Use case diagram legend
Each use case has a Universal Modeling Language (UML) robustness diagram associated with it. A robustness diagram depicts the core components of a system and how the components communicate or collaborate with one another to satisfy a use case. Arrows between the components indicate the flow of information between the components.
The following symbols are used:
Actor — User role that interacts with a component in the system
Boundary — Component that represents an interface with which Actors interact
Entity — Domain objects within the system that typically present a persisted state of that object
Control — Components that connect Boundary and Entity components and implement some logic to manage the interaction between them