[原创]我的WCF之旅（2）：Endpoint Overview

WCF实际上是构建了一个框架，这个框架实现了在互联系统中各个Application之间如何通信。使得Developers和Architect在构建分布式系统中，无需在考虑如何去实现通信相关的问题，更加关注与系统的业务逻辑本身。而在WCF Infrastructure中，各个Application之间的通信是由Endpoint来实现的。

Endpoint的结构

Endpoint包含以下4个对象：

• Address: Address通过一个URI唯一地标识一个Endpoint，并告诉潜在的WCF service的调用者如何找到这个Endpoint。所以Address解决了Where to locate the WCF Service？
• Binding: Binding实现在Client和Service通信的所有底层细节。比如Client与Service之间传递的Message是如何编码的——text/XML, binary，MTOM；这种Message的传递是采用的哪种Transport——TCP, Http, Named Pipe, MSMQ; 以及采用怎样的机制解决Secure Messaging的问题——SSL，Message Level Security。所以Binding解决的是How to communicate with service？
• Contract: Contract的主要的作用是暴露某个WCF Service所提供的所有有效的Functionality。从Message Exchange的层面上讲，Contract实际上是抱每个Operation转化成为相对应的Message Exchange Pattern——MEP（Request/Response； One-way； Duplex）。所以Contract解决的是What functionalities do the Service provide？
• Behavior: Behavior的主要作用是定制Endpoint在运行时的一些必要的Behavior。比如Service 回调Client的Timeout；Client采用的Credential type；以及是否支持Transaction等。

当我们Host一个WCF Service的时候，我们必须给他定义一个或多个Endpoint，然后service通过这个定义的Endpoint进行监听来自Client端的请求。当我们的Application需要调用这个Service的时候，因为Client 和Service是通过Endpoint的进行通信的， 所以我们必须为我们的Application定义Client端的Endpoint。只有当Client的Endpoint和Service端某个Endpoint相互匹配（Service端可以为一个Service定义多个Endpoint），Client端的请求才能被Service端监听到。也就是说，我们只有在Client具有一个与Service端完全匹配的Endpoint，我们才能调用这个Service。而这种匹配是比较严格的，比如从匹配Address方面，Client端和Service端的Endpoint Address不仅仅在URI上要完全匹配Service， 他们的Headers也需要相互匹配。对于Binding, 一般地，Client需要有一个与Service端完全一样的Binding，他们之间才能通信。

Sample

首先给一个Sample，以便我们对在WCF Service Aplication中如何定义Endpoint有一个感性的认识。整个Solution的结构参照下图，我的上一篇Blog([原创]我的WCF之旅（1）：创建一个简单的WCF程序 )中有详细的介绍。你也可以通过后面的Link下载相应的Source Code（http://www.cnblogs.com/files/artech/Artech.WCFService.zip ）

1．Service Contract：Artech..WCfService.Contract/ServiceContract/IGeneralCalculator.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;

namespace Artech.WCFService.Contract
{
[ServiceContract]
publicinterfaceIGeneralCalculator
{
[OperationContract]
doubleAdd(doublex,doubley);
}
}

2. Service: Artech.WCFSerice.Service/GeneralCalculatorService.cs

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

using Artech.WCFService.Contract;

namespace Artech.WCFService.Service
{
publicclassGeneralCalculatorService:IGeneralCalculator
{
IGeneralCalculatorMembers#regionIGeneralCalculatorMembers

publicdoubleAdd(doublex,doubley)
{
returnx+y;
}

#endregion
}
}

3. Hosting: Artech.WCFService.Hosting/Program.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
using Artech.WCFService.Contract;
using Artech.WCFService.Service;
using System.ServiceModel.Description;

namespace Artech.WCFService.Hosting
{
classProgram
{
staticvoidMain(string[]args)
{
//HostCalculatorServiceViaCode();
HostCalculatorSerivceViaConfiguration();
}

/**////<summary>
///Hostingaserviceusingmanagedcodewithoutanyconfiguraitoninformation.
///Pleasenotethattherelatedconfigurationdatashouldberemovedbeforecallingthemethod.
///</summary>
staticvoidHostCalculatorServiceViaCode()
{
UrihttpBaseAddress=newUri("http://localhost:8888/generalCalculator");
UritcpBaseAddress=newUri("net.tcp://localhost:9999/generalCalculator");

using(ServiceHostcalculatorSerivceHost=newServiceHost(typeof(GeneralCalculatorService),httpBaseAddress,tcpBaseAddress))
{
BasicHttpBindinghttpBinding=newBasicHttpBinding();
NetTcpBindingtcpBinding=newNetTcpBinding();

calculatorSerivceHost.AddServiceEndpoint(typeof(IGeneralCalculator),httpBinding,string.Empty);
calculatorSerivceHost.AddServiceEndpoint(typeof(IGeneralCalculator),tcpBinding,string.Empty);

ServiceMetadataBehaviorbehavior=calculatorSerivceHost.Description.Behaviors.Find<ServiceMetadataBehavior>();
{
if(behavior==null)
{
behavior=newServiceMetadataBehavior();
behavior.HttpGetEnabled=true;
calculatorSerivceHost.Description.Behaviors.Add(behavior);
}
else
{
behavior.HttpGetEnabled=true;
}
}

calculatorSerivceHost.Opened+=delegate
{
Console.WriteLine("CalculatorServicehasbeguntolisten");
};

calculatorSerivceHost.Open();

Console.Read();
}
}

staticvoidHostCalculatorSerivceViaConfiguration()
{
using(ServiceHostcalculatorSerivceHost=newServiceHost(typeof(GeneralCalculatorService)))
{
calculatorSerivceHost.Opened+=delegate
{
Console.WriteLine("CalculatorServicehasbeguntolisten");
};

calculatorSerivceHost.Open();

Console.Read();
}
}
}
}

4. Service.svc: http://localhost/WCFService/ GeneralCalculatorService.svc

< %@ServiceHost Language ="C#" Debug ="true" Service ="Artech.WCFService.Service.GeneralCalculatorService" % >

5. Client: Artech.WCFService.Client/ GeneralCalculatorClient.cs & Program.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Channels;
using Artech.WCFService.Contract;

namespace Artech.WCFService.Client
{
classGeneralCalculatorClient:ClientBase<IGeneralCalculator>,IGeneralCalculator
{
publicGeneralCalculatorClient()
:base()
{}

publicGeneralCalculatorClient(stringendpointConfigurationName)
:base(endpointConfigurationName)
{}

publicGeneralCalculatorClient(Bindingbinding,EndpointAddressaddress)
:base(binding,address)
{}

IGeneralCalculatorMembers#regionIGeneralCalculatorMembers

publicdoubleAdd(doublex,doubley)
{
returnthis.Channel.Add(x,y);
}

#endregion
}
}

using System;
using System.Collections.Generic;
using System.Text;
using System.ServiceModel;
using System.ServiceModel.Channels;
using Artech.WCFService.Contract;

namespace Artech.WCFService.Client
{
classProgram
{
staticvoidMain()
{
try
{
//InvocateCalclatorServiceViaCode();

InvocateCalclatorServiceViaConfiguration();
}
catch(Exceptionex)
{
Console.WriteLine(ex.Message);
}

Console.Read();
}

staticvoidInvocateCalclatorServiceViaCode()
{
BindinghttpBinding=newBasicHttpBinding();
BindingtcpBinding=newNetTcpBinding();

EndpointAddresshttpAddress=newEndpointAddress("http://localhost:8888/generalCalculator");
EndpointAddresstcpAddress=newEndpointAddress("net.tcp://localhost:9999/generalCalculator");
EndpointAddresshttpAddress_iisHost=newEndpointAddress("http://localhost/wcfservice/GeneralCalculatorService.svc");

Console.WriteLine("Invocateself-hostcalculatorservice");

InvocateSelf-hostservice#regionInvocateSelf-hostservice
using(GeneralCalculatorClientcalculator_http=newGeneralCalculatorClient(httpBinding,httpAddress))
{
using(GeneralCalculatorClientcalculator_tcp=newGeneralCalculatorClient(tcpBinding,tcpAddress))
{
try
{
Console.WriteLine("Begintoinvocatecalculatorserviceviahttptransport");
Console.WriteLine("x+y={2}wherex={0}andy={1}",1,2,calculator_http.Add(1,2));

Console.WriteLine("Begintoinvocatecalculatorserviceviatcptransport");
Console.WriteLine("x+y={2}wherex={0}andy={1}",1,2,calculator_tcp.Add(1,2));
}
catch(Exceptionex)
{
Console.WriteLine(ex.Message);
}
}
}
#endregion

Console.WriteLine("\n\nInvocateIIS-hostcalculatorservice");

InvocateIIS-hostservice#regionInvocateIIS-hostservice
using(GeneralCalculatorClientcalculator=newGeneralCalculatorClient(httpBinding,httpAddress_iisHost))