Question

We have multiple WCF services all working with InstanceContextMode=PerCall and all WCF service instances are generated by employing Unity (IOC) and implementing IInstanceProvider.

A correlation identifier is used to audit all method calls and database processes with the same identifier.

In order to achieve this, an endpoint behavior is created by implementing IDispatchBehavior and in AfterReceiveRequest method, a guid is generated and assigned to a ThreadStatic (CommonData) property. This property can be access in all layers of the application. The following code block shows the population of CommonData, and the CommonData class;

public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
        {
            CommonData.ClearDictionary();
            //the lines between are deleted as they are not relevant to the question

            CommonData.Current.Add(MessageHeaderCodes.CorrelationId, Guid.NewGuid().ToString());    
            return null;
        }

and commondata class:

public class CommonData
    {            
        [ThreadStatic]
        private static Dictionary<string, string> headerData;    

        public static Dictionary<string, string> Current
        {
            get
            {
                if (headerData == null)
                {
                    headerData = new Dictionary<string, string>();
                }
                return headerData;
            }            
        }

        private CommonData()
        {

        }

        public static string GetHeader(string header)
        {
            string headerValue = string.Empty;
            KeyValuePair<string, string> headerKeyValuePair = CommonData.Current.SingleOrDefault(p => p.Key == header);
            headerValue = headerKeyValuePair.Value;
            return headerValue;
        }

        public static void ClearDictionary()
        {
            Current.Clear();
        }
    }

The problem here is the following;
In some of the services, developers reported that the correlation identifier returns null. Since the problem is intermittant it is not possible to have a full stack trace at the moment. Also, they stated that reseting IIS resolves this problem temporarily.

Any help is appreciated…

Answer 1

As Blam suggested, I have employed OperationContext.Current by writing an Extension to store custom objects. Below is the extension:

public class OperationContextExtension : IExtension<OperationContext>
{
    public void Attach(OperationContext owner)
    {
        this.Current = new Dictionary<string, string>();
    }

    public void Detach(OperationContext owner)
    {
        this.Current = null;
    }

    public Dictionary<string,string> Current { get; set; }
}

On the otherhand, I have to add System.ServiceModel reference to the domain objects. Although it does not seem to be a proper way as domain objects can access to the service layer, it resolved my problem.