WCF Multiple Apps using NetNamedPipe

Question

I am trying to run multiple WCF Service hosting apps on the same Machine.

I want to run multiple Applications - not multiple services in one application

Answer 1

Approaching it like this will do what you want, I believe:

string relativeUriPart = GetUniquePartFromConfigOfThisApplicationInstance();
var host = new ServiceHost(typeof(MyClass1)); // No base addresses specified
host.AddServiceEndpoint(
    typeof(ISomeInterface),  
    new NetNamedPipeBinding(), 
    "net.pipe://localhost/" + relativeUriPart); // Specify absolute URI for endpoint
host.Open();

This is because, if you specify a base address which uses the net.pipe scheme, it is this base address which is used to derive the pipe name used by the listener [see edit below], and this is the same in each application instance, so only the first application's listener can create the pipe - the others fail as you have noted.

Using the absolute URI at the endpoint level, with no base address, the listener is created with a pipe name derived [see edit below] from the full absolute URI, which is different in each application instance, and so each application's listener can create its own distinct pipe without any problem.

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EDIT: To be more precise, the pipe name itself is not derived from the service address at all - it is a GUID which changes each time the service is opened. What is derived from the service address is the name of a shared memory object via which the actual name of the pipe is published to prospective clients. See here for more details.