signalr 配置错误跟踪

<system.diagnostics>
  <trace autoflush="true" indentsize="4">
    <listeners>
      <add name="default_traces" type="System.Diagnostics.TextWriterTraceListener" initializeData="default_traces.txt" />
    </listeners>
  </trace>
  <switches>
    <add name="SignalRSwitch" value="Error" />
  </switches>
  <sources>

    <source name="Application">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>

    <source name="Microsoft.Owin.Host.SystemWeb">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>

    <source name="SignalR.SqlMessageBus">
      <listeners>
        <add name="SignalR-Bus" />
      </listeners>
    </source>
    <source name="SignalR.ServiceBusMessageBus">
      <listeners>
        <add name="SignalR-Bus" />
      </listeners>
    </source>
    <source name="SignalR.RedisMessageBus">
      <listeners>
        <add name="SignalR-Bus" />
      </listeners>
    </source>
    <source name="SignalR.ScaleoutMessageBus">
      <listeners>
        <add name="SignalR-Bus" />
      </listeners>
    </source>

    <source name="SignalR.Connection">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.PersistentConnection">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.HubDispatcher">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.Transports.WebSocketTransport">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.Transports.ServerSentEventsTransport">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.Transports.ForeverFrameTransport">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.Transports.LongPollingTransport">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.Transports.TransportHeartBeat">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
    <source name="SignalR.ReflectedHubDescriptorProvider">
      <listeners>
        <add name="traces" />
      </listeners>
    </source>
  </sources>
  <sharedListeners>
    <add name="traces" type="System.Diagnostics.TextWriterTraceListener" initializeData="server_traces.txt" />
  </sharedListeners>
</system.diagnostics>