如何在System.ServiceModel.ChannelFactory中优化WCF CreateFactory？

Question

我当前的实现是利用ClientBase类为第三方API的WCF调用创建一个通道.此第三方API需要对X509Certificate2证书以及ClientCredentials进行身份验证.

public class HeaderAdder : ContextBoundObject, IClientMessageInspector
{
    public bool RequestFailedDueToAuthentication;

    public string UserName { get; set; }
    public string Password { get; set; }

    public object BeforeSendRequest(ref Message request, IClientChannel channel)
    {
        var property = new UserNameHeader
        {
            Password = Password,
            UserName = UserName
        };
        request.Headers.Add(MessageHeader.CreateHeader("UserNameHeader", "test", property));
        return null;
    }

    public void AfterReceiveReply(ref Message reply, object correlationState)
    {
        RequestFailedDueToAuthentication = reply.ToString().Contains("ErrorCode>-4<");
    }
}

public class CustomEndpointBehavior : IEndpointBehavior
{
    private readonly HeaderAdder _headerAdder;

    public CustomEndpointBehavior(HeaderAdder headerAdder)
    {
        _headerAdder = headerAdder;
    }

    public void Validate(ServiceEndpoint endpoint)
    {
        //throw new NotImplementedException();
    }

    public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
    {
        //throw new NotImplementedException();
    }

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
    {
        //throw new NotImplementedException();
    }

    public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
    {
        var credentials = endpoint.Behaviors.Find<ClientCredentials>();
        if (!string.IsNullOrEmpty(credentials.UserName.Password))
        {
            _headerAdder.UserName = credentials.UserName.UserName;
            _headerAdder.Password = credentials.UserName.Password;
            clientRuntime.ClientMessageInspectors.Add(_headerAdder);
        }
    }
}

客户端实例化和请求可以在这里看到:

var client = new TestClient()
{
    ClientCredentials =
    {
        UserName =
        {
            UserName = "testing",
            Password = "testing"
        },
        UseIdentityConfiguration = true
    }
};
client.ClientCredentials?.ClientCertificate.SetCertificate(
    StoreLocation.LocalMachine, 
    StoreName.My,
    X509FindType.FindByIssuerName, 
    "Testing");
client.ChannelFactory.Endpoint.EndpointBehaviors.Add(
   new CustomEndpointBehavior(new HeaderAdder()));
var request = new Request();
client.Get(request);

不幸的是,为WCF调用创建Channel的过程需要9秒以上才能完成.使用ReSharper的doTrace探查器,我能够看到代码在以下方法上被阻止:System.ServiceModel.Description.XmlSerializer.OperationBehavior + Reflecto.EnsureMessageInfos

可以在下面看到在System.ServiceModel中进行的调用的完整堆栈跟踪.

System.ServiceModel.ClientBase`1.get_Channel
System.ServiceModel.ClientBase`1.CreateChannelInternal
System.ServiceModel.ClientBase`1.CreateChannel
System.ServiceModel.ChannelFactory`1.CreateChannel
System.ServiceModel.ChannelFactory`1.CreateChannel(EndpointAddress, Uri)
System.ServiceModel.ChannelFactory.EnsureOpened
System.ServiceModel.Channels.CommunicationObject.Open(TimeSpan)
System.ServiceModel.ChannelFactory.OnOpening
System.ServiceModel.ChannelFactory.CreateFactory
System.ServiceModel.Channels.ServiceChannelFactory.BuildChannelFactory(ServiceEndpoint, Boolean)
System.ServiceModel.Description.DispatcherBuilder.BuildProxyBehavior(ServiceEndpoint, out BindingParameterCollection)
System.ServiceModel.Description.DispatcherBuilder.ApplyClientBehavior(ServiceEndpoint, ClientRuntime)
System.ServiceModel.Description.DispatcherBuilder.BindOperations(ContractDescription, ClientRuntime, DispatchRuntime)
System.ServiceModel.Description.XmlSerializerOperationBehavior.ApplyClientBehavior(OperationDescription, ClientOperation)
System.ServiceModel.Description.XmlSerializerOperationBehavior.CreateFormatter
System.ServiceModel.Description.XmlSerializerOperationBehavior+Reflector.EnsureMessageInfos

我已经尝试使用sgen.exe来创建XML序列化程序集,希望它能提高序列化程序的性能.不幸的是,它没有任何效果.

我还在网上找到了几种建议缓存渠道或渠道工厂的方法,例如http://www.itprotoday.com/microsoft-visual-studio/wcf-proxies-cache-or-not-cache.但是,这些方法不适用于此实现,因为Channel Factory具有与之关联的客户端凭据.这将需要为每个客户端缓存一个Channel Factory或Channel,这是不现实的.

有没有人知道一种方法可以防止ChannelFactory在创建时反映出Request和Response对象？任何人都可以在这个问题上提供的任何帮助将非常感谢.

Answer 1

我不知道有什么机制可以让您绕过您在这里看到的行为。这本质上就是ChannelFactory设计的：它承担了反射和组合通道堆栈的一次性沉重成本，为您提供了一个廉价的例程来创建通道实例。如果你想节省 9 秒，你必须重新使用工厂。

通常我建议使用与客户端实例关联的内置缓存ChannelFactory，但在您触摸该属性时这会失效ClientCredentials。

我建议您确实需要考虑ChannelFactory在每个客户端的基础上缓存每个内容。除非您拥有数万组凭据，否则这并不是一个不切实际的前景。事实上，这就是 .NET 中的 HTTP 系统预授权请求的方式。