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PATTERNS OF DATA MODELING- P15: Models provide the means for building quality software in a predictable manner. Models let developers think deeply about software and cope with large size and complexity. Developers can think abstractly before becoming enmeshed in the details of writing code. Although models are beneficial, they can be difficult to construct. That is where patterns come in. Patterns provide building blocks that help developers construct models faster and better. | 3.4 Connection Directed Graph Template 51 Node table Edge table Connection table Connection table cont node ID node Name edge ID edge Name connec tionID node ID edge ID source OrSink connec tionID node ID edge ID source OrSink 1 A 51 c 1 1 51 source 8 5 54 sink 2 B 52 d 2 3 51 sink 9 3 55 source 3 C 53 e 3 1 52 source 10 6 55 sink 4 D 54 f 4 4 52 sink 11 4 56 source 5 E 55 g 5 1 53 source 12 6 56 sink 6 F 56 h 6 5 53 sink 13 5 57 source 57 i 7 2 54 source 14 6 57 sink Figure 3.32 Connection directed graph Populated tables. t Node table Edge table Connection table Connection table cont node ID node Name edge ID edge Name connec tionID node ID edge ID source OrSink connec tionID node ID edge ID source OrSink 11 X 61 r 21 11 61 source 24 12 62 sink 12 Y 62 s 22 12 61 sink 25 11 63 source 63 t 23 11 62 source 26 11 63 sink Figure 3.33 Connection directed graph Populated tables. 52 Chapter 3 Directed Graph Template 3.4.5 Example The connection template is sometimes helpful for representing directed graphs as Figure 3.34 illustrates. A manufacturing plant can have a variety of equipment that is connected by piping. Nozzles connect piping to equipment and have a direction of normal fluid flow. Figure 3.34 Connection directed graph Equipment and piping model. 3.5 Simple DG Changing over Time Template There are two templates for directed graphs that can change over time. The first this section is based on the simple directed graph. The second next section is based on the node and edge directed graph. It is also possible to extend the connection template for variations over time but I have never seen it used in practice. 3.5.1 UML Template The template for simple directed graphs that change over time Figure 3.35 is similar to the tree template in Section 2.5. Figure 3.35 separates an entity from its directed graph position node because the timeline for an entity can differ from that of its involvement in a graph. Figure 3.35 Simple directed graph changing over time UML .
