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diff --git a/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/31 - UML Behavioral Diagrams: Sequence - lang_en_vs5.srt b/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/31 - UML Behavioral Diagrams: Sequence - lang_en_vs5.srt deleted file mode 100644 index cbeb4d8..0000000 --- a/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/31 - UML Behavioral Diagrams: Sequence - lang_en_vs5.srt +++ /dev/null @@ -1,227 +0,0 @@ -1 -00:00:00,080 --> 00:00:02,400 -Now that we have seen use cases, the next behavioral - -2 -00:00:02,400 --> 00:00:05,540 -diagram I want to discuss is the sequence diagram. So - -3 -00:00:05,540 --> 00:00:08,070 -what is a sequence diagram? It is an interaction diagram - -4 -00:00:08,070 --> 00:00:12,710 -that emphasizes how objects communicate and the time ordering of - -5 -00:00:12,710 --> 00:00:15,940 -the messages between objects. To illustrate sequence diagrams in a - -6 -00:00:15,940 --> 00:00:18,600 -practical way, and hopefully in a clear way, I will - -7 -00:00:18,600 --> 00:00:21,960 -introduce them by creating an actual sequence diagram using an - -8 -00:00:21,960 --> 00:00:25,160 -example taken from our course management system. So let's see what - -9 -00:00:25,160 --> 00:00:28,050 -are the steps needed to build such a sequence diagram. The first - -10 -00:00:28,050 --> 00:00:30,900 -thing we want to do is place the objects that participate in - -11 -00:00:30,900 --> 00:00:34,460 -the interaction at the top of the diagram along the x-axis, and - -12 -00:00:34,460 --> 00:00:36,410 -you also want to place them in a specific way. You want - -13 -00:00:36,410 --> 00:00:39,770 -to place objects that initiate the interaction at the left, and place - -14 -00:00:39,770 --> 00:00:42,260 -increasingly more subordinate objects to the - -15 -00:00:42,260 --> 00:00:44,430 -right. So basically, this should reflect - -16 -00:00:44,430 --> 00:00:47,660 -the way the events will flow for the majority of the interactions - -17 -00:00:47,660 --> 00:00:50,202 -in the system. Next thing you want to do is to add - -18 -00:00:50,202 --> 00:00:53,910 -what is called the object lifeline. It's a vertical line that - -19 -00:00:53,910 --> 00:00:57,300 -shows the existence of objects over a period of time. And - -20 -00:00:57,300 --> 00:01:00,660 -it's normally represented with a dashed line, except for the outermost - -21 -00:01:00,660 --> 00:01:03,190 -object for which it is a solid line. Now that you - -22 -00:01:03,190 --> 00:01:06,450 -have your object lifeline you can start placing messages that these - -23 -00:01:06,450 --> 00:01:09,285 -objects send and receive. You want to put them along the - -24 -00:01:09,285 --> 00:01:12,860 -y-axis in order of increasing time, from top to bottom. And - -25 -00:01:12,860 --> 00:01:15,550 -you can also put a number on the message to further - -26 -00:01:15,550 --> 00:01:18,230 -clarify the sequence. So in this case what we're showing - -27 -00:01:18,230 --> 00:01:21,550 -is that the student will send the fill in info - -28 -00:01:21,550 --> 00:01:24,330 -message to the registration form. And this is the first - -29 -00:01:24,330 --> 00:01:27,960 -message in the sequence diagram, the first interaction. Then the student - -30 -00:01:27,960 --> 00:01:30,900 -might submit the form and this is also a message - -31 -00:01:30,900 --> 00:01:33,370 -that goes to the registration form. At this point, when - -32 -00:01:33,370 --> 00:01:36,440 -the submission takes place, the registration form will send the - -33 -00:01:36,440 --> 00:01:39,990 -message, so it will invoke some functionality in the registration manager. - -34 -00:01:39,990 --> 00:01:43,560 -Specifically you will invoke the add course functionality - -35 -00:01:43,560 --> 00:01:46,400 -and pass Joe, the name of the student and - -36 -00:01:46,400 --> 00:01:49,410 -Math 101 which is the specific course for which - -37 -00:01:49,410 --> 00:01:53,180 -Joe is registering. Then the registration manager will ask - -38 -00:01:53,180 --> 00:01:56,780 -the Math 101 course whether it accepts registrations, - -39 -00:01:56,780 --> 00:01:59,780 -and the interaction will continue. So that Math 101 - -40 -00:01:59,780 --> 00:02:02,820 -will actually check for a specific offering, if everything - -41 -00:02:02,820 --> 00:02:05,070 -goes fine, you will receive an ack, you'll send - -42 -00:02:05,070 --> 00:02:07,180 -back the act to the registration manager and so - -43 -00:02:07,180 --> 00:02:10,650 -on. Until at the end, Joe will be registered for - -44 -00:02:10,650 --> 00:02:13,390 -Math 101. As you can see, it is very - -45 -00:02:13,390 --> 00:02:17,600 -easy to see how the interaction occurs between these different - -46 -00:02:17,600 --> 00:02:21,010 -objects at run time, dynamically. So what the behavior - -47 -00:02:21,010 --> 00:02:24,070 -of the system is for this specific scenario. So the - -48 -00:02:24,070 --> 00:02:26,780 -last notational element that I want to add to this - -49 -00:02:26,780 --> 00:02:30,350 -diagram is the focus of control. Which is this tall - -50 -00:02:30,350 --> 00:02:32,880 -thin rectangle, that shows the period of time - -51 -00:02:32,880 --> 00:02:35,190 -that an object is performing an action, either - -52 -00:02:35,190 --> 00:02:37,270 -directly or indirectly. So if we look at - -53 -00:02:37,270 --> 00:02:39,240 -the registration form, this is telling us that - -54 -00:02:39,240 --> 00:02:41,670 -the registration form is active for this amount - -55 -00:02:41,670 --> 00:02:43,170 -of time. And the same thing we can - -56 -00:02:43,170 --> 00:02:45,520 -do for the registration manager, the Math 101 - -57 -00:02:45,520 --> 00:02:49,170 -course offering, and the Math 101 specific section. |