Enabling SOAP Message Inspection for a Single Operation - wcf

Question

How can I force an IMessageInspector to fire only when a specific operation is called, rather than firing whenever a call to the service is made? Currently, I am applying a custom IEndpointBehavior to the endpoint which calls this IMessageInspector, but this is not exactly what I would like to do...

Answer 1

The message inspectors are bound to the dispatch runtime object, which is a single one for each endpoint, not operation. If a parameter inspector works, then you can use it (it's bound to the operation), but if you need a message inspector, then it cannot be bound to a single operation. But you can, inside your inspector, check whether the operation is what you expect (based on the Action header, which is unique per operation), as shown in the code below.
public class StackOverflow_7502134
{
[ServiceContract]
public interface ITest
{
[OperationContract]
string Echo(string text);
[OperationContract]
int Add(int x, int y);
}
public class Service : ITest
{
public string Echo(string text)
{
return text;
}
public int Add(int x, int y)
{
return x + y;
}
}
public class MyInspector : IEndpointBehavior, IDispatchMessageInspector
{
string[] operationNames;
public MyInspector(params string[] operationNames)
{
this.operationNames = operationNames ?? new string[0];
}
public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
{
}
public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
{
}
public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
{
endpointDispatcher.DispatchRuntime.MessageInspectors.Add(this);
}
public void Validate(ServiceEndpoint endpoint)
{
}
public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
{
// by default, action == <serviceContractNamespace>/<serviceContractName>/<operationName>
string operationName = request.Headers.Action.Substring(request.Headers.Action.LastIndexOf('/') + 1);
if (this.operationNames.Contains(operationName))
{
Console.WriteLine("Inspecting request to operation {0}", operationName);
Console.WriteLine(request);
Console.WriteLine();
return operationName;
}
else
{
return null;
}
}
public void BeforeSendReply(ref Message reply, object correlationState)
{
string operationName = correlationState as string;
if (operationName != null)
{
Console.WriteLine("Inspecting reply from operation {0}", operationName);
Console.WriteLine(reply);
Console.WriteLine();
}
}
}
public static void Test()
{
string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
MyInspector inspector = new MyInspector("Add"); // inspecting Add, not Echo
host.AddServiceEndpoint(typeof(ITest), new BasicHttpBinding(), "").Behaviors.Add(inspector);
host.Open();
Console.WriteLine("Host opened");
ChannelFactory<ITest> factory = new ChannelFactory<ITest>(new BasicHttpBinding(), new EndpointAddress(baseAddress));
ITest proxy = factory.CreateChannel();
Console.WriteLine("Calling Echo");
Console.WriteLine(proxy.Echo("Hello world"));
Console.WriteLine();
Console.WriteLine("Calling Add");
Console.WriteLine(proxy.Add(4, 5));
((IClientChannel)proxy).Close();
factory.Close();
Console.Write("Press ENTER to close the host");
Console.ReadLine();
host.Close();
}
}