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   <title>State machine glossary</title><link rel="stylesheet" href="boostbook.css" type="text/css"><meta name="generator" content="DocBook XSL-NS Stylesheets V1.75.2"><link rel="home" href="index.html" title="Meta State Machine (MSM) V2.12"><link rel="up" href="ch02.html" title="Chapter&nbsp;2.&nbsp;UML Short Guide"><link rel="prev" href="ch02s02.html" title="Concepts"><link rel="next" href="ch03.html" title="Chapter&nbsp;3.&nbsp;Tutorial"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">State machine glossary</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch02s02.html">Prev</a>&nbsp;</td><th width="60%" align="center">Chapter&nbsp;2.&nbsp;UML Short Guide</th><td width="20%" align="right">&nbsp;<a accesskey="n" href="ch03.html">Next</a></td></tr></table><hr></div><div class="sect1" title="State machine glossary"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="d0e344"></a>State machine glossary</h2></div></div></div><p>
                    </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>state machine: the life cycle of a thing. It is made of states,
                                regions, transitions and processes incoming events.</p></li><li class="listitem"><p>state: a stage in the life cycle of a state machine. A state (like
                                a submachine) can have an entry and exit behaviors.</p></li><li class="listitem"><p>event: an incident provoking (or not) a reaction of the state
                                machine</p></li><li class="listitem"><p>transition: a specification of how a state machine reacts to an
                                event. It specifies a source state, the event triggering the
                                transition, the target state (which will become the newly active
                                state if the transition is triggered), guard and actions.</p></li><li class="listitem"><p>action: an operation executed during the triggering of the
                                transition.</p></li><li class="listitem"><p>guard: a boolean operation being able to prevent the triggering of
                                a transition which would otherwise fire.</p></li><li class="listitem"><p>transition table: representation of a state machine. A state
                                machine diagram is a graphical, but incomplete representation of the
                                same model. A transition table, on the other hand, is a complete
                                representation.</p></li><li class="listitem"><p>initial state: The state in which the state machine starts. Having
                                several orthogonal regions means having as many initial
                                states.</p></li><li class="listitem"><p>submachine: A submachine is a state machine inserted as a state in
                                another state machine and can be found several times in a same state
                                machine.</p></li><li class="listitem"><p>orthogonal regions: (logical) parallel flow of execution of a
                                state machine. Every region of a state machine gets a chance to
                                process an incoming event.</p></li><li class="listitem"><p>terminate pseudo-state: when this state becomes active, it
                                terminates the execution of the whole state machine. MSM does not
                                destroy the state machine as required by the UML standard, however,
                                which lets you keep all the state machine's data.</p></li><li class="listitem"><p>entry/exit pseudo state: defined for submachines and are defined
                                as a connection between a transition outside of the submachine and a
                                transition inside the submachine. It is a way to enter or leave a
                                submachine through a predefined point.</p></li><li class="listitem"><p>fork: a fork allows explicit entry into several orthogonal regions
                                of a submachine.</p></li><li class="listitem"><p>history: a history is a way to remember the active state of a
                                submachine so that the submachine can proceed in its last active
                                state next time it becomes active.</p></li><li class="listitem"><p>completion events (also called completion/anonymous transitions):
                                when a transition has no named event triggering it, it automatically
                                fires when the source state is active, unless a guard forbids
                                it.</p></li><li class="listitem"><p>transition conflict: a conflict is present if for a given source
                                state and incoming event, several transitions are possible. UML
                                specifies that guard conditions have to solve the conflict.</p></li><li class="listitem"><p>internal transitions: transition from a state to itself without
                                having exit and entry actions being called.</p></li></ul></div><p>
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