c# - 使用 net.tcp ://0. 0.0.0 :0/blah announces net. tcp ://0. 0.0.0:0/blah 使用服务主机发现 WCF

Question

我想要一个可以监听所有接口(interface)并为每个接口(interface)发布发现公告的可发现服务。我希望最终能够使用 tcp://0.0.0.0:0/blah 作为服务端点在配置文件中配置它。但是当我运行下面的代码时，它发出的公告使用 tcp://0.0.0.0:0/blah 作为对客户端无用的 EndpointAddress。

我想收到来自 tcp://0.0.0.0:0/blah 的每个端点的公告，我更愿意使用配置文件而不是如下所示的程序化服务主机设置。任何解决方法的想法？

    [TestFixtureSetUp]
    public void SetUp()
    {
        service1 = new MyContract();
        EndpointDiscoveryBehavior discoveryBehavior = new EndpointDiscoveryBehavior();
        ServiceDiscoveryBehavior serviceDiscoveryBehavior = new ServiceDiscoveryBehavior(discoveryUri);
        serviceDiscoveryBehavior.AnnouncementEndpoints.Add(new UdpAnnouncementEndpoint(announcementUri));

        serviceHost1 = new ServiceHost(service1,
            new Uri[] {new Uri("net.pipe://localhost"), new Uri("net.tcp://0.0.0.0:0")});
        ServiceEndpoint localEndpoint1 = serviceHost1.AddServiceEndpoint(typeof (IContract),
            new NetNamedPipeBinding(),
            "/Pipe");
        ServiceEndpoint localEndpoint2 = serviceHost1.AddServiceEndpoint(typeof (IContract),
            new NetTcpBinding(),
            "/Tcp");
        localEndpoint2.Behaviors.Add(discoveryBehavior);
        serviceHost1.Description.Behaviors.Add(serviceDiscoveryBehavior);
        serviceHost1.AddServiceEndpoint(new UdpDiscoveryEndpoint(discoveryUri));

        serviceHost1.Open();
    }

Answer 1

虽然我的解决方案可能不“正确”，但严格来说(如果您问我，这实际上应该在 WCF 本身中修复)，但它有效，并且足以满足我的目的。

首先，声明一个新的端点行为，如下所示:

public class WcfDiscoveryAddressFixEndpointBehavior : IEndpointBehavior, IDispatchMessageInspector
{
    public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
    {
        // Attach ourselves to the MessageInspectors of reply messages
        clientRuntime.CallbackDispatchRuntime.MessageInspectors.Add(this);
    }

    public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
    {
        object messageProperty;
        if (!OperationContext.Current.IncomingMessageProperties.TryGetValue(RemoteEndpointMessageProperty.Name, out messageProperty)) return null;
        var remoteEndpointProperty = messageProperty as RemoteEndpointMessageProperty;
        if (remoteEndpointProperty == null) return null;

        // Extract message body
        string messageBody;
        using (var oldMessageStream = new MemoryStream())
        {
            using (var xw = XmlWriter.Create(oldMessageStream))
            {
                request.WriteMessage(xw);
                xw.Flush();
                messageBody = Encoding.UTF8.GetString(oldMessageStream.ToArray());
            }
        }

        // Replace instances of 0.0.0.0 with actual remote endpoint address
        messageBody = messageBody.Replace("0.0.0.0", remoteEndpointProperty.Address);

        // NOTE: Do not close or dispose of this MemoryStream. It will be used by WCF down the line.
        var newMessageStream = new MemoryStream(Encoding.UTF8.GetBytes(messageBody));
        XmlDictionaryReader xdr = XmlDictionaryReader.CreateTextReader(newMessageStream, new XmlDictionaryReaderQuotas());

        // Create a new message with our modified endpoint address and
        // copy over existing properties and headers
        Message newMessage = Message.CreateMessage(xdr, int.MaxValue, request.Version);
        newMessage.Properties.CopyProperties(request.Properties);
        newMessage.Headers.CopyHeadersFrom(request.Headers);
        request = newMessage;
        return null;
    }

    public void BeforeSendReply(ref Message reply, object correlationState)
    {
    }

    public void Validate(ServiceEndpoint endpoint)
    {
    }

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

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
    {
    }
}

此端点行为将原始 WCF 发现回复消息替换为副本，其中 0.0.0.0 的实例已替换为接收消息的地址，可在 RemoteEndpointMessageProperty< 中获得 的 Address 属性。

要使用它，只需在创建 DiscoveryClient 时将新端点行为添加到 UdpDiscoveryEndpoint:

var udpDiscoveryEndpoint = new UdpDiscoveryEndpoint();
udpDiscoveryEndpoint.EndpointBehaviors.Add(new WcfDiscoveryAddressFixEndpointBehavior());
_discoveryClient = new DiscoveryClient(udpDiscoveryEndpoint);

// Proceed as usual.