WCF技术剖析之二十九：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: <?xml version="1.0" encoding="utf-8" ?>using System.ServiceModel; 2: <configuration>namespace Artech.ServiceInvocationViaMetadata.Contracts 3: { 4: 5: public interface ICalculator 6: { 7: 8: double Add(double x, double y); 9: }10: }服务类型：
1: <?xml version="1.0" encoding="utf-8" ?>using System.ServiceModel; 2: <configuration>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: </behaviors> return x + y;11: <services>}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对象，并创建服务代理进行服务调用。
1: <?xml version="1.0" encoding="utf-8" ?>sing System; 2: <configuration>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: </behaviors>static void Main(string[] args)11: <services>{12: <service behaviorConfiguration="mexBehavior" name="Artech.ServiceInvocationViaMetadata.Services.CalculatorService">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: </service>//添加已知契约类型16: </services> ContractDescription contract = ContractDescription.GetContract(typeof(ICalculator));17: </system.serviceModel> wsdlImporter.KnownContracts.Add(new XmlQualifiedName(contract.Name, contract.Namespace), contract);18: </configuration> ServiceEndpointCollection endpoints = wsdlImporter.ImportAllEndpoints();19: using (ChannelFactory<ICalculator> channelFactory = new ChannelFactory<ICalculator>(endpoints))20: {21: ICalculator calculator = channelFactory.CreateChannel();22: using (calculator as IDisposable)23: {24: try25: {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: }
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