It is possible
to merge several incoming transitions, or to put several outgoing transitions into
a junction. A junction has no additional semantics. Its notation is a black circle
( Figure 3.65 ). In contrast to an initial state, which always has the same notation,
a junction has always at least one incoming transition. The merging of transitions
is comparable to the merge node in activity diagrams, except that the symbol is
different.
A choice has several outgoing transitions that each have a condition. In contrast
to junctions, the conditions of a choice can be evaluated on the basis of values
that are determined only at the time of the state transition ( Figure 3.65 ). It is
therefore also referred to as a dynamic choice . A choice is not used for merging
of transitions. The notation for choices is identical to the one for a decision in an
activity diagram??”a rhombus.
3.7 The State Machine Diagram
FIGURE 3-65
A state machine with choice and junction.
202 CHAPTER 3 UML??”Unifi ed Modeling Language
A terminate state causes the state machine to exit without the context object
taking on a new value confi guration.
Pages:
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391