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Tutorial: Host and run a basic Windows Communication Foundation service

  • Άρθρο

This tutorial describes the third of five tasks required to create a basic Windows Communication Foundation (WCF) application. For an overview of the tutorials, see Tutorial: Get started with Windows Communication Foundation applications.

The next task for creating a WCF application is to host a WCF service in a console application. A WCF service exposes one or more endpoints, each of which exposes one or more service operations. A service endpoint specifies the following information:

  • An address where you can find the service.
  • A binding that contains the information that describes how a client must communicate with the service.
  • A contract that defines the functionality that the service provides to its clients.

In this tutorial, you learn how to:

  • Create and configure a console app project for hosting a WCF service.
  • Add code to host the WCF service.
  • Update the configuration file.
  • Start the WCF service and verify it's running.

Create and configure a console app project for hosting the service

  1. Create a console app project in Visual Studio:

    1. From the File menu, select Open > Project/Solution and browse to the GettingStarted solution you previously created (GettingStarted.sln). Select Open.

    2. From the View menu, select Solution Explorer.

    3. In the Solution Explorer window, select the GettingStarted solution (top node), and then select Add > New Project from the shortcut menu.

    4. In the Add New Project window, on the left side, select the Windows Desktop category under Visual C# or Visual Basic.

    5. Select the Console App (.NET Framework) template, and enter GettingStartedHost for the Name. Select OK.

  2. Add a reference in the GettingStartedHost project to the GettingStartedLib project:

    1. In the Solution Explorer window, select the References folder under the GettingStartedHost project, and then select Add Reference from the shortcut menu.

    2. In the Add Reference dialog, under Projects on the left side of the window, select Solution.

    3. Select GettingStartedLib in the center section of the window, and then select OK.

      This action makes the types defined in the GettingStartedLib project available to the GettingStartedHost project.

  3. Add a reference in the GettingStartedHost project to the System.ServiceModel assembly:

    1. In the Solution Explorer window, select the References folder under the GettingStartedHost project, and then select Add Reference from the shortcut menu.

    2. In the Add Reference window, under Assemblies on the left side of the window, select Framework.

    3. Select System.ServiceModel, and then select OK.

    4. Save the solution by selecting File > Save All.

Add code to host the service

To host the service, you add code to do the following steps:

  1. Create a URI for the base address.
  2. Create a class instance for hosting the service.
  3. Create a service endpoint.
  4. Enable metadata exchange.
  5. Open the service host to listen for incoming messages.

Make the following changes to the code:

  1. Open the Program.cs or Module1.vb file in the GettingStartedHost project and replace its code with the following code:

    using System;
using System.ServiceModel;
using System.ServiceModel.Description;
using GettingStartedLib;

namespace GettingStartedHost
{
    class Program
    {
        static void Main(string[] args)
        {
            // Step 1: Create a URI to serve as the base address.
            Uri baseAddress = new Uri("http://localhost:8000/GettingStarted/");

            // Step 2: Create a ServiceHost instance.
            ServiceHost selfHost = new ServiceHost(typeof(CalculatorService), baseAddress);

            try
            {
                // Step 3: Add a service endpoint.
                selfHost.AddServiceEndpoint(typeof(ICalculator), new WSHttpBinding(), "CalculatorService");

                // Step 4: Enable metadata exchange.
                ServiceMetadataBehavior smb = new ServiceMetadataBehavior();
                smb.HttpGetEnabled = true;
                selfHost.Description.Behaviors.Add(smb);

                // Step 5: Start the service.
                selfHost.Open();
                Console.WriteLine("The service is ready.");

                // Close the ServiceHost to stop the service.
                Console.WriteLine("Press <Enter> to terminate the service.");
                Console.WriteLine();
                Console.ReadLine();
                selfHost.Close();
            }
            catch (CommunicationException ce)
            {
                Console.WriteLine("An exception occurred: {0}", ce.Message);
                selfHost.Abort();
            }
        }
    }
}

    Imports System.ServiceModel
Imports System.ServiceModel.Description
Imports GettingStartedLib.GettingStartedLib

Module Service

    Class Program
        Shared Sub Main()
            ' Step 1: Create a URI to serve as the base address.
            Dim baseAddress As New Uri("http://localhost:8000/GettingStarted/")

            ' Step 2: Create a ServiceHost instance.
            Dim selfHost As New ServiceHost(GetType(CalculatorService), baseAddress)
           Try

                ' Step 3: Add a service endpoint.
                selfHost.AddServiceEndpoint( _
                    GetType(ICalculator), _
                    New WSHttpBinding(), _
                    "CalculatorService")

                ' Step 4: Enable metadata exchange.
                Dim smb As New ServiceMetadataBehavior()
                smb.HttpGetEnabled = True
                selfHost.Description.Behaviors.Add(smb)

                ' Step 5: Start the service.
                selfHost.Open()
                Console.WriteLine("The service is ready.")

                ' Close the ServiceHost to stop the service.
                Console.WriteLine("Press <Enter> to terminate the service.")
                Console.WriteLine()
                Console.ReadLine()
                selfHost.Close()

            Catch ce As CommunicationException
                Console.WriteLine("An exception occurred: {0}", ce.Message)
                selfHost.Abort()
            End Try
        End Sub
    End Class

End Module

    For information about how this code works, see Service hosting program steps.

  2. Update the project properties:

    1. In the Solution Explorer window, select the GettingStartedHost folder, and then select Properties from the shortcut menu.

    2. On the GettingStartedHost properties page, select the Application tab:

      • For C# projects, select GettingStartedHost.Program from the Startup object list.

      • For Visual Basic projects, select Service.Program from the Startup object list.

    3. From the File menu, select Save All.

Verify the service is working

  1. Build the solution, and then run the GettingStartedHost console application from inside Visual Studio.

    The service must be run with administrator privileges. Because you opened Visual Studio with administrator privileges, when you run GettingStartedHost in Visual Studio, the application is run with administrator privileges as well. As an alternative, you can open a new command prompt as an administrator (select More > Run as administrator from the shortcut menu) and run GettingStartedHost.exe within it.

  2. Open a web browser and browse to the service's page at http://localhost:8000/GettingStarted/.

    Note

    Services such as this one require the proper permission to register HTTP addresses on the machine for listening. Administrator accounts have this permission, but non-administrator accounts must be granted permission for HTTP namespaces. For more information about how to configure namespace reservations, see Configuring HTTP and HTTPS.

Service hosting program steps

The steps in the code you added to host the service are described as follows:

  • Step 1: Create an instance of the Uri class to hold the base address of the service. A URL that contains a base address has an optional URI that identifies a service. The base address is formatted as follows: <transport>://<machine-name or domain><:optional port #>/<optional URI segment>. The base address for the calculator service uses the HTTP transport, localhost, port 8000, and the URI segment, GettingStarted.

  • Step 2: Create an instance of the ServiceHost class, which you use to host the service. The constructor takes two parameters: the type of the class that implements the service contract and the base address of the service.

  • Step 3: Create a ServiceEndpoint instance. A service endpoint is composed of an address, a binding, and a service contract. The ServiceEndpoint constructor is composed of the service contract interface type, a binding, and an address. The service contract is ICalculator, which you defined and implement in the service type. The binding for this sample is WSHttpBinding, which is a built-in binding and connects to endpoints that conform to the WS-* specifications. For more information about WCF bindings, see WCF bindings overview. You append the address to the base address to identify the endpoint. The code specifies the address as CalculatorService and the fully qualified address for the endpoint as http://localhost:8000/GettingStarted/CalculatorService.

    Important

    For .NET Framework Version 4 and later, adding a service endpoint is optional. For these versions, if you don't add your code or configuration, WCF adds one default endpoint for each combination of base address and contract implemented by the service. For more information about default endpoints, see Specifying an endpoint address. For more information about default endpoints, bindings, and behaviors, see Simplified configuration and Simplified configuration for WCF services.

  • Step 4: Enable metadata exchange. Clients use metadata exchange to generate proxies for calling the service operations. To enable metadata exchange, create a ServiceMetadataBehavior instance, set its HttpGetEnabled property to true, and add the ServiceMetadataBehavior object to the Behaviors collection of the ServiceHost instance.

  • Step 5: Open ServiceHost to listen for incoming messages. The application waits for you to press Enter. After the application instantiates ServiceHost, it executes a try/catch block. For more information about safely catching exceptions thrown by ServiceHost, see Use Close and Abort to release WCF client resources.

Important

When you add a WCF service library, Visual Studio hosts it for you if you debug it by starting a service host. To avoid conflicts, you can prevent Visual Studio from hosting the WCF service library.

  1. Select the GettingStartedLib project in Solution Explorer and choose Properties from the shortcut menu.
  2. Select WCF Options and uncheck Start WCF Service Host when debugging another project in the same solution.

Next steps

In this tutorial, you learned how to:

  • Create and configure a console app project for hosting a WCF service.
  • Add code to host the WCF service.
  • Update the configuration file.
  • Start the WCF service and verify it's running.

Advance to the next tutorial to learn how to create a WCF client.

Tutorial: Create a WCF client