WCF：异步调用长时间工作的服务

今天继续在讲解WCF方面的课程。关于长时间工作的服务，实现异步的方式有很多种，例如新开一个Thread去调用，或者采用添加引用后生成的Beginxxxx方法去做。本文介绍一种比较特殊的写法：直接通过回调委托实现。

1. 合约

using System.ServiceModel;

namespace Contracts
{
[ServiceContract]
public interface ILongworker
{
[OperationContract]
//[OperationContract(IsOneWay=true)]
//将该操作设置为IsOneWay，表示该操作不需要回复。客户端调用之后无需等待即可返回
//该模式下即便服务器端抛出异常也不会被客户端接收到。

void Dowork();

}
}

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2. 服务

using System;

namespace Services
{
public class LongworkService:Contracts.ILongworker
{
#region ILongworker 成员

public void Dowork()
{
//这是一个长时间工作的服务方法
System.Threading.Thread.Sleep(10000);//设置休眠10秒钟
Console.WriteLine("服务器执行完了操作");
}

#endregion

}
}

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3. 宿主

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

namespace LongworkServiceHost
{
class Program
{
static void Main(string[] args)
{
#region 长时间工作的服务
using (ServiceHost host =
new ServiceHost(
typeof(Services.LongworkService),
new Uri("http://localhost:8000/LongworkService")
))
{
host.AddServiceEndpoint(
"Contracts.ILongworker",
new BasicHttpBinding(),
"");

ServiceMetadataBehavior behavior = new ServiceMetadataBehavior();
behavior.HttpGetEnabled = true;
host.Description.Behaviors.Add(behavior);

host.AddServiceEndpoint(
"IMetadataExchange",
MetadataExchangeBindings.CreateMexHttpBinding(),
"mex");

host.Open();
Console.WriteLine("服务器已经准备好");
Console.Read();
}
#endregion
}
}
}

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4. 客户端

Contracts.ILongworker proxy =
new ChannelFactory<Contracts.ILongworker>(
new BasicHttpBinding(),
new EndpointAddress("http://localhost:8000/LongworkService")).CreateChannel();

Action action = new Action(() => { proxy.Dowork(); });//这一句必须这样写，而不能写成new Action(proxy.Dowork)，那样实现不了异步效果

Console.WriteLine("异步调用之前的工作");
action.BeginInvoke((a) => { Console.WriteLine("调用结束"); }, null);
Console.WriteLine("主程序继续其他的工作");

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