WCF Tenets

There are four tenets of WCF:

1. Service boundaries are explicit
In WCF, we must need to expose the service contract to client so client can consume the service and call service method. If we will expose the implemented class then it will mess the boundaries of your service.
2. Service are autonomous
Service must be give full information about itself to client who wants to consume it like address where service is available, which message format service is expected, what transport service is using to receive messages etc.
3. Share Schema not the implementation
Expose only service contract (interface) to client. Never share implemented code to client. It will be very difficult to manage the changes if we will share code with the clients. We need to change code to every place if any change needs into service code.
4. Service Compatibility is Policy based
Service compatibility must be policy based so whenever Admin user will change any policy developer does not required to change accordingly.