![]() Event trigger – a stimulus that can trigger a source state to fire on satisfying guard condition,.Source state – The state affected by the transition.Until transition fires, the object is in the source state after it fires, it is said to be in the target state. Transition fires means change of state occurs.A transition is a relationship between two states indicating that an object in the first state will perform certain actions and enter the second state when a specified event occurs and specified conditions are satisfied.For example, a Heater in a home might be in any of four states: Idle, Cooling, Heating, Initiating and Active. Deferrable Trigger – A list of events that are not handled in that state but, rather, are postponed and queued for handling by the object in another stateĪn object remains in a state for a finite amount of time.Exit State – Action performed on leaving state.Do Activity – Action performed on entry to state. ![]() Entry – Action performed on entry to state.A transition is rendered as a solid directed line.Ī state is a condition during the life of an object which it may either satisfy some condition for performing some activities, or waiting for some events to be received. Graphically, a state is rendered as a rectangle with rounded corners. In UML, state machines introduce the two new concepts in additional to traditional start chart notation: A state machines are used to model the behavior of objects, use cases, or even entire systems, especially reactive systems, which must respond to signals from actors outside the system. A state machine are used to specify the behavior of objects that must respond to asynchronous stimulus or whose current behavior depends on their past. In other words, when a state machine created where the object it is attached to, that object becomes the owner of the state machine, for example, the object to be attached by the state machine could be a class, use case or even the entire system.Ī state machine diagram is a behavior that specifies the sequences of states an object goes through during its lifetime in response to events. A state machine diagram is used to model the dynamic behavior of individual class objects, use cases, and entire systems.
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