Tutorial for Designer/2000
Lesson 2, page 3
Having completed our level 0 diagram embedded within the context diagram, we will now attempt to create a level 1 diagram. Specifically, we will decompose one of the four processes (say, SRS2 - Maintain Course Records). Let us assume that maintaining course records involves: 1) Validating the course information sent by the departments by comparing this information with a valid course list; and 2) updating the list of courses to be offered with information pertinent to this particular course.
To create a level 1 diagram you will first use the level 0 diagram that we just created.
- First, select the process on which we will construct a level 1 diagram by clicking on it. In this case it will be SR2, Maintain Course Records.
- Then go to FileOpen Down. (See Figure 2.16).
Figure 2.16: Selecting Open Down to draw a level 1 diagram
- Once you select Open Down, immediately you will see the level 1 diagram with the externals, datastores and dataflows linked to the process as it was in our Level 1 diagram. (See Figure 2.17) Initially, you might have to scroll down a little in order to see the externals, because they are attached at the end. Use your mouse to drag and position your datastores and dataflows more towards the center of the page so that they are visible .
Figure 2.17: A first look at the level 1 diagram
- We will now draw our first process, Validate Course Data (SR2.1) within Maintain Course Records. To do this, select the following icon from the toolbar:
- Now click inside the area of Maintain Course Records. Immediately, the window for Create Function will pop up. Type in SRS2.1 and Validate Course Data in Label and Short Definition respectively, and click OK. (See Figure 2.18).
Figure 2.18: The Create Function window
- Using steps 4 and 5 create another process with Label SRS2.2 and Short Definition as Update Course Being Offered Records. Your diagram after creating the two processes should look like Figure 2.19.
Figure 2.19: The level 1 diagram with the two process flows
- We will now create a local datastore within the Maintain Course Records process. To do this, select the following icon from the toolbar and click inside Maintain Course Records.
- Immediately, the Create Datastore window will appear. Type in DS4 as identifier and Approved Courses Database as Name and click OK. (See Figure 2.20).
Figure 2.20: Create Datastore Window
- We will now create a dataflow from SRS2.1 (Validate Course Data) to SRS2.2 (Update Course Being Offered Records). To do this, select the following icon from the toolbar and drag it from SRS2.1 to SRS2.2.
- Immediately, the window for the Create Dataflow will appear. Type in Validated Course as the name and click OK. (See Figure 2.21).
Figure 2.21: The Create Dataflow window
- Using steps 9 and 10 create one more dataflow, namely, 'Course Info. for matching' from DS4 to SRS2.1. Once you create this dataflow, your level 1 diagram will be completed. (See Figure 2.22 for your updated level 1 diagram).
- Your updated model should look like Figure 2.22.
Figure 2.22: The updated level 1 diagram
- Now you will have to connect three dataflows to the processes in the level 1 diagram to complete your diagram. Connect course_info from the external Depts to the process SRS2.1 (Validate Course Data), notification_of_invalid_course from SRS2.1 (Validate Course Data) to the external Depts, and course_insert_update from the process SRS2.2 (Update Course Being Offered Records) to the datastore CRSE. (See Figure 2.23).
Figure 2.23: The completed Level 1 diagram
- You can now save your completed Level 1 diagram by File Save Diagram As SRSDFDLEV1.
In this lesson you have learned how to create level 0 and level 1 dataflow diagrams. Specifically, you have created:
You can use similar methods to create a level 2 diagram if you want to further decompose your processes.
- Frame Functions, Local Functions and Global Functions
- Data Flows
Next, we will learn how to create a process model. For this proceed to lesson 3.
Page 1, Page 2, Page 3 / Back to the tutorial index.
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