Syncing correlationstate between IClientMessageInspector and IParameterInspector

Question

I have a wcf client. According to requirements, I need to record some of the metadata in the request (as well as user data which is not included in the request.) Then, if the request is successful I may have to record response metadata and depending on flags, the full soap request.

I am trying to do this the right way (using IParameterInspector to examine the metadata and IClientMessageInspector to get the Soap), but I have no way of correlating the two Interface requests. I am not sure about thread safety here. This is a stripped down version of where I am at...

     public class SoapRequestInfo
{
    public string UserId { get; set; }
    public Guid Key { get; set; }
    //would contain a lot more info
}

public class OperationProfilerParameterInspector : IParameterInspector, IClientMessageInspector
{
    //before serialization
    public object BeforeCall(string operationName, object[] inputs) //IParameterInspector
    {
        //Add the operation, record some specific inputs to db
        return new SoapRequestInfo
                            {
                                UserId = "1234",
                                Key = new Guid()
                            };
    }

    public void AfterCall(string operationName, object[] outputs, object returnValue, object correlationState) //IParameterInspector
    {
       var info = correlationState as SoapRequestInfo;
        //Do some additional logging - easy enough
    }

    public object BeforeSendRequest(ref Message request, IClientChannel channel) //IClientMessageInspector
    {
        //want to correlate this with IParameterInspector
        return null;
    }


    public void AfterReceiveReply(ref Message reply, object correlationState) //IClientMessageInspector
    {
        //May want to log full soap message depending on after call criteria
    }
}      

I know I can't use a private variable to hold the Guid. I can't use session, because there can be multiple requests in close succession and can't guarantee the response is correct. So how can I uniquely identify the correlationState between the two interfaces?

Answer 1

You can probably use HttpContext.Items to keep your object if your service is running in ASPNET compatibility mode otherwise you can use TLS (Thread Local Storage), put the data in a slot and fetch/clear later.