This is a UML sequence diagram example for MVC design pattern.
- Entities are objects representing system data: Customer, Product, Transaction, Cart, etc.
- Boundaries are objects that interface with system actors: UserInterface, DataBaseGateway, ServerProxy, etc.
- Controls are objects that mediate between boundaries and entities.
They orchestrate the execution of commands coming from the boundary by interacting with entity and boundary objects. Controls often correspond to use cases scenario and often represented by a sequence diagram.