BTownTKD BTownTKD - 1 month ago 18
C# Question

WCF NamedPipe CommunicationException - "The pipe has been ended. (109, 0x6d)."

I am writing a Windows Service with accompanying "status tool." The service hosts a WCF named pipe endpoint for inter-process communication. Through the named pipe, the status tool can periodically query the service for the latest "status."

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On my development machine, I have multiple IP Addresses; one of them is a "local" network with a 192.168.1.XX address. The other is the "corporate" network, with a 10.0.X.XX address. The Windows Service collects UDP multicast traffic on a single IP Address.

The Windows Service has, until now, worked fine as long as it uses the "192.168.1.XX," address. It consistently reports the status correctly to the client.

As soon as I switched to the other, "corporate" IP Address (10.0.X.XX) and restarted the service, I get continuous "CommunicationExceptions" when retrieving the status:

"There was an error reading from the pipe: The pipe has been ended. (109, 0x6d)."


Now, I wouldn't think that the UDP Client's 'claimed' IP address should have anything to do with the functionality of the Named-Pipe interface; they are completely separate pieces of the application!

Here are the relevant WCF config sections:

//On the Client app:
string myNamedPipe = "net.pipe://127.0.0.1/MyNamedPipe";
ChannelFactory<IMyService> proxyFactory =
new ChannelFactory<IMyService>(
new NetNamedPipeBinding(),
new EndpointAddress(myNamedPipe));


//On the Windows Service:
string myNamedPipe = "net.pipe://127.0.0.1/MyNamedPipe";
myService = new MyService(myCustomArgs);
serviceContractHost = new ServiceHost(myService );
serviceContractHost.AddServiceEndpoint(
typeof(IMyService),
new NetNamedPipeBinding(),
myNamedPipe);

serviceContractHost.Open();


I wouldn't think this is a 'permissions' issue - I'm running the client with administrative privileges - but perhaps there's some domain-specific reason this broke?

Answer

The IP Address was, it turns out, a complete red herring.

The real reason for the exception was invalid Enum values being returned by the WCF service.

My enum was defined thusly:

[DataContract]
public enum MyEnumValues : Byte
{
    [EnumMember]
    Enum1 = 0x10,
    [EnumMember]
    Enum2 = 0x20,
    [EnumMember]
    Enum3 = 0x30,
    [EnumMember]
    Enum4 = 0x40,
} 

It looks fine on the surface.

But the raw status reported by the underlying service was a Byte value of "0," and there was no corresponding Enum value for which to cast it.

Once I ensured that the Enum values were all valid, the tool lit up like a Christmas tree.

When in doubt, assume your WCF data is invalid.

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