WCF: Retry when service is in fault state.

Service Host:

using System;
using System.Configuration;
using System.ServiceModel;
using System.ServiceModel.Activation;
using System.Web.Configuration;
using log4net;
using System.Threading;

namespace Test.Custom
{
    public class CustomServiceHostFactory : System.ServiceModel.Activation.WebServiceHostFactory
    {
        private static ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        protected override System.ServiceModel.ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
        {
            log4net.Config.XmlConfigurator.Configure();

            CustomServiceHost customServiceHost = new CustomServiceHost (serviceType, baseAddresses);
            log.Info("Create Service Host called");

            customServiceHost.incomingServiceType = serviceType;
            customServiceHost.incomingBaseAddresses = baseAddresses;
            customServiceHost.Faulted += customServiceHost.OnServiceHostFaulted;

            return customServiceHost;
        }
    }

    public class CustomServiceHost : ServiceHost
    {
        public Type incomingServiceType { get; set; }
        public Uri[] incomingBaseAddresses { get; set; }

        private int Attempts = 0;
        private bool isSuccess = false;

        private static ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        public CustomServiceHost (Type serviceType, params Uri[] baseAddresses)
            : base(serviceType, baseAddresses)
        {
            log.Info("CustomServiceHost constructor called");
        }

        protected override void ApplyConfiguration()
        {
            base.ApplyConfiguration();
        }

        public void OnServiceHostFaulted(object sender, EventArgs e)
        {
            log.Info("Host state is fault.");
            ICommunicationObject faultedHost = (ICommunicationObject)sender;
            faultedHost.Abort();

            faultedHost = new ServiceHost(this.incomingServiceType, this.incomingBaseAddresses);
            //faultedHost.Faulted += this.OnServiceHostFaulted;

            log.Info("Host state is " + faultedHost.State.ToString());

            if (Attempts < 5 && isSuccess == false)
            {
                Attempts++;
                log.Info("Retry to create server host for the" + Attempts + "time");
                try
                {
                    if (isSuccess == false)
                    {
                        Thread.Sleep(1 * 1000);
                    }
                    faultedHost.Open();
                    isSuccess = true;
                }
                catch (Exception ex)
                {
                    faultedHost.Abort();
                    log.Info("Host state is " + faultedHost.State.ToString());
                    log.Info("Exception:  " + ex.Message);
                }
            }
        }

        //protected override void OnFaulted()
        //{
        //    base.OnFaulted();
        //}

    }
}

1. 创建一个自定义的HostFactory，继承自WebServiceHostFactory;

2. 重载CreateServiceHost方法，并在方法内添加ServiceHost对象的Faulted的EventHandler处理；

3. 对自定义Faulted EventHandler方法根据需要加入Retry。

 

Service Client:

using Microsoft.ServiceBus;
using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading.Tasks;

namespace Test.WCF.ServiceBus.Client
{
    class Program
    {
        public static ChannelFactory<IMediaServicesManagementServiceChannel> testCF=null;
        static void Main(string[] args)
        {

            Retry(
                () =>
                {
                    bool flag = false;
                    var cf = new ChannelFactory<IMediaServicesManagementServiceChannel>(
                                   new NetTcpRelayBinding(),
                                   new EndpointAddress(ServiceBusEnvironment.CreateServiceUri("sb", "***Service Bus Name***", "***Relay Name***")));

                    cf.Endpoint.Behaviors.Add(new TransportClientEndpointBehavior { TokenProvider = TokenProvider.CreateSharedSecretTokenProvider("owner", "***Service Bus Token***") });

         
                    var ch1 = cf.CreateChannel();

                    try
                    {
                        Console.WriteLine(ch1.AddNumbers(3, 4));
                        flag = true;
                    }
                    catch
                    {
                        ch1.Abort();
                        flag = false;
                    }
                    finally
                    {
                        if (ch1 != null)
                        {
                            ch1.Close();
                        }
                    }
                    return flag;
                },
                5);
            


            Console.WriteLine("Press ENTER to close");
            Console.ReadLine();
        }

        public static void Retry(Func<bool> task, int times)
        {
            bool flag = false;
            
            for (int i = 0; i < times; i++ )
            {
                flag = task();
                
                if(flag==true)
                {
                    break;
                }
            }
        }


    }
}

 

Referece Links:

http://msdn.microsoft.com/en-us/library/windowsazure/hh966775.aspx