1. Day 4 – Process Modeling: Leveling DFDs Today’s Tools  More on DFDs  Leveling DFDs  Exercise 5 – in class  Introduce TA’s

2. Day 4 – Process Modeling: Leveling DFDs Today’s Tools  More on Process Models  Leveling DFDs  Exercise 5 – in class  Introduce TAs

3. DFD diagrams  Context Diagram  A simplified data flow diagram (DFD) of the scope of an organizational system that shows the system boundaries, external entities that interact with the system and the major information flows between the entities and the system  Fig-0 Diagram  A data flow diagram (DFD) that represents a system’s major processes, data flows and data stores at a high level of detail. It is decomposable.

4. This high level DFD shows the system and its environment. Orders Supplies Order Requisitions Order Confirmation Order Cancellations Shipment Date Changes Beer Donation letters Thank You Letters Summary of Removals Critical Levels Report Order Log Report Inventory Log Report Inventory Discrepancy Report Celis Brewery ITS/IPS Suppliers Management Distributors Recipients Of Free Beer One unnumbered process bubble (name of system) Environmental elements in squares Arrows show data flow to and from the environmental elements. Celis Brewery Example of a Context Diagram

5. Data Flow Diagramming Rules 1.Inputs to a process are always different than outputs 2.Processes must have both an input and an output 3.Objects always have a unique name In order to keep the diagram uncluttered, you can repeat external entities & data stores on a diagram 4.No more than seven processes on one diagram 5.A process has a verb phrase label 6.Data only flows in one direction at a time 7.Data flows are nouns 8.Data must be transformed by a process (cannot be moved directly from one store to another or from an external entity to a data store). 9.Data store has a noun phrase label

6. The Data Flow Diagram—Figure 0 Standard rules apply however,  It is OK to have no actors on Figure 0, if appropriate Remember: No more than seven (7) processes on one diagram  Use multiple levels to describe what is going on

7. Overview of a Leveled DFD Context Diagram Fig 0 Diagram Fig 4 Diagram Fig 4.5 Diagram Drill down to show more detailed processes, data flows, and data stores. Level 1 Level 2

8. ASTA DFDs How many external elements interface with the Proposed Skill Set System? How many data flows are going to and from the system?

9. Compare the two levels

10. Compare Figure 0 and Figure 3 # 3.1 # 3.2 Level 1 dfd

11. Celis Example -- Figure 0 DFD

12. Celis Figure 3 DFD Note that process & data store numbers read left to right and top to bottom. Reminder: This is a Level 1 DFD.

13. Celis Figure 3 DFD

14. Celis fig 3.2 DFD -- drill down detail Notice that DFDs read from left to right, and top to bottom, like a written page.

15. Celis fig 3.2 DFD -- drill down detail The Data Store #’s should match the higher level DFDs. This is a Level 2 DFD. S10 S11 S6

16. DFD Summary  The data flow diagram (DFD) models the processes of an information system  DFDs consist of processes, external entities, data stores, and data flows  DFD modeling begins with the Context Diagram, which depicts the entire system in a single process symbol surrounded by external entities

17. DFD Summary  The first-level DFD (Figure 0) shows the major functional components of the system as processes, connected by data flows to external entities, data stores, and other processes  As needed, successively more detailed levels are developed to promote complete understanding of the system  As you drill down, figures are named by the Process, not the level.

18. Reality & DFD creation  DFDs are usually created from messy notes.  What you think initially might be the best organization of the process usually isn’t what will be the final version.  So, assume you will start with a messy first draft and then clean up the process by leveling the DFDs:  Figuring out what the major processes are for the Figure 0 DFD and then creating the lower level DFDs with the details  TIP: DFD Summary and Rules on Resources pageDFD Summary and Rules

19. Caution about Group Project DFDs Unlike the Client Project, you read text to create your DFDs. Instead of leaving the leveling process (the drill down process) wide open, the text was written with a sense of what the main processes are. The assignment is very specific. Best approach? 1.Maybe create a messy detail DFD, then look back at the process bubbles listed in the requirements. 2.Or maybe start with the process bubbles in the requirements and figure out what needs to be added. 3.No one “right” way…

20. Reminders & Tips  Send email to both professors for faster response  For Next class – bring your laptop  Group Project #1 due Mon., Feb. 9 th, 2pm to one of our offices (CBA 3.414 or 3.416) or to the IROM Dept. office, CBA 5.202  Friday this week -- select and register your team for the Client Project  One person is admin  Team name doesn’t change  Teams of 4 (if you want a team of 5 get that approved)

21. Group Project #1  Do not bind your report  Put team number in footer w/page number  Peer evaluations are due on Mon 9 th by 3pm  Don’t give all 10’s. You have a chance to explain, so if you feel this was the Best Group In The World, you can tell us.  It does not improve your grade  It makes you look bad  CONFIDENTIAL  No one will ever see it except your professors  We look at your peer evals throughout all groups