WCF event processing

In recent work, the host program needs to receive service feedback after loading the WCF Service.

Q: After the host is started, it is separated from the service. How can I get service feedback in a timely manner? If it is in winform, we can directly obtain it through the event, which is different from the implementation of WCF.

Processing Method:

Use WCF to subscribe to/publish a service message to a subscriber

Code:

Reference: WCF Event Events, oreilly.programming.wcf.services.3rd.edition.aug.2010.pdf

Contract

using System;

using System.ServiceModel;

namespace ConsoleServer

{

    [ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(IWriteLogCallback))]

    public interface ILogService 

    {

        [OperationContract(IsInitiating = true, IsTerminating = false)]  

        void Write(string logMsg); 

        [OperationContract(IsInitiating = true, IsTerminating = false)]

        void RegisterListener();  

        [OperationContract(IsInitiating = false, IsTerminating = false)]

        void UnregisterListener();

    }

    [ServiceContract]

    public interface IWriteLogCallback

    {

        [OperationContract(IsOneWay = true)]  

        void OnWriteLog(string logMsg);  } 

}

 

Service

using System;

using System.Diagnostics;

using System.ServiceModel;

using System.Collections.Generic;

namespace ConsoleServer

{

    [ServiceBehavior(IncludeExceptionDetailInFaults = true, InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)]  

    public class LogService:ILogService

    {

        Dictionary<string, OperationContext> listeners = new Dictionary<string, OperationContext>();

        public LogService() 

        {

            Trace.WriteLine("Create LogService Instance.");  

        }

        private void BroadCast(string logMsg)  

        {  

            List<string> errorClints = new List<string>();  

            foreach (KeyValuePair<string, OperationContext> listener in listeners)

            { 

                try  

                {  

                    listener.Value.GetCallbackChannel<IWriteLogCallback>().OnWriteLog(logMsg);  

                } 

                catch (System.Exception e) 

                {  

                    errorClints.Add(listener.Key);  

                    Trace.WriteLine("BROAD EVENT ERROR:" + e.Message);  

                }  

            }  

            foreach (string id in errorClints) 

            {  

                listeners.Remove(id); 

            }  

        }  

# Region ilogservice Member

        public void Write(string logMsg)  

        { 

            Trace.WriteLine("Write LOG:"+logMsg); 

            BroadCast(logMsg);  

        }  

        public void RegisterListener()

        {  

            listeners.Add(OperationContext.Current.SessionId, OperationContext.Current);  

            Trace.WriteLine("SessionID:" + OperationContext.Current.SessionId);

            Trace.WriteLine("Register listener. Client Count:" + listeners.Count.ToString()); 

        }  

        public void UnregisterListener() 

        {  

            listeners.Remove(OperationContext.Current.SessionId); 

            Trace.WriteLine("SessionID:" + OperationContext.Current.SessionId);

            Trace.WriteLine("Unregister listener. Client Count:" + listeners.Count.ToString());  

        }  

        #endregion 

    }

}

Call

using System;

using System.ServiceModel;

namespace ConsoleServer

{

    class Program

    {

        static void Main(string[] args)

        {

            try

            {

                using (ServiceHost host = new ServiceHost(typeof(LogService)))

                {

                    host.AddServiceEndpoint(typeof(ILogService), new NetNamedPipeBinding(),

                        "net.pipe://localhost/LogService");

                    host.Opened += (sender, e) =>

                    {

                        Console.WriteLine("service is start");

                        LogClient client = new LogClient();

                        ILogService service = DuplexChannelFactory<ILogService>.CreateChannel

                            (client, new NetNamedPipeBinding(), 

                            new EndpointAddress("net.pipe://localhost/LogService"));

                        service.RegisterListener();

                        service.Write("client start");

                        Console.ForegroundColor = ConsoleColor.White;

                        Console.WriteLine("press any key exits");

                        Console.ReadLine();

                        service.UnregisterListener();

                    };

                    host.Open();

                }

            }

            catch (Exception ex)

            {

                Console.WriteLine(ex.Message);

            }

            Console.ReadLine();

        }

    }

    public class LogClient : IWriteLogCallback

    {

        #region IWriteLogCallback Members

        public void OnWriteLog(string logMsg)

        {

            Console.ForegroundColor = ConsoleColor.Green;

            Console.WriteLine(logMsg);

        }

        #endregion

    }

}