How to: Host and Run a Basic Windows Communication Foundation Service

• Open the Program.cs or Module.vb file and enter the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ServiceModel;//Uri和ServiceHost
using System.ServiceModel.Description;//ServiceMetadataBehavior
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.");
                Console.WriteLine("Press <ENTER> to terminate service.");
                Console.WriteLine();
                Console.ReadLine();

                // Close the ServiceHostBase to shutdown the service.
                selfHost.Close();
            }
            catch (CommunicationException ce)
            {
                Console.WriteLine("An exception occurred: {0}", ce.Message);
                selfHost.Abort();
            }
        }
    }
}

• Step 1 - Creates an instance of the Uri class to hold the base address of the service. Services are identified by a URL which contains a base address and an optional URI. 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”

创建一个Uri类的实例，来保存服务的基础地址。服务通过url来进行识别，url包含了基础地址以及可选的uri。基础地址的格式如下：[transport]://[machine-name or domain][:optional port#]/[optional URI segment]

calculator 服务的基地址，使用的是http传输，localhost，端口8000。URI部分为GettingStarted

• Step 2 – Creates an instance of the ServicHost class 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.

创建一个ServicHost 类的实例来托管服务。构造函数接受2个参数，实现了服务契约的类的类型，服务的基地址。

• Step 3 – Creates a ServiceEndpoint instance. A service endpoint is composed of an address, a binding, and a service contract. The ServiceEndpoint constructor therefore takes 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 used in this sample is WSHttpBinding which is a built-in binding that is used for connecting to endpoints that conform to the WS-* specifications. For more information about WCF bindings, see Windows Communication Foundation Bindings Overview. The address is appended to the base address to identify the endpoint. The address specified in this code is “Calculator” so the fully qualified address for the endpoint is“http://localhost:8000/GettingStartedService/Calculator”

创建ServiceEndpoint 的实例。服务终结点由地址，绑定，服务契约构成。服务终结点的构造函数需要服务契约的接口类型，绑定以及地址。服务契约是ICalculator，此接口定义了，并且在服务类型中实现。在这个示例中使用的绑定是WSHttpBinding，用来连接符合WS-*规范的终结点。地址附加到基地址上来识别终结点。这个代码示例中的地址指定为Calculator，所以这个终结点的完全限定地址为http://localhost:8000/GettingStartedService/Calculator

Important

Adding a service endpoint is optional when using .NET Framework 4 or later. In these versions, if no endpoints are added in 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.

重点：在.net4.0以及更新的版本中，添加服务终结点是可选的。如果在代码或配置中没有添加终结点，那么wcf会为每一个基地址和服务实现的契约添加默认的终结点。

• Step 4 – Enable metadata exchange. Clients will use metadata exchange to generate proxies that will be used to call the service operations. To enable metadata exchange create a ServiceMetadataBehaviorinstance, set it’s HttpGetEnabled property to true, and add the behavior to the Behaviors collection of the ServiceHost instance.

启用元数据交互。客户端使用元数据生成代理来调用服务操作。为了确保元数据交换，代码中需要创建一个ServiceMetadataBehavior对象，然后设置HttpGetEnabled属性为true。并且把这个行为添加到ServiceHost实例的Behaviors集合中。

• Step 5 – Open the ServiceHost to listen for incoming messages. Notice the code waits for the user to hit enter. If you do not do this, the app will close immediately and the service will shut down.Also notice a try/catch block used. After the ServiceHost has been instantiated, all other code is placed in a try/catch block. For more information about safely catching exceptions thrown by ServiceHost, seeAvoiding Problems with the Using Statement

打开ServiceHost来监听进来的消息。注意代码在等待用户enter。如果你没有做这个的话，app会立即关闭并且服务也会被关闭。

还需要注意的是，使用了try catch进行异常的捕获。在ServiceHost实例化之后，所以的代码都放在了try catch块中。

To verify the service is working   确认托管服务已经在工作