1. DON’T DO IT! IT’S NOT HOPELESS

2. Documentation

3. Flowcharting Due to thier complexity (when looking at them), flowcharts intimidate many people. However, if you take a very methodical approach to constructing flowcharts, it’s really not bad!

4. Flowcharting methodical approach Step One: For each INTERNAL ENTITY (in your physical DFD), create a heading and flowchart column. MailroomAcct. RecCPTRCashier Note that there is one column created for each of the internal entities in the Causeway narrative

5. Flowcharting methodical approach Step Two: Flowchart each activity - one by one! For each activity (other than a send or receive) draw a computer process symbol rectangle, a manual process symbol trapezoid, or a keyboard for “keyed” in information. computer process symbol computer process symbol manual process symbol manual process symbol 2. Endorse checks. 2. Endorse checks. 13. Verifies the invoice is open and correct amt is pd. 13. Verifies the invoice is open and correct amt is pd. Keyboard symbol Keyboard symbol 7. Enters data into CPTR. 7. Enters data into CPTR.

6. Receiving and sending do not require a process symbol Customer Endorses checks Checks R/As 1 2 Causeway example Causeway example

7. If one entity performs several activities in sequence, you can put them in a single process symbol example from Causeway Endorse checks Annotate R/A Prepare B/T Endorse checks Annotate R/A Prepare B/T Endorse checks Annotate R/A Prepare B/T Endorse checks Annotate R/A Prepare B/T Endorse checks Annotate R/A Prepare B/T Endorse checks Annotate R/A Prepare B/T

8. Just add activities one by one! Unless it is really simple to draw an arrow to or from another entity, USE ON PAGE CONNECTORS! (a small circle) Unless it is really simple to draw an arrow to or from another entity, USE ON PAGE CONNECTORS! (a small circle) A A Customer Endorses checks Annotate R/As Prepare B/T Endorses checks Annotate R/As Prepare B/T 1 2,3,4 Batched Checks B/T B B Checks R/As Batched R/As

9. Flowchart symbols 1Computer process 2Manual process 3Tape (sequential file) 4Disk 5Paper file 6 & 8Document (In or out) 7Keyboard Input 9CRT display (cptr) 10OFF page connector 11ON page connector 12Terminator (start/end) 13Batch Total 1Computer process 2Manual process 3Tape (sequential file) 4Disk 5Paper file 6 & 8Document (In or out) 7Keyboard Input 9CRT display (cptr) 10OFF page connector 11ON page connector 12Terminator (start/end) 13Batch Total 1 11 10 Processes Storage (files) InputOutputMiscell. 2 3 4 6 7 8 9 12 13 5

11. Vocabulary of DFDs Context DFD Physical DFD Logical DFD Bubble Square The System Internal Entity External Entity External Entity External Entity Process N/AFile Data Flow Data Flow Data Flow or “connector”

12. Context - bird’s eye view Customer Bank Cash Receipts system check receipt deposit

13. Physical – people (HOW) Customer Bank Mailroom check receipt deposit A/R CPTR Cashier deposit info deposit slip

14. Logical - things you do (WHAT) Customer Bank open mail check receipt deposit enter info & update files enter info & update files Prepare deposit Prepare deposit

15. Preparing Physical DFDs Identify internal and external entities Identify Activities Draw CIRCLES for internal entities and SQUARES for external entities Draw arrows between entities to represent data (either documents or other information going from one entity to another (or to or from files) It’s Easy!

16. Guidelines for DFDs Drawing the Context Diagram Guideline 1.Include within the system context (bubble) any entity that performs one or more information processing activities. Guideline 2.Include only normal processing routines not exception routines or error routines, on all DFDs (that we will do) Guideline 3.Include on the systems documentation all (and only) activities described in the system narrative - no more, no less. Guideline 4.When multiple entities operate identically, depict only one to represent all.

17. Guidelines for DFDs Drawing the Current Physical Data Flow Diagram Guideline 5.For clarity, draw a separate data flow for each flow into or out of a file. Guideline 6.If a file is logically necessary (that is, because of a delay between processes), include a file in the diagrams, whether or not it is mentioned in the narrative.

18. Guidelines for DFDs Summary of Drawing Data Flow Diagrams Guideline 11.A data flow should go to an operations entity square when only operations functions are to be performed by that entity. A data flow should enter a bubble if the operations entity is to perform an information processing activity. Guideline 12.On a physical DFD, reading computer files and writing to computer files must go through a computer bubble.

19. Table of Activities Entities and activities

20. Logical DFDs Why do we need both logical and physical DFDs?

21. Guidelines for DFDs Drawing the Current Logical Data Flow Diagram Guideline 7.Group activities if they occur in the same place and at the same time. Guideline 8.Group activities if they occur at the same time but in different places. Guideline 9.Group activities that seem to be logically related. Guideline 10.To make the DFD readable, (try to) use between three and seven bubbles. For our class, try to use between three and four bubbles.

22. Guidelines for DFDs Summary of Drawing Data Flow Diagrams Guideline 11.A data flow should go to an operations entity square when only operations functions are to be performed by that entity. A data flow should enter a bubble if the operations entity is to perform an information processing activity. Guideline 12.On a logical DFD, reading computer files and writing to computer files must go through a computer bubble. Guideline 13.On a logical DFD, data flows cannot go from higher to lower numbered bubbles.

23. Preparing Logical DFDs Take the list of activities and lightly CROSS OFF all send and receive activities (including forward, take, etc.) Crossing off sends and receives does not mean that we will ignore them. They just won’t be inside a process bubble. The easiest way to group activities is to write down the activity numbers in chronological order and find natural “breaks” in the process. CONSTRUCT the Logical DFD!

24. Preparing Logical DFDs Three Hints: 1)There should be 3 to 5 bubbles. Likely candidates include capture, record, reconcile, update, and output. 2)Never have an arrow from a higher numbered bubble to a lower numbered bubble (put in sequential order). 3) External entities and data flows are exactly the same as in the physical DFD.