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diff --git a/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/32 - UML Behavioral Diagrams: State Transition Diagram - lang_en_vs5.srt b/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/32 - UML Behavioral Diagrams: State Transition Diagram - lang_en_vs5.srt deleted file mode 100644 index ab1bd6a..0000000 --- a/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/32 - UML Behavioral Diagrams: State Transition Diagram - lang_en_vs5.srt +++ /dev/null @@ -1,175 +0,0 @@ -1 -00:00:00,100 --> 00:00:02,430 -The very last diagram that I want to discuss is - -2 -00:00:02,430 --> 00:00:05,900 -the state transition diagram. The state transition diagram is defined for - -3 -00:00:05,900 --> 00:00:09,270 -each relevant class in the system and basically shows the - -4 -00:00:09,270 --> 00:00:12,880 -possible live history of a given class or object. So what - -5 -00:00:12,880 --> 00:00:15,090 -does it mean to describe the life history? It means - -6 -00:00:15,090 --> 00:00:18,630 -that it describes the possible states of the class as defined - -7 -00:00:18,630 --> 00:00:21,910 -by the values of the class attributes. And it also describes - -8 -00:00:21,910 --> 00:00:25,710 -the events that cause a transition from one state to another. - -9 -00:00:25,710 --> 00:00:28,800 -Finally, it describes the actions that result from a state - -10 -00:00:28,800 --> 00:00:31,050 -change. So if you put all of this together you - -11 -00:00:31,050 --> 00:00:33,760 -can see how this can represent the whole history of - -12 -00:00:33,760 --> 00:00:36,860 -the class, from its creation to its destruction. So let me - -13 -00:00:36,860 --> 00:00:40,610 -discuss the transition diagram in more detail, and also provide - -14 -00:00:40,610 --> 00:00:43,550 -information about the notation used to represent them. We have - -15 -00:00:43,550 --> 00:00:46,770 -states, that are represented by ovals with a name. And - -16 -00:00:46,770 --> 00:00:51,820 -we have transitions marked by the event that triggers the transition. - -17 -00:00:51,820 --> 00:00:55,500 -What transitions indicate is the passage from one state to - -18 -00:00:55,500 --> 00:00:59,430 -another state as the consequence of some external stimuli. Notice - -19 -00:00:59,430 --> 00:01:01,930 -that not all events will cause a state transition. So - -20 -00:01:01,930 --> 00:01:04,930 -for example, some events might be consumed within a single state. - -21 -00:01:04,930 --> 00:01:06,500 -And we'll get to that in a second. But in - -22 -00:01:06,500 --> 00:01:10,200 -most cases, an event will trigger some state transition. Events - -23 -00:01:10,200 --> 00:01:13,480 -may also produce actions and they may also have attributes - -24 -00:01:13,480 --> 00:01:17,100 -which are analogous to parameters in a method call. And Boolean - -25 -00:01:17,100 --> 00:01:20,830 -conditions that guard the state transition that is prevented - -26 -00:01:20,830 --> 00:01:22,860 -from happening in the case the conditions are not - -27 -00:01:22,860 --> 00:01:26,630 -satisfied. States may also be associated with activities and - -28 -00:01:26,630 --> 00:01:31,450 -actions. Specifically, activities are operations performed by an object - -29 -00:01:31,450 --> 00:01:33,410 -when it is in a given state and that - -30 -00:01:33,410 --> 00:01:36,690 -takes time to complete. Actions, conversely, just like the - -31 -00:01:36,690 --> 00:01:40,270 -actions corresponding to an event are instantaneous operations that - -32 -00:01:40,270 --> 00:01:42,420 -are performed by an object. And can be triggered - -33 -00:01:42,420 --> 00:01:46,050 -on entry. So, when the object reaches a given state, - -34 -00:01:46,050 --> 00:01:48,970 -when the object exits that state, and also when a - -35 -00:01:48,970 --> 00:01:53,240 -specific event occurs. And in this case, this notation is - -36 -00:01:53,240 --> 00:01:55,930 -basically a shortcut for any event that will cause a - -37 -00:01:55,930 --> 00:01:58,840 -state transition that will bring the object back into the - -38 -00:01:58,840 --> 00:02:01,696 -same state. Since we have several actions and activities, it - -39 -00:02:01,696 --> 00:02:04,480 -is probably worthwhile clarifyinig the ordering of such actions and - -40 -00:02:04,480 --> 00:02:07,559 -activities. So the way in which these actions and activities - -41 -00:02:07,559 --> 00:02:10,079 -occur is, first of all, we have the actions on the - -42 -00:02:10,079 --> 00:02:13,737 -incoming transition, so this is performed first. Then if there is an - -43 -00:02:13,737 --> 00:02:17,321 -entry action that is the next action that would be performed, then - -44 -00:02:17,321 --> 00:02:22,370 -we have activity and event actions as appropriate. And finally exit actions. |