Formal methods | Automata (computation) | Models of computation
UML state machine
UML state machine, also known as UML statechart, is an extension of the mathematical concept of a finite automaton in computer science applications as expressed in the Unified Modeling Language (UML) notation. The concepts behind it are about organizing the way a device, computer program, or other (often technical) process works such that an entity or each of its sub-entities is always in exactly one of a number of possible states and where there are well-defined conditional transitions between these states. UML state machine is an object-based variant of Harel statechart, adapted and extended by UML. The goal of UML state machines is to overcome the main limitations of traditional finite-state machines while retaining their main benefits. UML statecharts introduce the new concepts of and , while extending the notion of . UML state machines have the characteristics of both Mealy machines and Moore machines. They support that depend on both the state of the system and the triggering , as in Mealy machines, as well as , which are associated with states rather than transitions, as in Moore machines. The term "UML state machine" can refer to two kinds of state machines: behavioral state machines and protocol state machines. Behavioral state machines can be used to model the behavior of individual entities (e.g., class instances), a subsystem, a package, or even an entire system. Protocol state machines are used to express usage protocols and can be used to specify the legal usage scenarios of classifiers, interfaces, and ports. (Wikipedia).
