WCF的异步调用

namespace Contracts
{
    [ServiceContract]
   public interface ICalculator
    {
        [OperationContract]
       double Add(double x,double y);
    }
}

namespace Services
{
   public class CalculatorService:ICalculator
    {
       public double Add(double x, double y)
       {
           return x + y;
       }
    }
}

namespace Hosting
{
    class Program
    {
        static void Main(string[] args)
        {

                //通过配置文件获取相应的信息
                using (ServiceHost host = new ServiceHost(typeof(CalculatorService)))
                {
                    
                    host.Opened += delegate
                    {
                        Console.WriteLine("服务已经启动，按任意键停止");
                    };
                    host.Open();
                    Console.Read();
                }
            
        }
    }
}

<configuration>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior name="metadataBehavior">
          <serviceMetadata httpGetEnabled="true" httpGetUrl="http://127.0.0.1:6666/calculatorservice/metadata"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <services>
      <service behaviorConfiguration="metadataBehavior" name="Services.CalculatorService">
        <endpoint address="http://127.0.0.1:6666/calculatorservice" binding="wsHttpBinding" contract="Contracts.ICalculator"  ></endpoint>
      </service>
    </services>
  </system.serviceModel>
</configuration>

namespace Client
{
    class Program
    {
        static void Main(string[] args)
        {
            //通过回调的方式进行异步服务调用
            //通过上面的方式进行异步调用有一个不好的地方，就是当EndAdd方法被执行的时候
            //如果异步执行的方法Add没有执行结束的话，该方法将会阻塞当前线程并等待异步
            //方法的结束，这样往往不能起到多线程并发执行应有的作用。我么真正希望的是在
            //异步执行结束后自动回调设定的操作，这样就可以采用回调的方式来实现这样的机制。
            ServiceCalculator.CalculatorClient proxy = new Client.ServiceCalculator.CalculatorClient();
            proxy.BeginAdd(1, 2, delegate(IAsyncResult asyncResult)
            {double result = proxy.EndAdd(asyncResult);
                proxy.Close();
                Console.WriteLine("x+y={2} when x={0} and y={1}", operands[0], operands[1], result);
            }, null);
            Console.Read();
        }
    }
}