WCF Duplex：将回调发送到特定订阅的ASP.NET Webforms客户端

Question

I'm working on an ASP.NET 4.0 Webforms client application that connects to a WCF 4.0 Duplex service to realize some kind of flat file processing. When an user enters to a page on the Page_Load event I subscribe the client to the duplex service, this is because I need to notify all clients under some circumstances:

A) The client that started the process must be notified when the process starts.

B) The client that started the process must be notified when a file is processed.

C) The client that started the process must be notified when the whole process finished.

D) If a new client (subscriber) enters when the process already started, must receive a specific notification.

E) If there are more than one client (subscriber) active when one of them starts the process, the others must receive a specific notification.

I already have this logic written but I'm having a lot of issues trying to accomplish the specific subscriber notification, it seems like to WCF all clients/instances of the web application are recognized as the same, I'm receiving all notifications in the client that started the process, if I open other browsers and start new sessions (on ASP.NET) I receive the same notifications, nothing specific.

Here you can see a reduced version of my code

WCF Service Interfaces

using System.ServiceModel;

namespace WcfService
{
    [ServiceContract(CallbackContract = typeof(IService1DuplexCallback))]
    public interface IService1
    {
        [OperationContract(IsOneWay = true)]
        void Subscribe(string idSesion);

        [OperationContract(IsOneWay = true)]
        void ProcessFiles(string idSesion);
    }

    public interface IService1DuplexCallback
    {
        [OperationContract(IsOneWay = true)]
        void NotifyProcessWorking();

        [OperationContract(IsOneWay = true)]
        void NotifyProcessStarted();

        [OperationContract(IsOneWay = true)]
        void NotifyFileProcessed(int id);

        [OperationContract(IsOneWay = true)]
        void NotifyProcessFinished();
    }
}

WCF Service Implementation

using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Threading;
using System.Threading.Tasks;

namespace WcfService
{
    [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)]
    public class Service1 : IService1
    {
        private static List<KeyValuePair<string, IService1DuplexCallback>> _clients = new List<KeyValuePair<string, IService1DuplexCallback>>();
        private static bool _isProcessStarted;
        private static string _sessionStarted = string.Empty;

        public void Subscribe(string idSesion)
        {
            lock (_clients)
            {
                if (!_clients.Any(x => string.Equals(x.Key, idSesion, StringComparison.InvariantCultureIgnoreCase)))
                {
                    var callback = OperationContext.Current.GetCallbackChannel<IService1DuplexCallback>();

                    if (callback != null)
                    {
                        var currentSubscriber = new KeyValuePair<string, IService1DuplexCallback>(idSesion, callback);
                        _clients.Add(currentSubscriber);
                    }
                }
            }

            if (_isProcessStarted)
            {
                NotifyProcessWorking(idSesion);
            }
        }

        public void ProcessFiles(string idSesion)
        {
            _isProcessStarted = true;
            _sessionStarted = idSesion;

            try
            {
                var mockFileCount = 23;
                var r = new Random();

                NotifyStarted();
                NotifyProcessWorking();

                Parallel.For(0, mockFileCount, (i) =>
                {
                    //Do a lot of specific validations... (time betweeen 5 secs and 2 minutes per file)
                    var time = r.Next(5000, 120000);

                    Thread.Sleep(time);

                    NotifyFileProcessed(i);
                });

                NotifyProcessFinished();
            }
            catch (Exception ex)
            {
                throw;
            }

            _isProcessStarted = false;
        }

        private static void NotifyStarted()
        {
            var c = _clients.FirstOrDefault(x => string.Equals(x.Key, _sessionStarted, StringComparison.InvariantCultureIgnoreCase));

            try
            {
                c.Value.NotifyProcessStarted();
            }
            catch (Exception ex)
            {
                lock (_clients)
                {
                    _clients.Remove(c);
                }
            }
        }

        private static void NotifyFileProcessed(int idFile)
        {
            var c = _clients.FirstOrDefault(x => string.Equals(x.Key, _sessionStarted, StringComparison.InvariantCultureIgnoreCase));

            try
            {
                c.Value.NotifyFileProcessed(idFile);
            }
            catch (Exception ex)
            {
                lock (_clients)
                {
                    _clients.Remove(c);
                }
            }
        }

        private static void NotifyProcessFinished()
        {
            foreach (var c in _clients)
            {
                try
                {
                    c.Value.NotifyProcessFinished();
                }
                catch (Exception ex)
                {
                    lock (_clients)
                    {
                        _clients.Remove(c);
                    }
                }
            }
        }

        private static void NotifyProcessWorking(string idSesion = "")
        {
            if (string.IsNullOrEmpty(idSesion))
            {
                foreach (var c in _clients)
                {
                    try
                    {
                        c.Value.NotifyProcessWorking();
                    }
                    catch (Exception ex)
                    {
                        lock (_clients)
                        {
                            _clients.Remove(c);
                        }
                    }
                }
            }
            else
            {
                var c = _clients.FirstOrDefault(x => string.Equals(x.Key, idSesion, StringComparison.InvariantCultureIgnoreCase));

                try
                {
                    c.Value.NotifyProcessWorking();
                }
                catch (Exception)
                {
                    lock (_clients)
                    {
                        _clients.Remove(c);
                    }
                }
            }
        }
    }
}

WCF Service Web.config

<?xml version="1.0"?>
<configuration>
  <appSettings/>
  <system.web>
    <compilation debug="true" targetFramework="4.0"/>
    <httpRuntime/>
  </system.web>
  <system.serviceModel>
    <services>
      <service name="WcfService.Service1">
        <endpoint address="" binding="wsDualHttpBinding" bindingConfiguration="FileProcessorDuplexBinding" 
                  name="FileProcessorDuplexEndPoint" contract="WcfService.IService1"/>
      </service>
    </services>
    <bindings>
      <wsDualHttpBinding>
        <binding name="FileProcessorDuplexBinding" closeTimeout="00:30:00" openTimeout="00:30:00" 
                 sendTimeout="00:30:00" receiveTimeout="00:30:00" maxBufferPoolSize="2147483647"
                 maxReceivedMessageSize="2147483647">
          <reliableSession inactivityTimeout="00:30:00"/>
          <readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" maxArrayLength="2147483647" 
                        maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647"/>
          <security mode="None"/>
        </binding>
      </wsDualHttpBinding>
    </bindings>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <serviceHostingEnvironment  multipleSiteBindingsEnabled="true"/>
  </system.serviceModel>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
    <directoryBrowse enabled="true"/>
  </system.webServer>
</configuration>

ASP.NET WebForm client UI

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="WebApplication.Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <script src="Scripts/jquery-2.1.4.min.js"></script>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>
            <asp:Button ID="btnStart" runat="server" Text="Start Process" OnClientClick="Start();"/>
            <br/>
            <br/>
            <asp:Label ID="lblStatus" runat="server" Text="[Process Status]"></asp:Label>
        </div>
        <script>

            function Start() {

                var loc = window.location.href;
                var dataValue = "{}";

                $.ajax({
                    type: "POST",
                    url: loc + "/StartProcess",
                    contentType: 'application/json',
                    data: dataValue,
                    dataType: 'json',
                    error: function(XMLHttpRequest, textStatus, errorThrown) {
                        alert("Request: " + XMLHttpRequest.toString() + "\n\nStatus: " + textStatus + "\n\nError: " + errorThrown);
                    },
                    success: function(result) {
                    }
                });

            }

            setInterval(function () {

                var loc = window.location.href;
                var dataValue = "{ id: '1' }";

                $.ajax({
                    type: "POST",
                    url: loc + "/CheckMessage",
                    contentType: 'application/json',
                    data: dataValue,
                    dataType: 'json',
                    error: function(XMLHttpRequest, textStatus, errorThrown) {
                        alert("Request: " + XMLHttpRequest.toString() + "\n\nStatus: " + textStatus + "\n\nError: " + errorThrown);
                    },
                    success: function(result) {
                        processMessage(result.d);
                    }
                });


            }, 1000);

            function processMessage(msg) {

                if (msg) {
                    switch (msg) {
                    case "working":
                        alert("Process currently working");
                        $('[id$=lblStatus]').attr('disabled', true);
                        break;

                    case "started":
                        $('#<%=lblStatus.ClientID%>').html("Process started");
                        break;

                    case "finished":
                        $('#<%=lblStatus.ClientID%>').html("Process finished");
                        break;

                    default:
                        var data = msg.split(":");
                        $('#<%=lblStatus.ClientID%>').html("File Processed: " + data[1]);
                        break;
                    }
                }
            }
        </script>
    </form>
</body>
</html>

ASP.NET WebForm client Code-Behind

using System;
using System.Collections.Concurrent;
using System.ServiceModel;
using System.Web.Services;
using System.Web.UI;
using WebApplication.ServiceReference1;

namespace WebApplication
{
    [CallbackBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, UseSynchronizationContext = false)]
    public partial class Default : Page, IService1Callback
    {
        private static ConcurrentQueue<string> _serviceReceivedMessages = new ConcurrentQueue<string>();
        private static string _sessionId = string.Empty;

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                _sessionId = Session.SessionID;

                var proxyDuplex = new Service1Client(new InstanceContext(new Default()));
                proxyDuplex.Subscribe(_sessionId);
            }
        }

        [WebMethod]
        public static void StartProcess()
        {
            var proxyDuplex = new Service1Client(new InstanceContext(new Default()));
            proxyDuplex.ProcessFiles(_sessionId);
        }

        [WebMethod]
        public static string CheckMessage(string id)
        {
            var message = string.Empty;

            _serviceReceivedMessages.TryDequeue(out message);

            return message ?? (message = string.Empty);
        }

        public void NotifyProcessWorking()
        {
            _serviceReceivedMessages.Enqueue("working");
        }

        public void NotifyProcessStarted()
        {
            _serviceReceivedMessages.Enqueue("started");
        }

        public void NotifyFileProcessed(int id)
        {
            _serviceReceivedMessages.Enqueue("processed:"+id);
        }

        public void NotifyProcessFinished()
        {
            _serviceReceivedMessages.Enqueue("finished");
        }
    }
}

ASP.NET WebForm client Web.config

<?xml version="1.0"?>
<configuration>
  <system.web>
    <compilation debug="true" targetFramework="4.0"/>
    <httpRuntime/>
  </system.web>
  <system.serviceModel>
    <bindings>
      <wsDualHttpBinding>
        <binding name="FileProcessorDuplexBinding" 
                 closeTimeout="00:30:00" openTimeout="00:30:00" receiveTimeout="00:30:00"
                 sendTimeout="00:30:00" maxBufferPoolSize="2147483647" maxReceivedMessageSize="2147483647"
                 clientBaseAddress="http://localhost:62778/TempUri">
          <reliableSession inactivityTimeout="00:30:00" />
          <readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647"
            maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647" />
          <security mode="None" />
        </binding>
      </wsDualHttpBinding>
    </bindings>
    <client>
      <endpoint address="http://localhost:62778/Service1.svc" binding="wsDualHttpBinding"
        bindingConfiguration="FileProcessorDuplexBinding" contract="ServiceReference1.IService1"
        name="FileProcessorDuplexEndPoint" />
    </client>
  </system.serviceModel>
</configuration>

Here you can download a Visual Studio 2015 solution with the whole code.

I would like to know what is wrong with my code, I think this behavior is possible but can not understand why WCF is not notifying the specific clients.

Thanks

Update 1

I made all changes @JuanK suggested me (at the time) with no luck, the behavior continues the same, I added a new console project to test the same service and in that project works fine

But in the ASP.NET project the error continues, the 2nd client gets all notifications

Here you can download the VS Solution updated (at this time)

Answer 1

WCF isn't notifying specific clients because you have coded that service must send notifications to everyone.

private static void NotifyProcessFinished()
{
    //FOR EACH CLIENT
    foreach (var c in _clients)
    {
        try
        {
            c.Value.NotifyProcessFinished();
        }
        catch (Exception ex)
        {
            lock (_clients)
            {
                _clients.Remove(c);
            }
        }
    }
}

On other hand there are some ServiceBehavior and static fields issues I have fixed here:

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class Service1 : IService1
{
    private static List<KeyValuePair<string, IService1DuplexCallback>> _clients = new List<KeyValuePair<string, IService1DuplexCallback>>();
    private static bool _isProcessStarted;
    private string _sessionStarted = string.Empty;

    public void Subscribe(string idSesion)
    {
        lock (_clients)
        {
            if (!_clients.Any(x => string.Equals(x.Key, idSesion, StringComparison.InvariantCultureIgnoreCase)))
            {
                var callback = OperationContext.Current.GetCallbackChannel<IService1DuplexCallback>();

                if (callback != null)
                {
                    var currentSubscriber = new KeyValuePair<string, IService1DuplexCallback>(idSesion, callback);
                    _clients.Add(currentSubscriber);
                }
            }
        }

        if (_isProcessStarted)
        {
            NotifyProcessWorking(idSesion);
        }
    }

    public void ProcessFiles(string idSesion)
    {
        _isProcessStarted = true;
        _sessionStarted = idSesion;

        try
        {
            var mockFileCount = 2;
            var r = new Random();

            NotifyStarted();
            NotifyProcessWorking();

            Parallel.For(0, mockFileCount, (i) =>
            {
                //Do a lot of specific validations... (time betweeen 5 secs and 2 minutes per file)
                var time = 5000;//r.Next(5000, 120000);

                Thread.Sleep(time);

                NotifyFileProcessed(i);
            });

            NotifyProcessFinished();
        }
        catch (Exception ex)
        {
            throw;
        }

        _isProcessStarted = false;
    }

    private void NotifyStarted()
    {
        var c = _clients.FirstOrDefault(x => string.Equals(x.Key, _sessionStarted, StringComparison.InvariantCultureIgnoreCase));

        try
        {
            c.Value.NotifyProcessStarted();
        }
        catch (Exception ex)
        {
            lock (_clients)
            {
                _clients.Remove(c);
            }
        }
    }

    private void NotifyFileProcessed(int idFile)
    {
        var c = _clients.FirstOrDefault(
            x => string.Equals(x.Key, _sessionStarted,
            StringComparison.InvariantCultureIgnoreCase)
            );

        try
        {
            c.Value.NotifyFileProcessed(idFile);
        }
        catch (Exception ex)
        {
            lock (_clients)
            {
                _clients.Remove(c);
            }
        }
    }

    private void NotifyProcessFinished()
    {
        //STILL SAME YOU HAVE IT. JUST IN CASE
        foreach (var c in _clients)
        {
            try
            {
                c.Value.NotifyProcessFinished();
            }
            catch (Exception ex)
            {
                lock (_clients)
                {
                    _clients.Remove(c);
                }
            }
        }
    }

    private static void NotifyProcessWorking(string idSesion = "")
    {
        if (string.IsNullOrEmpty(idSesion))
        {
            foreach (var c in _clients)
            {
                try
                {
                    c.Value.NotifyProcessWorking();
                }
                catch (Exception ex)
                {
                    lock (_clients)
                    {
                        _clients.Remove(c);
                    }
                }
            }
        }
        else
        {
            var c = _clients.FirstOrDefault(x => string.Equals(x.Key, idSesion, StringComparison.InvariantCultureIgnoreCase));

            try
            {
                c.Value.NotifyProcessWorking();
            }
            catch (Exception)
            {
                lock (_clients)
                {
                    _clients.Remove(c);
                }
            }
        }
    }
}

If you have a single instance behavior and an static field: the static field is shared between all connections, so for example _sessionStarted is always getting the status for last connections.

So I have changed the servicebehavior to PerSession to allow non-static fields to be preserved by each specific session/connection while static fields like List<KeyValuePair<string, IService1DuplexCallback>> _clients still being shared among them. This also implied that some methods are now non-static methods .