9

我有一个作为 Windows 服务托管的 WCF Restful 服务。我想为我的服务添加跨域支持。但是，当我使用 global.asax 文件时，我可以轻松地做到这一点。但我想将我的服务托管为 Windows 服务。

我创建了一个项目，将我的服务托管为 Windows 服务。现在我面临的问题是，我现在无法添加跨域支持。我尝试了通过 app.config 文件找到的所有可能的解决方案，但没有一个可行。我在这些链接上尝试了解决方案：

点网技巧

启用-cors.org

我尝试通过在每个服务合同方法中调用以下函数来设置代码中的标头。

private static void SetResponseHeader()
{
WebOperationContext.Current.OutgoingResponse.Headers.Add("Access-Control-Allow-Origin", "*");
WebOperationContext.Current.OutgoingResponse.Headers.Add("Cache-Control", "no-cache, no-store");
WebOperationContext.Current.OutgoingResponse.Headers.Add("Access-Control-Request-Methods", "GET, POST, PUT, DELETE, OPTIONS");
WebOperationContext.Current.OutgoingResponse.Headers.Add("Access-Control-Allow-Headers", "Content-Type, Accept");
}

界面：

namespace ReaderService
{
[ServiceContract]
public interface INFCReader
{
    [OperationContract]
    [WebInvoke(UriTemplate = "GetLogin", Method = "POST")]
    GetLoginResults GetLogin(DisplayRequest dispRequest);
}

这里 DisplayRequest 是一个类。

请帮助各位。让我知道是否有人想查看任何其他代码。

非常感谢。

编辑：：：：：：：

非常感谢托马斯的回复。我创建了一个实现 IDispactchMessageInspector 的类 MessageInspector。我在 MessageInspector 类中有以下代码。

public class MessageInspector : IDispatchMessageInspector
{
    public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
    {
        HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "*");
        if (HttpContext.Current.Request.HttpMethod == "OPTIONS")
        {
            HttpContext.Current.Response.AddHeader("Cache-Control", "no-cache");
            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Methods", "GET, POST");
            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Headers", "Content-Type, Accept");
            HttpContext.Current.Response.AddHeader("Access-Control-Max-Age", "1728000");
            HttpContext.Current.Response.End();
        }
        return null;
    }
}

我现在得到的错误是——“对象引用未设置为对象的实例。” 错误在上述代码的这一行

HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "*");

我要做的就是为我的 Web 服务添加 CORS 支持。如果我做得正确，请告诉我。或者有没有其他方法可以做到这一点。

4

2 回答 2

17

终于找到了我的查询的解决方案。

都在这里。支持跨域资源

很好的一步一步的解释。我想我自己永远也想不通。

代码：

创建 2 个类，如下所示：

  1. MessageInspector实施IDispatchMessageInspector.
  2. BehaviorAttribute实施Attribute,IEndpointBehavior和IOperationBehavior.

带有以下详细信息：

//MessageInspector Class
using System;
using System.ServiceModel;
using System.ServiceModel.Channels;
using System.ServiceModel.Dispatcher;
using System.ServiceModel.Description;
namespace myCorsService
{
  public class MessageInspector  : IDispatchMessageInspector
  {
    private ServiceEndpoint _serviceEndpoint;

    public MessageInspector(ServiceEndpoint serviceEndpoint)
    {
      _serviceEndpoint = serviceEndpoint;
    }

    /// <summary>
    /// Called when an inbound message been received
    /// </summary>
    /// <param name="request">The request message.</param>
    /// <param name="channel">The incoming channel.</param>
    /// <param name="instanceContext">The current service instance.</param>
    /// <returns>
    /// The object used to correlate stateMsg. 
    /// This object is passed back in the method.
    /// </returns>
    public object AfterReceiveRequest(ref Message request, 
                                          IClientChannel channel, 
                                          InstanceContext instanceContext)
    {
      StateMessage stateMsg = null;
      HttpRequestMessageProperty requestProperty = null;
      if (request.Properties.ContainsKey(HttpRequestMessageProperty.Name))
      {
        requestProperty = request.Properties[HttpRequestMessageProperty.Name]
                          as HttpRequestMessageProperty;
      }

      if (requestProperty != null)
      {
        var origin = requestProperty.Headers["Origin"];
        if (!string.IsNullOrEmpty(origin))
        {
          stateMsg = new StateMessage();
          // if a cors options request (preflight) is detected, 
          // we create our own reply message and don't invoke any 
          // operation at all.
          if (requestProperty.Method == "OPTIONS")
          {
            stateMsg.Message = Message.CreateMessage(request.Version, null);
          }
          request.Properties.Add("CrossOriginResourceSharingState", stateMsg);
        }
      }

      return stateMsg;
    }

    /// <summary>
    /// Called after the operation has returned but before the reply message
    /// is sent.
    /// </summary>
    /// <param name="reply">The reply message. This value is null if the 
    /// operation is one way.</param>
    /// <param name="correlationState">The correlation object returned from
    ///  the method.</param>
    public void BeforeSendReply(ref  Message reply, object correlationState)
    {
      var stateMsg = correlationState as StateMessage;

      if (stateMsg != null)
      {
        if (stateMsg.Message != null)
        {
          reply = stateMsg.Message;
        }

        HttpResponseMessageProperty responseProperty = null;

        if (reply.Properties.ContainsKey(HttpResponseMessageProperty.Name))
        {
          responseProperty = reply.Properties[HttpResponseMessageProperty.Name]
                             as HttpResponseMessageProperty;
        }

        if (responseProperty == null)
        {
          responseProperty = new HttpResponseMessageProperty();
          reply.Properties.Add(HttpResponseMessageProperty.Name,
                               responseProperty);
        }

        // Access-Control-Allow-Origin should be added for all cors responses
        responseProperty.Headers.Set("Access-Control-Allow-Origin", "*");

        if (stateMsg.Message != null)
        {
          // the following headers should only be added for OPTIONS requests
          responseProperty.Headers.Set("Access-Control-Allow-Methods",
                                       "POST, OPTIONS, GET");
          responseProperty.Headers.Set("Access-Control-Allow-Headers",
                    "Content-Type, Accept, Authorization, x-requested-with");
        }
      }
    }
  }

  class StateMessage
  {
    public Message Message;
  }
}

//BehaviorAttribute Class
using System;
using System.ServiceModel.Channels;
using System.ServiceModel.Description;
using System.ServiceModel.Dispatcher;

namespace OpenBetRetail.NFCReaderService
{
  public class BehaviorAttribute : Attribute, IEndpointBehavior,
                                 IOperationBehavior
  {        
    public void Validate(ServiceEndpoint endpoint) { }

    public void AddBindingParameters(ServiceEndpoint endpoint,
                             BindingParameterCollection bindingParameters) { }

    /// <summary>
    /// This service modify or extend the service across an endpoint.
    /// </summary>
    /// <param name="endpoint">The endpoint that exposes the contract.</param>
    /// <param name="endpointDispatcher">The endpoint dispatcher to be
    /// modified or extended.</param>
    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, 
                                      EndpointDispatcher endpointDispatcher)
    {
      // add inspector which detects cross origin requests
      endpointDispatcher.DispatchRuntime.MessageInspectors.Add(
                                             new MessageInspector(endpoint));
    }

   public void ApplyClientBehavior(ServiceEndpoint endpoint,
                                   ClientRuntime clientRuntime) { }

   public void Validate(OperationDescription operationDescription) { }

   public void ApplyDispatchBehavior(OperationDescription operationDescription,
                                     DispatchOperation dispatchOperation) { }

   public void ApplyClientBehavior(OperationDescription operationDescription,
                                   ClientOperation clientOperation) { }

   public void AddBindingParameters(OperationDescription operationDescription,
                             BindingParameterCollection bindingParameters) { }

  }
}

在此之后，您需要做的就是将此消息检查器添加到服务端点行为。

ServiceHost host = new ServiceHost(typeof(myService), _baseAddress);
foreach (ServiceEndpoint EP in host.Description.Endpoints)
            EP.Behaviors.Add(new BehaviorAttribute());

谢谢大家帮助。

于 2013-04-16T14:38:39.663 回答
1

我相信在 WCF 世界中最接近Application_BeginRequest的是Message Inspectors：

消息检查器是一个可扩展性对象，可以在服务模型的客户端运行时中使用，并以编程方式或通过配置调度运行时，并且可以在收到消息之后或发送消息之前检查和更改消息。

为了使用自定义消息检查器，您必须：

  1. 创建一个实现IDispatchMessageInspector接口的类（您的自定义检查器）
  2. 将自定义检查器添加到服务的DispatchRuntime.MessageInspectors集合

在这里，您可以找到有关如何执行此操作的更多信息和一些示例代码。

于 2013-04-16T01:33:15.120 回答