthHeader : SoapHeader
    {
        public string Username;
        public string Password;
    }

    [WebMethod]
    [SoapHeader("Authentication")]
    public string TestService()
    {
        if (Authentication.Username == "x" &&
            Authentication.Password == "y")
        {
            return "OK";
        }
        else
        {
            return "Access Denided";
        }
    }
}

Answer 1

Try moving the definition of class TestAuthHeader outside of the web service itself…

Also, try testing unknown headers to see if Authentication is ending up there…

[WebMethod]
[SoapHeader("Authentication")]
[SoapHeader("unknownHeaders",Required=false)]
public string TestService()
{
   foreach (SoapUnknownHeader header in unknownHeaders) {
      // Test header
      Debug.Write(header.Element.Name);
   }
}

Other than that, can we see the code where you’re calling into the web service?

*Edit *

If you’re not doing anything on the client side to create an instance of TestAuthHeader and set its properties, you’re going to have a null reference on the service side. From the MSDN example of using SoapHeaders (client code):

MyHeader mySoapHeader = new MyHeader();

// Populate the values of the SOAP header.
mySoapHeader.Username = Username;
mySoapHeader.Password = SecurelyStoredPassword;

// Create a new instance of the proxy class.
MyWebService proxy = new MyWebService();

// Add the MyHeader SOAP header to the SOAP request.
proxy.MyHeaderValue = mySoapHeader;

// Call the method on the proxy class that communicates with
// your Web service method.
string results = proxy.MyWebMethod();

All you really need is:

public string TestService()
{
    if (Authentication == null) {
        return "Access is denied";
    }

    // ... the rest of your code

This will handle the scenario of where the client doesn’t set an authentication object.