How to use IDispatchMessageInspector in a WCF Service?

Question

I am trying to use IDispatchMessageInspector in a WCF service implementation to access custom header values.

Something like:

public class MyService :         


        

Answer 1

I'm using IClientMessageInspector for same goal. Here is how you can apply them from code:

 var serviceClient = new ServiceClientClass(binding, endpointAddress);
serviceClient.Endpoint.Behaviors.Add(
            new MessageInspectorEndpointBehavior());


/// 

/// Represents a run-time behavior extension for a client endpoint.
/// 
public class MessageInspectorEndpointBehavior : IEndpointBehavior
    where T: IClientMessageInspector, new()
{
    /// 

    /// Implements a modification or extension of the client across an endpoint.
    /// 
    /// The endpoint that is to be customized.
    /// The client runtime to be customized.
    public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
    {
        clientRuntime.MessageInspectors.Add(new T());
    }

    /// 

    /// Implement to pass data at runtime to bindings to support custom behavior.
    /// 
    /// The endpoint to modify.
    /// The objects that binding elements require to support the behavior.
    public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
    {
        // Nothing special here
    }

    /// 

    /// Implements a modification or extension of the service across an endpoint.
    /// 
    /// The endpoint that exposes the contract.
    /// The endpoint dispatcher to be modified or extended.
    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
    {
        // Nothing special here
    }

    /// 

    /// Implement to confirm that the endpoint meets some intended criteria.
    /// 
    /// The endpoint to validate.
    public void Validate(ServiceEndpoint endpoint)
    {
        // Nothing special here
    }
}

And here is sample implementation of MessageInspector I'm using to pass client version to server, and retrieve server version in custom headers:

/// 

/// Represents a message inspector object that can be added to the MessageInspectors collection to view or modify messages.
/// 
public class VersionCheckMessageInspector : IClientMessageInspector
{
    /// 

    /// Enables inspection or modification of a message before a request message is sent to a service.
    /// 
    /// The message to be sent to the service.
    /// The WCF client object channel.
    /// 
    /// The object that is returned as the  argument of
    /// the  method.
    /// This is null if no correlation state is used.The best practice is to make this a  to ensure that no two
    ///  objects are the same.
    /// 
    public object BeforeSendRequest(ref Message request, IClientChannel channel)
    {
        request.Headers.Add(new VersionMessageHeader());
        return null;
    }

    /// 

    /// Enables inspection or modification of a message after a reply message is received but prior to passing it back to the client application.
    /// 
    /// The message to be transformed into types and handed back to the client application.
    /// Correlation state data.
    public void AfterReceiveReply(ref Message reply, object correlationState)
    {
        var serverVersion = string.Empty;
        var idx = reply.Headers.FindHeader(VersionMessageHeader.HeaderName, VersionMessageHeader.HeaderNamespace);
        if (idx >= 0)
        {
            var versionReader = reply.Headers.GetReaderAtHeader(idx);
            while (versionReader.Name != "ServerVersion"
                   && versionReader.Read())
            {
                serverVersion = versionReader.ReadInnerXml();
                break;
            }
        }

        ValidateServerVersion(serverVersion);
    }

    private static void ValidateServerVersion(string serverVersion)
    {
        // TODO...
    }
}

public class VersionMessageHeader : MessageHeader
{
    public const string HeaderName = "VersionSoapHeader";
    public const string HeaderNamespace = "";
    private const string VersionElementName = "ClientVersion";

    public override string Name
    {
        get { return HeaderName; }
    }

    public override string Namespace
    {
        get { return HeaderNamespace; }
    }

    protected override void OnWriteHeaderContents(XmlDictionaryWriter writer, MessageVersion messageVersion)
    {
        writer.WriteElementString(
            VersionElementName,
            Assembly.GetExecutingAssembly().GetName().Version.ToString());
    }
}