UML tool: State diagrams

Examples of UML state diagrams with Modelio

State diagrams are a powerful mechanism for formalizing dynamics that can express several aspects of a class.

UML distinguishes protocol state machines from behavioral state machine.

“Protocol” state machines have very simple semantics and can be used for most classes representing a business notion that always has several different states in its life, with these states changing due to business processes and/or the invocation of operations on the representing class.

Modelio supports the latest UML2 evolutions for state machines, such as entry points, exit points and regions.


Behavioral state machines are used for active objects, in other words, objects that respond to external events. They can express parallelism and provide strong abstraction capacity for the behaviors associated with states.

UML State Diagram - example of phone call