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CHAPTER 32

Systems Modeling
and Design

IN THIS CHAPER

• Entity Relationship Diagrammer778
• Functional Hierarchy Diagrammer784
• Dataflow Diagrammer790
• Systems Design795
• Database Design Wizard795
• The Data Diagrammer799
• The Application Design Wizard804
• The Module Structure Diagrammer805

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The system modeling tools are used to do a large portion of the analysis work in the life cycle of an Oracle project. The tools discussed in this section ”the Process Modeller, the Entity Relationship Diagrammer, the Functional Hierarchy Diagrammer, the Dataflow Diagrammer, and the Module Data Diagrammer ”all have a very similar screen format. We'll take a look at these tools and some of the specific ways you can create screens to help you model and design your system.

The Process Modeller is the the first tool in the Designer/2000 application development cycle. You have already seen in Chapter 30, "Introduction to and Installation of Designer/2000," how the Process Modeller can help you map and analyze business processes.

The Entity Relationship Diagrammer provides the user with a visual representation of entities ”logical groupings of information and their relationships to one another. Each entity can then be further classified by individual attributes, objects that identify the entity, unique identifiers, and domains.

The Function Hierarchy Diagrammer allows you to make use of the entities previously defined in the entity relationship diagrammer by their usage in the creation of business functions. Functions will eventually become the screens, reports , menus , and PL/SQL of the system.

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Functions include a screen for the maintenance of all the base tables in the system, as well as functions for each of the areas identified to be created as components of the system. Functions can be triggered (called) by other functions.

The Dataflow Diagrammer gives a visual representation of how a system is integrated into the outside world. It provides information about when the data is brought in, its format, and where it will eventually reside. If you build a system that populates base tables through interfaces to external systems or sends information to external systems, the Dataflow Diagrammer allows you to capture this activity.

On the top of each diagrammer tool is a pull-down menu as well as a toolbar of icons. All the functions these icons perform can also be found on the menubars under Edit, View, Utilities, and Tools. Whether the user wants to use the icons or the menu is a matter of style. For the most part, the descriptions in this chapter use the icons rather than the menubar.

Creating, Opening, and Saving a Diagram

Initially, you may create a new diagram either by choosing New from the File menu or by
selecting the New icon. The New icon looks like a document with the top-right corner folded downward. If the diagram is already in existence, choose Open from the File menu or the

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select Folder icon. When saving the diagram, choose File and then Save/Save As or select the Diskette icon. When you choose any of these icons from the Designer/2000 toolset, help is available. The help message appears in a balloon to the right of the icon when you move your cursor next to the icon (and do not click the mouse). You can also get help by selecting anything on your diagram (an icon or an element) and selecting the Question Mark icon. Finally, you can search for help on any topic from the help menu selection.

Sizing the Diagram

In addition to the previously mentioned functions, there are several others used in sizing the diagram. You may enlarge the diagram by clicking the icon of the magnifying glass containing the plus sign; consequently, to shrink the diagram click the magnifying glass containing the minus sign. After you have enlarged or shrunk the diagram and want it to resume to its normal size , click the icon of the magnifying glass in the top-left corner. The icon of the magnifying glass containing several rectangles allows the user to view the entire diagram on one screen. The larger the diagram grows, the smaller the objects will appear when using this icon. Finally, there is an icon for autolayout that allows the tool to determine the best positioning of the objects on the canvas. The user may click the autolayout more than once to continue the autolayout process until the diagram most closely resembles what the user had in mind. There is also a revert layout that allows the user to go back one level.

NOTE

Because the Systems Modeling tool uses logical objects, it is sometimes necessary to use somewhat unconventional modeling methods in order to effectively communicate the system requirements to the users.

Summary Information

Initially, when your diagram is started, you might want to fill in the summary information so that you can easily identify the diagram when it is printed. Under the File menu is a choice called Summary Information. A window pops up showing you all the choices for information to be included on your chart.

Starting Up

In a Windows operating systems environment, select Designer/2000. You will first be prompted to connect by entering your user ID, password, and connect string to the application. Once connected, you will be viewing a canvas distributed into several primary areas. Let's look first at the Entity Relationship Diagrammer.

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Entity Relationship Diagrammer

This section provides a brief overview about how to model information using the Entity Relationship Diagrammer. The entities are logical units that can eventually become the tables, views, and snapshots in your system. The Summary Information tabbed dialog box enables you to designate label information and shows modifaction dates and text settings.

Select any information you want to display on the diagram. If you want to include your name or a diagram title, you need to fill in these items in the Summary Information dialog.

Adding the Entities

You are now ready to start adding information or entities to your diagram. You might have already created your entities in RON ”the Repository Object Navigator, which you learned about and saw in Figure 31.5 in the preceding chapter ”or some might have been entered by another user in RON or on another diagram. You can also create them in the Entity Relationship Diagrammer. If you need to create entities, select the Entity icon. After you select the icon, drag your cursor onto the diagram page. After you select a spot for the entity, you will be prompted for a name, short name, and plural for your entity. The short name and plural will eventually become the table alias and table name.

After the entity is created, you can edit the entity by double-clicking anywhere within the confines of its shape. You can add attributes, unique keys, synonyms, and any descriptive text at this point. You may show all the attributes if the size of your entity is sufficient. There are other less space-consuming options. If you choose to show all attributes and the space is too limited, a set of dots signifies that more information is available about the entity. You may increase or decrease the size of the entity by selecting it and dragging it from one of its boldfaced points. After you create an entity on your diagram, the entity and any information you add or edit on it is automatically added/updated in the RON.

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If you want to create more than one entity without having to select the button each time, hold down the Shift key when you select the entity button. When you are ready to move to another activity, press another button on the icon bar.

You can also select entities from RON. From the Menu bar choose Edit Include Entities. A list of available entities will appear. After you select the entities you want to include on the diagram, the diagrammer automatically puts on the diagram those entities as well as any relationships it already has to any other entities on the diagram. You can bring in an entity with or without its relationships. To bring it in with relationships, select the With Relationships box before pressing the OK button. There are several options available when adding entities to an existing diagram that enable the user to control where the new information will appear on the canvas.

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