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How to: Host a WCF Service in a Managed Windows Service

This topic outlines the basic steps required to create a Windows Communication Foundation (WCF) service that is hosted by a Windows Service. The scenario is enabled by the managed Windows service hosting option that is a long-running WCF service hosted outside of Internet Information Services (IIS) in a secure environment that is not message activated. The lifetime of the service is controlled instead by the operating system. This hosting option is available in all versions of Windows.

Windows services can be managed with the Microsoft.ManagementConsole.SnapIn in Microsoft Management Console (MMC) and can be configured to start up automatically when the system boots up. This hosting option consists of registering the application domain (AppDomain) that hosts a WCF service as a managed Windows service so that the process lifetime of the service is controlled by the Service Control Manager (SCM) for Windows services.

The service code includes a service implementation of the service contract, a Windows Service class, and an installer class. The service implementation class, CalculatorService, is a WCF service. The CalculatorWindowsService is a Windows service. To qualify as a Windows service, the class inherits from ServiceBase and implements the OnStart and OnStop methods. In OnStart, a ServiceHost is created for the CalculatorService type and opened. In OnStop, the service is stopped and disposed. The host is also responsible for providing a base address to the service host, which has been configured in application settings. The installer class, which inherits from Installer, allows the program to be installed as a Windows service by the Installutil.exe tool.

Construct the service and provide the hosting code

  1. Create a new Visual Studio Console Application project called "Service".

  2. Rename Program.cs to Service.cs.

  3. Change the namespace to Microsoft.ServiceModel.Samples.

  4. Add references to the following assemblies.

    • System.ServiceModel.dll

    • System.ServiceProcess.dll

    • System.Configuration.Install.dll

  5. Add the following using statements to Service.cs.

    using System.ComponentModel;
    using System.ServiceModel;
    using System.ServiceProcess;
    using System.Configuration;
    using System.Configuration.Install;
    
    
  6. Define the ICalculator service contract as shown in the following code.

    // Define a service contract.
    [ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
    public interface ICalculator
    {
        [OperationContract]
        double Add(double n1, double n2);
        [OperationContract]
        double Subtract(double n1, double n2);
        [OperationContract]
        double Multiply(double n1, double n2);
        [OperationContract]
        double Divide(double n1, double n2);
    }
    
    
  7. Implement the service contract in a class called CalculatorService as shown in the following code.

    // Implement the ICalculator service contract in a service class.
    public class CalculatorService : ICalculator
    {
        // Implement the ICalculator methods.
        public double Add(double n1, double n2)
        {
            double result = n1 + n2;
            return result;
        }
    
        public double Subtract(double n1, double n2)
        {
            double result = n1 - n2;
            return result;
        }
    
        public double Multiply(double n1, double n2)
        {
            double result = n1 * n2;
            return result;
        }
    
        public double Divide(double n1, double n2)
        {
            double result = n1 / n2;
            return result;
        }
    }
    
    
  8. Create a new class called CalculatorWindowsService that inherits from the ServiceBase class. Add a local variable called serviceHost to reference the ServiceHost instance. Define the Main method that calls ServiceBase.Run(new CalculatorWindowsService)

    public class CalculatorWindowsService : ServiceBase
    {
        public ServiceHost serviceHost = null;
        public CalculatorWindowsService()
        {
            // Name the Windows Service
            ServiceName = "WCFWindowsServiceSample";
        }
    
        public static void Main()
        {
            ServiceBase.Run(new CalculatorWindowsService());
        }
    
    
  9. Override the OnStart method by creating and opening a new ServiceHost instance as shown in the following code.

    // Start the Windows service.
    protected override void OnStart(string[] args)
    {
        if (serviceHost != null)
        {
            serviceHost.Close();
        }
    
        // Create a ServiceHost for the CalculatorService type and 
        // provide the base address.
        serviceHost = new ServiceHost(typeof(CalculatorService));
    
        // Open the ServiceHostBase to create listeners and start 
        // listening for messages.
        serviceHost.Open();
    }
    
    
  10. Override the OnStop method closing the ServiceHost as shown in the following code.

    protected override void OnStop()
    {
        if (serviceHost != null)
        {
            serviceHost.Close();
            serviceHost = null;
        }
    }
    
    
  11. Create a new class called ProjectInstaller that inherits from Installer and that is marked with the RunInstallerAttribute set to true. This allows the Windows service to be installed by the Installutil.exe tool.

    // Provide the ProjectInstaller class which allows 
    // the service to be installed by the Installutil.exe tool
    [RunInstaller(true)]
    public class ProjectInstaller : Installer
    {
        private ServiceProcessInstaller process;
        private ServiceInstaller service;
    
        public ProjectInstaller()
        {
            process = new ServiceProcessInstaller();
            process.Account = ServiceAccount.LocalSystem;
            service = new ServiceInstaller();
            service.ServiceName = "WCFWindowsServiceSample";
            Installers.Add(process);
            Installers.Add(service);
        }
    }
    
    
  12. Remove the Service class that was generated when you created the project.

  13. Add an application configuration file to the project. Replace the contents of the file with the following configuration XML.

    <?xml version="1.0" encoding="utf-8" ?>
    <configuration>
      <system.serviceModel>    <services>
          <!-- This section is optional with the new configuration model
               introduced in .NET Framework 4. -->
          <service name="Microsoft.ServiceModel.Samples.CalculatorService"
                   behaviorConfiguration="CalculatorServiceBehavior">
            <host>
              <baseAddresses>
                <add baseAddress="http://localhost:8000/ServiceModelSamples/service"/>
              </baseAddresses>
            </host>
            <!-- this endpoint is exposed at the base address provided by host: http://localhost:8000/ServiceModelSamples/service  -->
            <endpoint address=""
                      binding="wsHttpBinding"
                      contract="Microsoft.ServiceModel.Samples.ICalculator" />
            <!-- the mex endpoint is exposed at http://localhost:8000/ServiceModelSamples/service/mex -->
            <endpoint address="mex"
                      binding="mexHttpBinding"
                      contract="IMetadataExchange" />
          </service>
        </services>
        <behaviors>
          <serviceBehaviors>
            <behavior name="CalculatorServiceBehavior">
              <serviceMetadata httpGetEnabled="true"/>
              <serviceDebug includeExceptionDetailInFaults="False"/>
            </behavior>
          </serviceBehaviors>
        </behaviors>
      </system.serviceModel>
    </configuration>
    

    Right click the App.config file in the Solution Explorer and select Properties. Under Copy to Output Directory select Copy if Newer.

    This example explicitly specifies endpoints in the configuration file. If you do not add any endpoints to the service, the runtime adds default endpoints for you. In this example, because the service has a ServiceMetadataBehavior set to true, your service also has publishing metadata enabled. For more information aboutdefault endpoints, bindings, and behaviors, see Simplified Configuration and Simplified Configuration for WCF Services.

Install and run the service

  1. Build the solution to create the Service.exe executable.

  2. Open the Visual Studio 2010 command prompt and navigate to the project directory. Type installutil bin\service.exe at the command prompt to install the Windows service.

    ms733069.note(en-us,VS.100).gifNote:
    If you do not use the Visual Studio 2010 command prompt, make sure that the %WinDir%\Microsoft.NET\Framework\v4.0.<current version> directory is in the system path.

    Type services.msc at the command prompt to access the Service Control Manager (SCM). The Windows service should appear in Services as "WCFWindowsServiceSample". The WCF service can only respond to clients if the Windows service is running. To start the service, right-click it in the SCM and select "Start", or type net start WCFWindowsServiceSample at the command prompt.

  3. If you make changes to the service, you must first stop it and uninstall it. To stop the service, right-click the service in the SCM and select "Stop", or type net stop WCFWindowsServiceSample at the command prompt. Note that if you stop the Windows service and then run a client, an EndpointNotFoundException exception occurs when a client attempts to access the service. To uninstall the Windows service type installutil /u bin\service.exe at the command prompt.

Example

The following is a complete listing of the code used by this topic.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.ComponentModel;
using System.ServiceModel;
using System.ServiceProcess;
using System.Configuration;
using System.Configuration.Install;

namespace Microsoft.ServiceModel.Samples
{
    // Define a service contract.
    [ServiceContract(Namespace = "http://Microsoft.ServiceModel.Samples")]
    public interface ICalculator
    {
        [OperationContract]
        double Add(double n1, double n2);
        [OperationContract]
        double Subtract(double n1, double n2);
        [OperationContract]
        double Multiply(double n1, double n2);
        [OperationContract]
        double Divide(double n1, double n2);
    }

    // Implement the ICalculator service contract in a service class.
    public class CalculatorService : ICalculator
    {
        // Implement the ICalculator methods.
        public double Add(double n1, double n2)
        {
            double result = n1 + n2;
            return result;
        }

        public double Subtract(double n1, double n2)
        {
            double result = n1 - n2;
            return result;
        }

        public double Multiply(double n1, double n2)
        {
            double result = n1 * n2;
            return result;
        }

        public double Divide(double n1, double n2)
        {
            double result = n1 / n2;
            return result;
        }
    }

    public class CalculatorWindowsService : ServiceBase
    {
        public ServiceHost serviceHost = null;
        public CalculatorWindowsService()
        {
            // Name the Windows Service
            ServiceName = "WCFWindowsServiceSample";
        }

        public static void Main()
        {
            ServiceBase.Run(new CalculatorWindowsService());
        }

        // Start the Windows service.
        protected override void OnStart(string[] args)
        {
            if (serviceHost != null)
            {
                serviceHost.Close();
            }

            // Create a ServiceHost for the CalculatorService type and 
            // provide the base address.
            serviceHost = new ServiceHost(typeof(CalculatorService));

            // Open the ServiceHostBase to create listeners and start 
            // listening for messages.
            serviceHost.Open();
        }

        protected override void OnStop()
        {
            if (serviceHost != null)
            {
                serviceHost.Close();
                serviceHost = null;
            }
        }
    }

    // Provide the ProjectInstaller class which allows 
    // the service to be installed by the Installutil.exe tool
    [RunInstaller(true)]
    public class ProjectInstaller : Installer
    {
        private ServiceProcessInstaller process;
        private ServiceInstaller service;

        public ProjectInstaller()
        {
            process = new ServiceProcessInstaller();
            process.Account = ServiceAccount.LocalSystem;
            service = new ServiceInstaller();
            service.ServiceName = "WCFWindowsServiceSample";
            Installers.Add(process);
            Installers.Add(service);
        }
    }
}

Like the "Self-Hosting" option, the Windows service hosting environment requires that some hosting code be written as part of the application. The service is implemented as a console application and contains its own hosting code. In other hosting environments, such as Windows Process Activation Service (WAS) hosting in Internet Information Services (IIS), it is not necessary for developers to write hosting code.

See Also

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