WCF Singleton services: single instance per what? Per host instance?

Question

My understanding is that for a WCF service with Single instance mode, the "single" is only true per host instance, i.e. it's quite possible to have multiple host instances (in the same process?) with different endpoint URLs and different service instances in each, and their state will remain separate. Is this correct?

Answer 1

Yes, it is possible to have many service hosts per process. And yes, singleton means one WCF service instance per service host.