1. Documenting Information Systems

2. Learning Objectives To read and evaluate data flow diagrams To read and evaluate systems flowcharts. To prepare data flow diagrams from a narrative. To prepare systems flowcharts from a narrative. Documenting Information Systems

3. 3 Documenting Processes on the AIS Wheel Process documentation is a important skill in accounting You will learn that data flow diagrams portray a business processes’ activities, stores of data, and flows of data among those elements. Systems flowcharts, on the other hand, present a comprehensive picture of the management, operations, information systems, and process controls embodied in business processes.

4. 4 Basic DFD Symbols

5. 5 Context Diagram One Process –Describes System / Process At least one Entity –Outside of System / Process At least one Source & one Sink

6. 6 Logical DFD A logical data flow diagram is a graphical representation of a system showing the system’s processes (as bubbles), data stores, and the flows of data into and out of the processes and data stores. –We use a logical DFD to document information systems because we can represent the logical nature of a system— what tasks the system is doing— without having to specify how, where, or by whom the tasks are accomplished. –The advantage of a logical DFD (versus a physical DFD) is that we can concentrate on the functions that a system performs. –So, a logical DFD portrays a system’s activities, whereas a physical DFD depicts a system’s infrastructure. –We need both pictures to understand a system completely.

7. 7 Logical DFD

8. 8 Data Flow Diagrams Logical model of ? –Data gathered from requirements determination RD determined what? –What the new system should do AND –What the old system does Depiction of processes and data flows of a system

9. 9 Benefits of DFD’s Uncover misunderstandings of system processes Help communicate analyst system understanding to management/end users Helps to take the system out of context –Eases the problem of thinking outside of the box

10. 10 Context-Level Diagram 0 Employee Payroll System Employee Tax Form Payroll Report Time Sheet Employee Payroll Check Employee Accounting Department

11. 11 Level-0 DFD 1.0 Create Weekly Payroll Record Employee Data File S1 Employee Payroll Data File S2 2.0 Compute Weekly Paycheck 3.0 Prepare Weekly Payroll Summary 4.0 Prepare Employee Tax Form Accounting Department Employee RecordPaycheck Data Payroll Record Payroll Report Employee Paycheck Employee Tax Form Time Sheet Hours Worked Employee Payroll Record

12. 12 Level-1 DFD 1.0 Create Weekly Payroll Record Employee Data File S1 Employee Tax Form Payroll Data File S2 2.1 Compute Gross Pay 2.3 Create Payroll Check 2.2 Compute Net Pay 3.2 Print Weekly Payroll Summary 3.1 Sort Payroll Records by Employee 4.2 Print Employee Tax Form 4.1 Calculate Payroll Deductions Employee Paycheck Payroll Deductions Employee Payroll Record Time Sheet Employee Record Gross Pay Data Net Pay Data Hours Worked Payroll Record Sorted Records Payroll Report Employee Accounting Department

13. 13 How low Can you go?

14. 14 Functional Primitive 4.1.2 Calculate Non-tax Deductions 4.1.3 Calculate Retirement Allowance 4.2.1 Calculate Employee Vacation Pay 4.1.1 Calculate Payroll Tax Deductions 4.2.2 Print Employee Tax Form Employee Data Employee Data Employee Data Employee Tax Form Employee Payroll Record Employee Data

15. 15 Balanced DFDs The next slide depicts “balanced” data flow diagrams. Balanced DFDs exist when the external data flows are equivalent. DFD (a) is a context diagram and (b) is an “explosion” of it into a level 0 logical DFD. DFD (c), (d) and (e) are “explosions” of the logical level 0 DFD, and so on.

16. 16 Balanced DFDs

17. 17 The Rules of DFDs In a nutshell… All data flows must begin and/or end at a process, because data flows either initiate or result from a process.

18. 18 Rules Governing DFD Construction A process cannot have only outputs – “miracle.” A process cannot have only inputs – “black hole.” The inputs to a process must be sufficient to produce the outputs from the process - (gray hole). All data stores must be connected to at least one process.

19. 19 Rules Governing DFD Construction A data store cannot be connected to a source or sink. A data flow can have only one direction of flow. Multiple data flows to and/or from the same process and data store must be shown by separate arrows. If the exact same data flows to two separate processes, it should be represented by a forked arrow. Data cannot flow directly back into the process it has just left. All data flows must be named using a noun phrase.

20. 20 Three Basic Illegal Data Flows Black Hole Miracle Gray Hole EntityName Identifier ProcessName Identifier ProcessName FileName Employee 1.0 CreateEmployeePaychecks EmployeeFile

21. 21 Other Illegal Flows EmployeeFile D1 OrderFile D2 Data Must Be Connected to a Process Employee 1.0 CreateEmployeePaychecks No Bi-Directional Flows Customer CustFile D1

22. 22 One Final Illegal Flow 2.1.0 2.1.0 ProcessName Data Cannot Flow Directly Back Into The Process It Left

23. 23 A Debate 2.2.0 2.2.0 Process 2.3.0 2.3.0 Process 2.1.0 2.1.0 Process 2.2.0 2.2.0 Process 2.3.0 2.3.0 Process 2.1.0 2.1.0 Process Which is Right?

24. 24 Balancing Data Flows Source 1.0 FormatData Sink 2.0 SendReports Source2 A Formatted A Formatted C C B Source 0 ContextLevelSystem Sink A B A B Source 0 ContextLevelSystem Sink Source2 C

25. 25 Preparing Data Flow Diagrams Read narrative carefully - number lines and paragraphs in text Prepare table of entities and activities Draw context diagram - use DFD guidelines

26. 26 DFD Guidelines 1. Include within the system context (bubble) any entity that performs one or more information processing activities. 2. For now, include only normal processing routines, not exception routines or error routines, on context diagrams, physical DFDs, and logical level 0 DFDs. 3. Include on the systems documentation all (and only) activities and entities described in the systems narrative - no more, no less. 4. When multiple entities operate identically, depict only one to represent all.

27. 27 Causeway Context Diagram

28. 28 DFD Guidelines (cont.) 5. For clarity, draw a data flow for each flow into and out of a data store. You may, also for clarity to help you determine that you have included all necessary flows, label each flow with the activity number that gives rise to the flow or with a description of the flow. 6. If a data store is logically necessary (that is, because of a delay between processes), include a data store in the diagrams, whether or not it is mentioned in the narrative.

29. 29 DFD Guidelines (cont.) 7. Group activities if they occur in the same place and at the same time. 8. Group activities if they occur at the same time but in different places. 9. Group activities that seem to be logically related. 10. To make the DFD readable, use between five and seven bubbles.

30. 30 Causeway Logical Level 0 DFD

31. 31 DFD Guidelines (cont,) 11. A data flow should go to an operations entity square only when operations process functions (that is, work- related functions such as storing goods, picking goods from shelves, packing the customer’s order and so on) are to performed by that entity. A data flow should enter an entity bubble if the operations process entity is to perform an information processing activity. 12. On a physical DFD, reading computer data stores and writing to computer data stores must go through a computer bubble. 13. On a logical DFD, data flows cannot go from higher- to lower-numbered bubbles.

32. 32 Standard Flowchart Symbols

33. 33 Common system flowcharting routines The following slides show several common ways of showing processing using system flowcharting. Pay particular attention to the way the columns are set up to communicate the flow of activities between processing entities.

34. 34 The data-entry clerk keys in an input document into the computer. The computer accesses data in a data store 1 and in data store 2 to edit/validate the input. The computer displays the input, including any errors. The clerk compares the input document to the display, keys corrections as necessary, and accepts the input. The computer updates the table in data store 2 and notifies the clerk that the input has been recorded.

35. 35 User queries the computer. The computer accesses the table(s) in one of more data stores & presents a response to the user. Update sequential data store from magnetic disk are input to the computer, along with the existing (old) master data – becoming the new master data

36. 36 The user batches the input documents, prepares batch totals, and keys the documents into the computer. The computer records the inputs on disk and notifies the user as each input is accepted. The user files the input documents in numerical sequence. At the end of the batch, the computer prepares an exception & summary report that includes batch totals. The user compares the computer batch totals to those prepared earlier.

37. 37 A data entry clerk enters documents into a networked PC system. The system records the inputs on a disk and notifies the user of the acceptance of each input. The documents are then forwarded to a different clerk who keys the documents again. Differences are resolved and the event data are updated to reflect the verifications and corrections.

38. 38 A clerk scans a document into the computer. Use the data from the scanned document, the computer updates the data store(s)

39. 39 A clerk scans a document into the computer. The computer routes an image of the scanned input to a data entry clerk, who keys data from the documents image into the computer. The computer records the data with the scanned document

40. 40 Preparing Systems Flowcharts 1. Divide the flowchart into columns; one column for each internal entity and one for each external entity. Label each column. 2. Flowchart columns should be laid out so that the flowchart activities flow from left to right, but you should locate columns so as to minimize crossed lines and connectors.

41. 41 System flowcharting guidelines (cont.) 3. Flowchart logic should flow from top to bottom and from left to right. For clarity, put arrows on all flow lines. 4. Keep the flowchart on one page. If you can’t, use multiple pages and connect the pages with off-page connectors. Computerized flowcharting packages will print your flowcharts only on paper that will fit in your printer!

42. 42 Causeway’s Systems Flowchart The systems flowchart for Causeway follows on the next slide This flowchart for causeway is without an enterprise database

43. 43

44. 44 System flowcharting guidelines (cont.) 5. Within each column, there must be at least one manual process, keying operation, or data store between documents. That is, do not directly connect documents within the same column. 6. When crossing organizational lines (one column to another), show a document at both ends of the flow line unless the connection is so short that the intent is unambiguous.

45. 45 System flowcharting guidelines (cont.) 7. Documents or reports printed in a computer facility should be shown in that facility’s column first. You can then show the document or report going to the destination unit. 8. Documents or reports printed by a centralized computer facility on equipment located in another organizational unit ( warehouse, shipping dept.) should not be shown within the computer facility.

46. 46 System flowcharting guidelines (cont.) 9. Processing within an organizational unit on devices such as a PC or computerized cash register should be shown within the unit or as a separate column next to that unit, but not in the central computer facility column. 10. Sequential processing steps (computerized or manual) with no delay between them (and resulting from the same input) can be shown as one process or as a sequence of processes.

47. 47 System flowcharting guidelines (cont.) 11. The only way into a computer data storage unit is through a computer processing rectangle. 12. A manual process is not needed to show the sending of a document. The sending of the document should be apparent from the movement of the document itself. 13. Do not use a manual process to file a document. Just show the document going in to a file.

48. 48 Causeway’s Systems Flowchart The systems flowchart for Causeway is presented again on the next slide This flowchart for causeway is again presented without an enterprise database

49. 49

50. 50 Documenting Enterprise Systems Moving from a file-based system to an enterprise database changes the system flowchart –An enterprise database replaces transaction and master data –Other flows may change depending on the system implementation

51. 51 Causeway’s Systems Flowchart The systems flowchart for Causeway follows on the next slide This flowchart for causeway is with an enterprise database

52. 52