Operations

In classic object or component- oriented programming model offered only single way for client to call a method. Client will issue a call, block while the call was in progress, and continue executing once the method returned.
WCF will support classical Request-Replay model, along with that it also supports One-Way call(call and forget operation) and callback(service to call back the client)
Three modes of communication between client and service are

1. Request- Replay
2. One-Way
3. Callback