WCF技术剖析之二十七: 如何将一个服务发布成WSDL[基于HTTP-GET的实现]

（提供模拟程序）

基于HTTP-GET的元数据发布方式与基于WS-MEX原理类似,但是ServiceMetadataBehavior需要做的更多额外的工作。原因很简单，由于在WS-MEX模式下，我们为寄宿的服务添加了相应的MEX终结点，那么当服务被成功寄宿后，WCF已经为元数据的消息交换建立了如图1所示的分发体系，我们需要做的仅仅是对MEX终结点的DispatchRuntime进行相应的定制而已。

图1 WCF服务端分发体系

但是如果采用HTTP-GET模式，实际上我们需要从ChannelDispatcher开始，重新构建整个分发体系。接下来，我们在《WS-MEX原理》提供实例的基础上，对我们自定义ServiceMetadataBehaviorAttribute进行进一步的完善，使之同时对两种模式的元数据发布提供支持。 （Source Code从这里下载）

首先，我们需要定义一个新的服务契约接口：IHttpGetMetadata，Get操作处理任何形式的消息请求，因为它的输入参数和返回类型均为Message，并且Action和ReplyAction为*。

   1: using System.ServiceModel;   2: using System.ServiceModel.Channels;   3: namespace ServiceMetadataBehaviorSimulator   4: {   5:     [ServiceContract(Name = "IHttpGetMetadata", Namespace = "http://www.artech.com/")]   6:     public interface IHttpGetMetadata   7:     {   8:         [OperationContract(Action = "*", ReplyAction = "*")]   9:         Message Get(Message msg);  10:     }  11: }

然后我们让前面定义的MetadataProvisionService实现IHttpGetMetadata接口，在这里无需再写任何多余的代码，因为MetadataProvisionService已经具有了一个Get方法。

   1: public class MetadataProvisionService : IMetadataProvisionService, IHttpGetMetadata   2: {   3:       //省略成员   4: }

接下来的工作就是构建一个全新的ChannelDispatcher，以及关联EndpointDispatcher，最后对EndpointDispatcher的DispatchRuntime进行定制。为此，我单独写了一个方法：CreateHttpGetChannelDispatcher。

   1: [AttributeUsage(AttributeTargets.Class)]   2: public class ServiceMetadataBehaviorAttribute : Attribute, IServiceBehavior   3: {   4:     //其他成员   5: private const string SingletonInstanceContextProviderType = "System.ServiceModel.Dispatcher.SingletonInstanceContextProvider,System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089";   6:      private const string SyncMethodInvokerType = "System.ServiceModel.Dispatcher.SyncMethodInvoker,System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089";   7:      private const string MessageOperationFormatterType = "System.ServiceModel.Dispatcher.MessageOperationFormatter, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089";   8:   9:     private static void CreateHttpGetChannelDispatcher(ServiceHostBase host, Uri listenUri, MetadataSet metadata)  10:     {  11:         //创建Binding  12:         TextMessageEncodingBindingElement messageEncodingElement = new TextMessageEncodingBindingElement() { MessageVersion = MessageVersion.None };  13:         HttpTransportBindingElement transportElement = new HttpTransportBindingElement();  14:         Utility.SetPropertyValue(transportElement, "Method", "GET");  15:         Binding binding = new CustomBinding(messageEncodingElement, transportElement);  16:  17:         //创建ChannelListener  18:         IChannelListener listener = binding.BuildChannelListener<IReplyChannel>(listenUri, string.Empty, ListenUriMode.Explicit, new BindingParameterCollection());  19:         ChannelDispatcher dispatcher = new ChannelDispatcher(listener, "ServiceMetadataBehaviorHttpGetBinding", binding) { MessageVersion = binding.MessageVersion };  20:  21:         //创建EndpointDispatcher  22:         EndpointDispatcher endpoint = new EndpointDispatcher(new EndpointAddress(listenUri), "IHttpGetMetadata", "http://www.artech.com/");  23:  24:         //创建DispatchOperation，并设置DispatchMessageFormatter和OperationInvoker  25:         DispatchOperation operation = new DispatchOperation(endpoint.DispatchRuntime, "Get", "*", "*");  26:         operation.Formatter = Utility.CreateInstance<IDispatchMessageFormatter>(MessageOperationFormatterType, Type.EmptyTypes, new object[0]);  27:         MethodInfo method = typeof(IHttpGetMetadata).GetMethod("Get");  28:         operation.Invoker = Utility.CreateInstance<IOperationInvoker>(SyncMethodInvokerType, new Type[] { typeof(MethodInfo) }, new object[] { method });  29:         endpoint.DispatchRuntime.Operations.Add(operation);  30:  31:         //设置SingletonInstanceContext和InstanceContextProvider  32:         MetadataProvisionService serviceInstance = new MetadataProvisionService(metadata);  33:         endpoint.DispatchRuntime.SingletonInstanceContext = new InstanceContext(host, serviceInstance);  34:         endpoint.DispatchRuntime.InstanceContextProvider = Utility.CreateInstance<IInstanceContextProvider>(SingletonInstanceContextProviderType, new Type[] { typeof(DispatchRuntime) }, new object[] { endpoint.DispatchRuntime });  35:         dispatcher.Endpoints.Add(endpoint);  36:  37:         //设置ContractFilter和AddressFilter  38:         endpoint.ContractFilter = new MatchAllMessageFilter();  39:         endpoint.AddressFilter = new MatchAllMessageFilter();  40:  41:         host.ChannelDispatchers.Add(dispatcher);  42:     }  43: }

以上是小编为您精心准备的的内容，在的博客、问答、公众号、人物、课程等栏目也有的相关内容，欢迎继续使用右上角搜索按钮进行搜索new
， system
， endpoint
serviceModel
sql 发布wsdl服务、springmvc发布wsdl、webservice发布wsdl、php wsdl 调用实现、发布wsdl，以便于您获取更多的相关知识。