When services act in a manner that serves a business purpose which results in a business process being completed, it's known as service orchestration. It directly addresses the implementation of business process implementation. It actually binds business logic and data exchange between applications together so that the desired flow is met.
From another point of view, it can also be said that service orchestration arranges services so that they look like a single service meant to complete a single flow.
To achieve service orchestration, every service involved in orchestration shares data among themselves where sometimes an output of one service acts as an input to the other.
But it should be noted that individual services are not designed to communicate with each other, messages should be exchanged based on certain business rules and execution sequence. To provide communication between all applications in SOA we have the concept of Enterprise Application Integration (EAI...