A protocol state machine can be used to describe which aspect of a component?

In UML 2.5, a ProtocolStateMachine specifies the valid sequences of operation invocations on a classifier (such as a Component or Port) without exposing its internal implementation details. It defines the external protocol or lifecycle contract that callers must adhere to when interacting with the component's interfaces. By declaring states, transitions, and preconditions/postconditions tied to trigger operations, the protocol state machine serves as an explicit behavioral contract. It ensures that consumers invoke operations in a valid order, thereby expressing the external contract of a component rather than its internal realization or structural deployment configuration. This enables precise contract-based modeling across component boundaries.

A. Internals of a component are realized using behavior state machines, activity diagrams, or internal structures, not protocol state machines.

B. Signal flow among connectors is modeled using interaction diagrams or internal structure diagrams rather than protocol state machines.

D. Configuration of an assembly describes structural composition and deployment relationships, which are represented by component or deployment diagrams.

- Object Management Group (OMG)

"OMG Unified Modeling Language (OMG UML)

Version 2.5.1

" formal/2017-12-05

Section 14.4 (Protocol State Machines)

pp. 341–345.

- Object Management Group (OMG)

"OMG Unified Modeling Language (OMG UML)

Version 2.5.1

" formal/2017-12-05

Section 11.5 (Components)

pp. 207–215.