Url registration issue with WCF when Http binding is used

Question

I'm trying to host two WCF services in one application. I want them to share the same BaseAddress but have their own URLs something like: net.tcp://localhost:1234/service1 and net.tcp://localhost:1234/service2

The following config allows me to do that:

<system.serviceModel>
    <services>
        <service name="VanillaWcf.Shared.MyService" behaviorConfiguration="beh">
            <endpoint address="myservice" binding="netTcpBinding" name="tcpEndPoint" contract="VanillaWcf.Shared.IMyService" />
            <endpoint address="myservice" binding="wsHttpBinding" name="httpEndPoint" contract="VanillaWcf.Shared.IMyService"/>
            <host>
                <baseAddresses>
                    <add baseAddress="net.tcp://localhost:1234" />
                </baseAddresses>
            </host>
        </service>
        <service name="VanillaWcf.Shared.SecondService" behaviorConfiguration="beh">
            <endpoint address="secondService" binding="netTcpBinding" name="tcpEndPoint" contract="VanillaWcf.Shared.ISecondService"/>
            <endpoint address="secondService" binding="wsHttpBinding" name="httpEndPoint" contract="VanillaWcf.Shared.ISecondService"/>
            <host>
                <baseAddresses>
                    <add baseAddress="net.tcp://localhost:1234"/>
                </baseAddresses>
            </host>
        </service>
    </services>
    <behaviors>
        <serviceBehaviors>
            <behavior name="beh">
                <serviceMetadata httpGetEnabled="false"/>
            </behavior>
        </serviceBehaviors>
    </behaviors>
</system.serviceModel>

And the code is:

        ServiceHost host = new ServiceHost(typeof(MyService));
        ServiceHost secondHost = new ServiceHost(typeof(SecondService));

        host.Open();
        secondHost.Open();

This works fine.

However, I get an exception when I add http://localhost:4321 as the base address of both services in the config.

The exception is: The ChannelDispatcher at 'http://localhost:4321/' with contract(s) '"IHttpGetHelpPageAndMetadataContract"' is unable to open its IChannelListene' with an inner exception of A registration already exists for URI 'http://localhost:4321

I don't have any MEX configuration and I don't want it.

Note: My NetPortSharing service is disabled.

Answer 1

You can't have two base address with the same scheme (net.tcp) and the same address - you'll have to change something.

One possibility might be to not use base addresses, but completely specify the net.tcp addresses on your two endpoints. This might work (should, because the whole address is different for the two services).

<service name="VanillaWcf.Shared.MyService" behaviorConfiguration="beh">
   <endpoint name="tcpEndPoint" 
       address="net.tcp://localhost:1234/myservice1" 
       binding="netTcpBinding" 
       contract="VanillaWcf.Shared.IMyService" />
</service>

Marc

Answer 2

Port sharing is possible, but you need to configure things correctly.

See http://msdn.microsoft.com/en-us/library/ms734772.aspx

Answer 3

In general only one application can listen on a tcp port at a time.

For net.tcp MS has done some work to allow port sharing. See:

http://technet.microsoft.com/en-us/library/cc753154.aspx

But this is specific to the net.tcp binding. You therefore get a problem when you try to listen for http on the same port.

Answer 4

I found the answer, but can't figure out why! It turns out when using net.tcp the same base address can be used with different service addresses i.e. net.tcp://localhost:1234 as the base address and /service1 and /service2.

However, when using http the full URL should be specified at the service level: i.e. Leave base address blank and use http://localhost:4321/service1 and http://localhost:4321/service2 at the service level.

This seems a big inconsistent with the whole idea of decoupling protocol from configuration which WCF puts a lot of emphasis upon, but it seems to be the case.