1 files changed, 219 insertions, 0 deletions
diff --git a/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/20 - Class Diagram: Association & Aggregation Relationships - lang_en_vs5.srt b/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/20 - Class Diagram: Association & Aggregation Relationships - lang_en_vs5.srt
new file mode 100644
index 0000000..8770928
--- /dev/null
+++ b/usth/ICT2.7/P2L2 OO Software Engineering and UML Subtitles/20 - Class Diagram: Association & Aggregation Relationships - lang_en_vs5.srt
@@ -0,0 +1,219 @@
+1
+00:00:00,080 --> 00:00:02,469
+The next example of relationship we're going to look at is
+
+2
+00:00:02,469 --> 00:00:06,740
+the association relationship. This is a relationship in which objects of
+
+3
+00:00:06,740 --> 00:00:09,570
+one class are connected to objects of another. And it's
+
+4
+00:00:09,570 --> 00:00:12,480
+called an has a relationship. So it means that objects of
+
+5
+00:00:12,480 --> 00:00:15,930
+one class have objects of another class. So let's see
+
+6
+00:00:15,930 --> 00:00:18,750
+what that means. Let's do it by considering two classes in
+
+7
+00:00:18,750 --> 00:00:22,370
+our example system. The student class and the course offering class.
+
+8
+00:00:22,370 --> 00:00:25,300
+In this case, there is an association between the student and
+
+9
+00:00:25,300 --> 00:00:28,010
+the course offering, because the student is registering for the
+
+10
+00:00:28,010 --> 00:00:31,750
+course offering. So, in a sense, the course offering has students.
+
+11
+00:00:31,750 --> 00:00:35,360
+Contains students, to indicate this fact we add a solid
+
+12
+00:00:35,360 --> 00:00:38,750
+line between the student class and the course offering. And the
+
+13
+00:00:38,750 --> 00:00:40,540
+fact that having a solid line doesn't really tell us
+
+14
+00:00:40,540 --> 00:00:44,780
+much about the nature of the relationship, so to clarify such
+
+15
+00:00:44,780 --> 00:00:47,550
+nature we can use what we call adornments that we
+
+16
+00:00:47,550 --> 00:00:51,010
+can apply to associations we can add to associations to clarify
+
+17
+00:00:51,010 --> 00:00:53,850
+their meaning. In particular we can add a label to
+
+18
+00:00:53,850 --> 00:00:57,550
+an association and the label describes the nature of the relationship.
+
+19
+00:00:57,550 --> 00:01:00,440
+In this case, for example, it clarifies that the student
+
+20
+00:01:00,440 --> 00:01:03,970
+registers for CourseOffering. We can also add a triangle to
+
+21
+00:01:03,970 --> 00:01:07,050
+further clarify the direction of the relationship. So in this
+
+22
+00:01:07,050 --> 00:01:10,240
+case, the triangle will indicate that it's the student That registers
+
+23
+00:01:10,240 --> 00:01:13,120
+for the course offering, and not the other way around. Another
+
+24
+00:01:13,120 --> 00:01:16,650
+important adornment or limitation that we can put on an association,
+
+25
+00:01:16,650 --> 00:01:20,800
+is multiplicity. Multiplicity defines the number of instances of one
+
+26
+00:01:20,800 --> 00:01:23,540
+class that are related to one instance of the other
+
+27
+00:01:23,540 --> 00:01:26,900
+class. We can define multiplicity at either end of the
+
+28
+00:01:26,900 --> 00:01:29,620
+relationship. In this case, for instance, we can say that
+
+29
+00:01:29,620 --> 00:01:31,890
+if we look at the student, the student can register
+
+30
+00:01:31,890 --> 00:01:35,410
+for two or more course offerings. Whereas, if we look
+
+31
+00:01:35,410 --> 00:01:37,560
+at the course offering, we can say that each course
+
+32
+00:01:37,560 --> 00:01:42,260
+offering can have or can enroll between 1 and 50 students.
+
+33
+00:01:42,260 --> 00:01:45,120
+So as you can see by adding a label, a direction,
+
+34
+00:01:45,120 --> 00:01:49,590
+and multiplicity, we make it much clearer what the relationship is
+
+35
+00:01:49,590 --> 00:01:52,170
+and what it means and what are its characteristics. As we
+
+36
+00:01:52,170 --> 00:01:55,130
+saw when we introduced relationships, there is a different kind of
+
+37
+00:01:55,130 --> 00:01:58,860
+association, kind of a specialized one, which we call aggregation. So
+
+38
+00:01:58,860 --> 00:02:01,130
+here we're going to look at an example of an aggregation. So
+
+39
+00:02:01,130 --> 00:02:03,490
+first of all what is an aggregation? An aggregation is a
+
+40
+00:02:03,490 --> 00:02:07,580
+relationship between 2 classes in which 1 represents a larger class
+
+41
+00:02:07,580 --> 00:02:10,610
+like a whole which consists of smaller classes which are
+
+42
+00:02:10,610 --> 00:02:13,430
+the parts of this whole. So lets look at an example
+
+43
+00:02:13,430 --> 00:02:16,960
+in the context of our system. Let's consider a Course
+
+44
+00:02:16,960 --> 00:02:19,160
+and the CourseOffering. And in this case, we can see
+
+45
+00:02:19,160 --> 00:02:23,000
+that the Course consists of multiple CourseOfferings. So in
+
+46
+00:02:23,000 --> 00:02:26,520
+a sense, a course is a whole and the course offerings
+
+47
+00:02:26,520 --> 00:02:29,430
+are the parts of this whole. So this a perfect case
+
+48
+00:02:29,430 --> 00:02:32,620
+in which we will use an aggregation to express this relationship.
+
+49
+00:02:32,620 --> 00:02:37,630
+So we will add a solid line with a diamond on the side of the whole class
+
+50
+00:02:37,630 --> 00:02:42,380
+to indicate that the course consists of multiple course offerings.
+
+51
+00:02:42,380 --> 00:02:44,670
+And as we did for associations even though we
+
+52
+00:02:44,670 --> 00:02:46,010
+are not going to do it for this specific
+
+53
+00:02:46,010 --> 00:02:49,540
+example, we could also in this case add multiplicity
+
+54
+00:02:49,540 --> 00:02:52,830
+information on the aggregation to indicate how many classes
+
+55
+00:02:52,830 --> 00:02:55,310
+of the two types are involved in the relationships.