我面临的问题是，客户端在第二次启动时无法注册回调通道。我尝试了各种方法，似乎找到了一个解决方案，就是在服务关闭时删除Close()通道(在包装器中调用ResetProxy())。但是这导致了另一个问题：服务器崩溃并出现错误 "线程试图从一个虚拟地址读取或写入它没有适当的访问权限"此外，还有一些网络相关的问题，也会导致同样的行为。解决方法总是重启服务器，这并不是解决回调通道注册的真正正确选择.有谁能建议可能是什么问题？我做了很多测试，似乎这与所有客户端的突然停止有关（多个服务的全局停止），服务的数量也很重要。结果在服务器重启之前，即使是新的客户端也无法在服务器上注册。这听起来像是服务器把通道封闭了。
合同。
[ServiceContract(SessionMode = SessionMode.Required, CallbackContract = typeof(IAgentCallback))]
public interface IAgentManager
{
[OperationContract]
string RegisterAgent(string hostName);
[OperationContract]
bool Ping();
}
客户端创建回调代码(截断):
public class AgentCallbackDaemon
{
private void CreateManagerProxy()
{
Reset();
var isUnbound = true;
while (isUnbound)
{
try
{
ManagerProxy = new ProxyWrapper<AgentManagerProxy, IAgentManager>(CreateProxy);
ManagerProxy.ChannelStateChanged += HandleProxyConnectionStateChanged;
isUnbound = false;
}
catch (AddressAlreadyInUseException)
{
sLog.ErrorFormat("Port is already reserved, binding failed.");
}
catch (Exception error)
{
sLog.ErrorFormat($"No proxy due to {error}");
throw;
}
}
}
private AgentManagerProxy CreateProxy()
=> mCallbackChannelPortRange.IsCallbackPortRageSet() ? GetProxyWithPortRange() : GetProxyDefault();
private AgentManagerProxy GetProxyDefault()
=> new AgentManagerProxy(mAgentCallback, mManagerUri, GetServiceName());
private AgentManagerProxy GetProxyWithPortRange()
{
var minPort = mCallbackChannelPortRange.MinimumCallbackPortNumber;
var maxPort = mCallbackChannelPortRange.MaximumCallbackPortNumber;
return new AgentManagerProxy(mAgentCallback, mManagerUri, GetServiceName(), minPort, maxPort);
}
}
客户端回调代码（截断）：
public class AgentManagerProxy : DuplexClientBase<IAgentManager>, IAgentManager
{
public const string SERVICE_NAME = "AgentManager";
public AgentManagerProxy(IAgentCallback callback, string serviceAddress, string connectionId,
ushort minPort, ushort maxPort)
: base(callback, BindingAbstractFactory.DuplexServiceClientBindingFactory(connectionId,
minPort, maxPort), BindingUtility.CreateEndpoint(serviceAddress, SERVICE_NAME))
{
}
public string RegisterAgent(string hostName)
=> Channel.RegisterAgent(hostName);
public bool Ping() => return Channel.Ping();
}
public static class BindingAbstractFactory
{
public static Binding DuplexServiceClientBindingFactory(string connectionId, ushort minPort, ushort maxPort)
=> CreateDuplexServiceClientBinding(connectionId, minPort, maxPort);
private static Binding CreateDuplexServiceClientBinding(string connectionId, ushort minPort, ushort maxPort)
{
var binding = CreateDuplexServiceHostBinding();
if (binding is WSDualHttpBinding)
{
lock (sLock)
{
try
{
((WSDualHttpBinding)binding).ClientBaseAddress =
CreateClientBaseAddress(connectionId, minPort, maxPort);
}
catch (Exception error)
{
sLog.ErrorFormat("Unexpected exception: {0}", error);
throw error;
}
finally
{
Monitor.PulseAll(sLock);
}
}
}
return binding;
}
private static Binding CreateDuplexServiceHostBinding()
{
var binding = new WSDualHttpBinding
{
ReceiveTimeout = TimeSpan.MaxValue,
MaxReceivedMessageSize = int.MaxValue,
ReaderQuotas =
{
// Set the maximum sizes to allow big message sizes.
MaxArrayLength = int.MaxValue,
MaxBytesPerRead = int.MaxValue,
MaxDepth = int.MaxValue,
MaxNameTableCharCount = int.MaxValue,
MaxStringContentLength = int.MaxValue
},
Security =
{
// Disable security on control services.
// TODO: Once security concept has been clarified, update this to reflect security rules.
Mode = WSDualHttpSecurityMode.None,
Message = { ClientCredentialType = MessageCredentialType.None }
//// binding.Security.Mode = SecurityMode.None;
//// binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None;
}
};
return binding;
}
private static Uri CreateClientBaseAddress(string connectionId, ushort minPort, ushort maxPort)
{
var fullDnsName = Dns.GetHostEntry(Dns.GetHostName()).HostName;
int portNumber;
if (maxPort == ushort.MaxValue)
portNumber = LocalPorts.GetRandomAvailablePort(connectionId, minPort, maxPort);
else
portNumber = LocalPorts.GetNextAvailablePort(connectionId, minPort, maxPort);
return new Uri($@"http://{fullDnsName}:{portNumber}");
}
}
所有这些都被封装到代理封装器中，并带有Reset函数，该函数在服务停止或任何错误（包括网络）时被调用。
public class ProxyWrapper<TPROXY, TSERVICE> where TPROXY : ClientBase<TSERVICE> where TSERVICE : class
{
public delegate TPROXY CreateProxy();
private readonly object mProxyLock = new object();</summary>
private readonly CreateProxy mCreateProxy;
private TPROXY mProxy;
public ProxyWrapper(CreateProxy createProxyCallback)
{
mLog.Info.Write($"Creating Proxy for '{typeof(TPROXY).FullName}'");
mCreateProxy = createProxyCallback;
BuildProxy();
}
public event EventHandler<CommunicationState> ChannelStateChanged;
public TPROXY Proxy
{
get
{
lock (mProxyLock)
{
if (mProxy == null)
BuildProxy();
return mProxy;
}
}
}
public void ResetProxy()
{
mLog.Info.Write("Call ResetProxy()");
lock (mProxyLock)
{
try
{
if (mProxy == null)
return;
UnSubscribeFromChannelEvents();
CloseProxy();
}
catch (Exception ex)
{
// Catch all exceptions, and ignore them.
}
finally
{
mProxy = null;
}
}
}
private void RaiseChannelStateChanged(object sender, EventArgs e)
=> ChannelStateChanged?.Invoke(this, mProxy.InnerChannel.State);
private void RaiseChannelEnteredFaultyState()
=> ChannelStateChanged?.Invoke(this, CommunicationState.Faulted);
private void BuildProxy()
{
lock (mProxyLock)
{
if (mProxy != null)
ResetProxy();
mProxy = mCreateProxy();
SubscribeToChannelEvents();
}
}
private void SubscribeToChannelEvents()
{
if (mProxy?.InnerChannel == null)
return;
mProxy.InnerChannel.Faulted += OnInnerChannelFaulted;
mProxy.InnerChannel.Closed += RaiseChannelStateChanged;
mProxy.InnerChannel.Closing += RaiseChannelStateChanged;
mProxy.InnerChannel.Opened += RaiseChannelStateChanged;
mProxy.InnerChannel.Opening += RaiseChannelStateChanged;
}
private void UnSubscribeFromChannelEvents()
{
if (mProxy?.InnerChannel == null)
return;
mProxy.InnerChannel.Faulted -= OnInnerChannelFaulted;
mProxy.InnerChannel.Closed -= RaiseChannelStateChanged;
mProxy.InnerChannel.Closing -= RaiseChannelStateChanged;
mProxy.InnerChannel.Opened -= RaiseChannelStateChanged;
mProxy.InnerChannel.Opening -= RaiseChannelStateChanged;
}
private void OnInnerChannelFaulted(object sender, EventArgs e)
{
ResetProxy();
RaiseChannelEnteredFaultyState();
}
private void CloseProxy()
{
try
{
mProxy.Close();
}
catch (Exception ex)
{
try
{
mProxy.Abort();
}
catch (Exception abortException) { // ignored }
}
try
{
mProxy.ChannelFactory.Close();
}
catch (Exception ex)
{
try
{
mProxy.ChannelFactory.Abort();
}
catch (Exception abortException) { // ignored }
}
}
}
服务器只维护回调列表。
增加了客户端的日志记录，第一次启动时就会显示。
第二次启动时服务失败。
错误，由于System.TimeoutException: No proxy due to System.TimeoutException: No proxy由于System.TimeoutException，没有代理。请求通道在00:00:00之后尝试发送时超时了。增加传递给调用Request的超时值，或者增加Binding上的SendTimeout值。分配给该操作的时间可能是较长超时的一部分。---> System.TimeoutException: 对''的HTTP请求。http:/xxxxx:9003AgentManager。'已经超过了分配的00:00:00超时时间。分配给这个操作的时间可能是一个较长的超时的一部分。 在System.ServiceModel.Channels.HttpChannelUtilities.SetRequestTimeout(HttpWebRequest request, TimeSpan timeout) 在System.ServiceModel.Channels.
你的客户端数量可能超过了Maxconcurrentinstances的值.Maxconcurrentinstances是一个正整数，它限制了一次可以通过ServiceHost执行的实例context对象的数量。当槽数低于限制时，创建其他实例的请求会被排队并完成。默认值是maxconcurrentsessions和maxconcurrentcalls的总和.你需要在每个客户端完成后关闭通道.否则，在客户端长时间排队后会出现异常。
try
{
if (client.State != System.ServiceModel.CommunicationState.Faulted)
{
client.Close();
}
}
catch (Exception ex)
{
client.Abort();
}
关闭方法可能会失败。如果关闭方法失败，需要使用abort方法。