Studio III.1 Introduction to IBMS/DFD tool

This studio introduces the DFD tool of the IBMS CASE system. The tool helps the users drawing a standard data flow diagram (a process-oriented model of information systems) for systems analysis and mapping it into a SER model (a data-oriented model of information systems) for database design.

Objective:

• Learn how to create a DFD using IBMS/DFD tool.
• Learn how to map a DFD to a SER model using IBMS/DFD tool.

Steps to start the IBMS/DFD modeling tool:

• Double click on the IBMS icon. You will see the welcome screen (with the moving spaceship). Click anywhere inside the welcome screen to bring up the first screen.
• Under "tools", select DFD Modeling. The IBMS will pop up the Data Flow Diagram window. Its menu bar has the File, Edit, Insert, Font, Tool, Window and Help options. Its tool box on the right contains 10 icons, representing (from left to right and top to bottom) pointer, cut, data flow, process, external entity, data store, zoom-out, zoom-in, decompose, and compose operations, respectively.

Working with IBMS/DFD modeling tool:

Scenario:

• Suppose we want to draw the level 1 DFD as shown in Figure 1.1 and the level 2 in Figure 1.2 where the process P1 is decomposed into P11 and P12:

Figure 1.1: The level 1 DFD

Figure 1.2: The level 2 DFD

Steps:

To draw the level 1 DFD in Figure 1.1:

• Left click on the External-Entity icon in the tool box and place it on the work area. The input dialogue box will prompt you to input information of the external entity. Key in E1 as External Entity Name for the external entity you just created.
• Left click on the Process icon in the tool box and place it on the work area. The input dialogue box will prompt you to input information of the process. Key in P1 and 1, respectively, as the Process Name and Process Number.
• Left click on the Data-Store icon in the tool box and place it on the work area. The input dialogue box will prompt you to input information of the data store. Key in D1 as the Name.
• Left click on the Data-Flow icon in the tool box, left click on the external entity E1, and left click on the process P1. The input dialogue box will prompt you to input information of the data flow. Key in F1 as the Name.
• Left click on the Data-Flow icon in the tool box, left click on the external data store D1, and left click on the process P1. The input dialogue box will prompt you to input information of the data flow. Key in F2 as the Name.
• Left click on the Data-Flow icon in the tool box, left click on the process P1, and left click on the data store D1. The input dialogue box will prompt you to input information of the data flow. Key in F3 as the Name.

To move the DFD components:

• Left click on the Pointer icon in the tool box, point to the component, and hold LeftBotton to move to the new location desired in the work area and drop it there (release the LeftBotton).

To edit information of the DFD components:

• Right click on the DFD component. The input dialogue box will prompt you to edit information of that component.

To remove the DFD components:

• Left click on the Cut icon in the tool box, and left click on the DFD component you want to remove. The confirmation box will prompt you to confirm the removal.

To zoom-in and zoom-out the DFD:

• Left click on the Zoom-In (Zoom-Out) icon in the tool box, and left click on the work area. The IBMS/DFD tool will zoom in (zoom out) the DFD.

To draw the level 2 DFD in Figure 1.2:

• Left click on the Decompose icon in the tool box and left click on the process P1. The IBMS/DFD tool will show the diagram in Figure 1.3. A small blue box represents P1. This small blue box can be dragged into a process defined in this level.

Figure 1.3: The small blue box of DFD.

• Left click on the Process icon in the tool box and create the processes P11 and P12 (names). Number them, respectively as 1.1 and 1.2. Next, left click on the Pointer icon in the tool box and then point to the small blue icon, hold LeftBotton to drag it to P11 or P12 as desired.
• Left click on the Data-Flow icon in the tool box, left click on the process P11, and left click on the process P12. The input dialogue box will prompt you to input information of the data flow. Key in F4 as the Name.

To save the DFD:

• Under File menu, choose Save or SaveAs. Input the name and extension of the DFD (the default extension is DFD) and specify folder for the DFD to be saved. Then click OK.

To print the DFD:

• Under File menu, choose Print. Input appropriate information. Then click OK.

To write report:

• Under File menu, choose Write Report. Input appropriate information. Then click OK.

To save the DFD in other graphic formats using Paint program of MS Window:

• Open the DFD and display the desired diagram. Press PrintScreen button to get the screen in memory buffer.
• Click Start, choose Program->Accessories->Paint. Under the Edit menu of Paint program, choose Paste to paste the screen shot from memory buffer into the work area. Modify the picture as desired and then save in an appropriate graphic format.

To input data items:

Suppose there are 5 data items for the system: item1, item2, item3, item4, and item5.

• Under Item menu, choose Item. Click New. The input dialogue box will prompt you to input information. Input item1 as the first Name and click OK. Do the same to input item2, item3, item4, and item5. Click Cancel to finish. Then, click OK to close this data item entering session.

To assign data items to data flows and data stores

Suppose F1 consists of item1 while F2, F3, F4, and D1 each consist of all data items.

• Left click Pointer icon in the tool box, then point to F1 and left click. In the Assign Items dialogue box, click item1 and OK.
• Point to F2 and left click. In the Assign Items dialogue box, click all data items and OK. Do the same for F3, F4, and D1.

To map the DFD to SER model:

• Under File menu, choose Map to SER. Input the name and its extension as SERDFD.ser. Then click OK.

To view the SER model:

• Under "tools" of IBMS, select SER Modeling. Under File menu of Semantic-ER window, choose Open to open SERDFD.ser. You'll get the first level SER model as shown in Figure 1.4(a). Left click Decompose icon, and left click on DFD-APPL subject. You'll get the second level SER model as shown in Figure 1.4(b). You may need to redraw the second level SER model; if so, choose Redraw under Tool menu and click Fully Optimized Result, then click OK.

Figure 1.4(a): The first level SER model.

Figure 1.4(a): The second level SER model.