Allow only a single client at a time

Question

I'm on the WCF coding now, and the question is quite standard:

I need my WCF server to manage a hardware device, so I critically need only 1 client allowed at a time. I did try some solutions found at the site, but neither

[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single,
                 ConcurrencyMode = ConcurrencyMode.Multiple)]

nor the addition of

<behavior name="Throttled">
     <serviceThrottling maxConcurrentCalls="1"
     maxConcurrentSessions="1"
     maxConcurrentInstances="1" />
</behavior>

doesn't block me from running a 2nd application and ruining the server.

Should I learn more about client authentication or there is a magic line I can add to solve this part?

Answer 1

As I mentioned before, all those actions are not sufficient. Looks like the key is to maintain a WCF session mode - so, I added [ServiceContract (SessionMode = SessionMode.Required)] with wsHttpBinding instead of basicHttpBinding (which is not allowed to maintain a session). Now it works.