换种不同的方式调用WCF服务[提供源代码下载]
我们有两种典型的WCF调用方式：通过SvcUtil.exe（或者添加Web引用）导入发布的服务元数据生成服务代理相关的代码和配置；通过ChannelFactory<TChannel>创建服务代理对象。在这篇文章中，我们采用一种独特的方式进行服务的调用。从本质上讲，我们只要能够创建于服务端相匹配的终结点，就能够实现正常的服务调用。在WCF客户端元数据架构体系中，利用MetadataExchangeClient可以获取服务的元数据，而利用MetadataImporter将获取的元数据导入成ServiceEndpoint对象。在本例中，我们将利用这两个组件定义了一个独特的服务调用的简单的例子，相信可以帮助读者进一步加深对WCF元数据框架体系的理解。 (Source从这里下载)
我们依然采用我们熟悉的计算服务的例子，下面是该服务相应的服务契约、服务类型的定义和寄宿该服务采用的配置。
1: using System.ServiceModel;
2: namespace Artech.ServiceInvocationViaMetadata.Contracts
3: {4: [ServiceContract(Namespace = "http://www.artech.com/")]
5: public interface ICalculator
6: {7: [OperationContract]
8: double Add(double x, double y);
9: }
10: }
服务类型：
1: using System.ServiceModel;
2: using Artech.ServiceInvocationViaMetadata.Contracts;
3:
4: namespace Artech.ServiceInvocationViaMetadata.Services
5: {6: public class CalculatorService : ICalculator
7: {8: public double Add(double x, double y)
9: {10: return x + y;
11: }
12: }
13: }
配置：
1: <?xml version="1.0" encoding="utf-8" ?>
2: <configuration>
3: <system.serviceModel>
4: <behaviors>
5: <serviceBehaviors>
6: <behavior name="mexBehavior">
7: <serviceMetadata />
8: </behavior>
9: </serviceBehaviors>
10: </behaviors>
11: <services>
12: <service behaviorConfiguration="mexBehavior" name="Artech.ServiceInvocationViaMetadata.Services.CalculatorService">
13: <endpoint address="http://127.0.0.1:3721/calculatorservice" binding="ws2007HttpBinding" contract="Artech.ServiceInvocationViaMetadata.Contracts.ICalculator" />
14: <endpoint address="http://127.0.0.1:3721/calculatorservice/mex" binding="mexHttpBinding" contract="IMetadataExchange" />
15: </service>
16: </services>
17: </system.serviceModel>
18: </configuration>
从上面的配置我们可以看到，服务的元数据通过WS-MEX模式发布出来，发布的地址和采用的MEX绑定分别为：http://127.0.0.1:3721/calculatorservice/mex和mexHttpBinding。
接下来，我们就可以通过下面的方式对该服务进行调用了。我们先创建MetadataExchangeClient对象并利用它获取包含元数据的MetadataSet对象，并利用该对象创建WsdlImporter对象。接下来，我们将基于ICalculator接口的服务契约添加到该WsdlImporter的已知契约列表中，调用ImportAllEndpoints方法得到导入的ServiceEndpoint列表。最后根据导出的ServiceEndpoint对象创建ChannelFactory<ICalculator>对象，并创建服务代理进行服务调用。
1: sing System;
2: using System.ServiceModel;
3: using System.ServiceModel.Description;
4: using System.Xml;
5: using Artech.ServiceInvocationViaMetadata.Contracts;
6: namespace Artech.ServiceInvocationViaMetadata.Client
7: {8: class Program
9: {10: static void Main(string[] args)
11: {12: MetadataExchangeClient metadataExchangeClient = new MetadataExchangeClient(MetadataExchangeBindings.CreateMexHttpBinding());
13: MetadataSet metadata = metadataExchangeClient.GetMetadata(new EndpointAddress("http://127.0.0.1:3721/calculatorservice/mex"));14: WsdlImporter wsdlImporter = new WsdlImporter(metadata);
15: //添加已知契约类型
16: ContractDescription contract = ContractDescription.GetContract(typeof(ICalculator));
17: wsdlImporter.KnownContracts.Add(new XmlQualifiedName(contract.Name, contract.Namespace), contract);
18: ServiceEndpointCollection endpoints = wsdlImporter.ImportAllEndpoints();
19: using (ChannelFactory<ICalculator> channelFactory = new ChannelFactory<ICalculator>(endpoints[0]))
20: {21: ICalculator calculator = channelFactory.CreateChannel();
22: using (calculator as IDisposable)
23: {24: try
25: {26: Console.WriteLine("x + y = {2} when x = {0} and y = {1}", 1, 2, calculator.Add(1, 2));27: }
28: catch(TimeoutException)
29: {30: (calculator as ICommunicationObject).Abort();
31: throw;
32: }
33: catch(CommunicationException)
34: {35: (calculator as ICommunicationObject).Abort();
36: throw;
37: }
38: }
39: }
40: Console.Read();
41: }
42: }
43: }