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IS 630 : Accounting Information Systems Systems Documentation: Systems Flowchart & Data Flow Diagram Lecture.

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Presentation on theme: "IS 630 : Accounting Information Systems Systems Documentation: Systems Flowchart & Data Flow Diagram Lecture."— Presentation transcript:

1 IS 630 : Accounting Information Systems Systems Documentation: Systems Flowchart & Data Flow Diagram Lecture 3

2 System Documentation  System Flowcharts present a comprehensive picture of the management, operations, information systems, and process controls embodied in business processes.  Data Flow diagrams (DFD) portray a business process activities, stores of data, and flows of data among those elements. IS 630 : Lecture 32

3 Systems Flowcharts  Systems Flowchart: a graphical representation of a business process, including information processes (inputs, data processing, data storage, and outputs), as well as the related operations processes (people, equipment, organization, and work activities).  ( Also known as “process flowcharts” and “business process flowcharts”, “document flowcharts”) IS 630 : Lecture 33

4 Standard Flowcharting Symbols IS 630 : Lecture 34

5 Common System Flowcharting Routines Enter document into computer via keyboard, edit input, record input. (Note that columns are set up to communicate the flow of activities between processing entities.) IS 630 : Lecture 3 5

6 Common System Flowcharting Routines … User queries the computer IS 630 : Lecture 3 6

7 Common System Flowcharting Routines... Update sequential data store IS 630 : Lecture 3 7

8 Common System Flowcharting Routines... Preparation and then manual reconciliation of control totals. IS 630 : Lecture 3 8

9 Common System Flowcharting Routines... Key and rekey to verify inputs IS 630 : Lecture 3 9

10 Common System Flowcharting Routines... Enter document into computer using a scanner IS 630 : Lecture 3 10

11 Common System Flowcharting Routines... Enter document into computer using scanner and then manual keying IS 630 : Lecture 3 11

12 Preparing Systems Flowcharts 1.Divide the flowchart into columns (areas of responsibilities): 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, minimize crossed lines and connectors. 3.Flowchart logic should flow from top to bottom and from left to right. For clarity, put arrows on all flow lines. IS 630 : Lecture 312

13 Preparing Systems Flowcharts... 4.Keep the flowchart on one page, if possible. With multiple pages use off-page connectors. 5.Within each column, there must be at least one manual process, keying operation, or data store between documents. 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. IS 630 : Lecture 313

14 Preparing Systems Flowcharts... 7.Documents or reports printed in a computer facility should be shown in that facility’s column first. 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 should not be shown within the computer facility. IS 630 : Lecture 314

15 Preparing Systems Flowcharts... 9.Processing within an organizational unit on devices such as a PC, laptop, 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. IS 630 : Lecture 315

16 Preparing Systems Flowcharts The only way to get data into or out of a computer data storage unit is through a computer processing rectangle or offline process square. 12.Manual process is not needed to show the sending of a document; sending should be apparent from the movement of the document. 13.Do not use manual processes to file documents; show documents going into files. IS 630 : Lecture 316

17 Preparing Systems Flowcharts...  All documents must have an origin and termination: each copy of the document must flow to a permanent file symbol a symbol denoting an exit from the system, or an off-page connector a document destruction symbol (small black box) “cradle to grave” documentation  Make sure progress of a document is clear. Diagram a document before and after each process entering or leaving a file entering or leaving a page or area of responsibility IS 630 : Lecture 317

18 Suprina Systems Flowchart IS 630 : Lecture 318

19 Documenting Enterprise Systems  Moving from a file-based system to an enterprise database changes the systems flowchart. An enterprise database replaces transaction and master data. Other flows may change depending on the system implementation. IS 630 : Lecture 319

20 Suprina Systems Flowchart with an Enterprise Database IS 630 : Lecture 320

21 Flowchart Summary The flowchart is one of the easier types of documentation for information customers and management to understand. Often, auditors use system, document, and procedure flowcharts to understand business and systems controls in an environment The primary weakness of the flowchart is that it is tied to physical information flows and system characteristics that hide the procedural essence of the system. Some flowcharts are full of data and processing artifacts because they are tied to an outdated information technology. IS 630 : Lecture 321

22 IS 630 : Lecture 322 Process Modeling / Documentation  Logical vs. Physical Models  System and Process Concepts  Data Flow Diagrams (DFD)  Elements of a DFD  Rules and Procedures in DFD

23 23 External Entity Data Flow Process Data Store DE MARCO & YOURDON Data Flow Diagrams Symbols IS 630 : Lecture 3

24 24 External Entity Data Flow Process Data Store GANE & SARSON NOTATIONS Pay Bill AP Clerk 3 Data Flow Diagrams Symbols IS 630 : Lecture 3

25 25 Why System Modeling  To better understand the system: opportunities for simplification, optimization (BPR)  To communicate the desired structure and behavior of the system (business requirements: data/information & functions/processes)  To visualize and control the system architecture (blueprint)  To manage risks in development process

26 IS 630 : Lecture 326 Logical Vs. Physical Models Logical models show WHAT a system is or does. They are independent of any technical implementation. Physical models show not only what a system is or does, but also HOW the system is (to be) physically and technically implemented. They reflect technology choices.

27 IS 630 : Lecture 327 Why Logical Models  Logical models remove (political, emotional) biases resulted from the way the system is currently implemented, or the way that any one person thinks the system might be implemented.  Logical models reduce the risk of missing business requirements in cases one is too preoccupied with technical results (premature technical solutions).  Logical models allow the communication with end-users in nontechnical or less technical languages (charts, diagrams).

28 IS 630 : Lecture 328 Process Modeling with DFD  Process Modeling is a technique for organizing and documenting the structure and flow of data through a system’s processes, and the logic, policies, and procedures to be implemented by a system’s processes.  Data Flow Diagram (DFD) is a graphical tool to depict the flow of data through a system and the work or processing performed by that system.  Language description (memo) is subject to interpretation, it may omit crucial info.  DFD is Graphical description the flows of data within an organization

29 IS 630 : Lecture 329 System Concept  A system exits by taking input from the environment, transforming (processing) this input, and release an output  A system may be decomposed (exploded) into subsystems  A subsystem has its own input and output  Output of one subsystem may become the input of other subsystems (throughput)

30 30 Systems & Subsystems INPUTOUTPUT IS 630 : Lecture 3

31 31 Systems & Processes  A system is a process. It addresses a business function.  A process is work / action performed on, or in response to, incoming data flows or conditions.  A process (function) can be decomposed into sub-processes (sub-functions, tasks)

32 IS 630 : Lecture 332 Decomposition Diagram

33 IS 630 : Lecture 333 Functional Decomposition Diagram

34 IS 630 : Lecture 334 Event Decomposition Diagram

35 IS 630 : Lecture 335 Data Flow Diagrams  DFD documents a business function/activity/task of a system as a process.  DFD describes how data is manipulated within and at the boundaries of the system.  DFD shows detail of the interdependency among processes of the system, movements of data or info among the processes.

36 IS 630 : Lecture 336 External Entities  An External Entity is a provider (source) or receiver (sink) of data and info of the system.  An External Entity is NOT part of the system: the externality depends on how the system is defined. SUPPLIER

37 IS 630 : Lecture 337 External Entities...  An external entity (agent) defines a person, organization unit, or other organization that lies outside of the scope of the project but that interacts with the system being studied. External agents define the “boundary” or scope of a system being modeled. As scope changes, external agents can become processes, and vice versa. Almost always one of the following: o Office, department, division inside the business but outside the system scope. o An external organization or agency. o Another business or another information system. o One of system’s end-users or managers

38 IS 630 : Lecture 338 Data Stores  A Data Store is a storage of data: it contains information  Physical storage is immaterial : it can be a filing cabinet, book, computer file D1 Accounts Receivable

39 IS 630 : Lecture 339 Data Stores...  A data store is an inventory of data. A data store is “data at rest” compared to a data flow that is “data in motion.” Almost always a data store for one of the following: o Persons (or groups of persons): e.g., customer o Places: e.g, cash register o Objects: e.g., product o Events (about which data is captured): e.g., sales o Concepts (about which data is important): e.g., discount One can identify data stores with REAL (Resources-Events- Agents-Locations) framework Data stores depicted on a DFD store all instances of data entities (depicted on an ERD)

40 IS 630 : Lecture 340 Data Flows  A Data Flow represents a movement of data ( info ) among processes or data stores  A Data Flow does NOT represent a document or a physical good: it represents the exchange of information in the document or about the good  A Data Flow represents an input of data to a process, or the output of data from a process. A data flow may also be used to represent the creation, reading, updating, or deletion (CRUD) of data in a file or database (called a data store). A composite data flow (packet) is a data flow that consists of other data flows. DELIVERY SLIP

41 IS 630 : Lecture 341 Processes  A Process is a work or action performed on input data flow to produce an output data flow  Use a verb to label the action performed by the process (not the name of person or department who does it as in physical DFD)  A Process must have at least one input data flow and at least one output data flow. 1 Pay Bill

42 IS 630 : Lecture 342 Types of Processes  Function : a set of related and ongoing activities of a business: e.g., sales.  Activity (Event / Transaction) : a logical unit of work that must be completed as a whole (as part of a function): e.g., collect payment.  Task (Elementary / Primitive Process): a discrete, detailed activity or task required to respond to an event. Usually, several such tasks must be completed to respond to an activity/ event, e.g, update new info, calculate payment, create notice…

43 IS 630 : Lecture 343 Context Diagram  Define the boundary of the system  Identify the external entities  No detail on processes and data stores of the system

44 IS 630 : Lecture 344 M N P M N P Context Diagram Level-0 Diagram Level-1 Diagram D1

45 IS 630 : Lecture 345 DFD Building Procedure  Context Diagram Identify the system and its boundaries (the context) Identify external entities (providers, receivers of system info) Identify external data flows (input, output) Note: the whole system itself is a process (it receives input and transforms it into output) doing a business function

46 IS 630 : Lecture 346 DFD Building Procedure...  Level-0 DFD Identify what is being done between each input and its corresponding output Identify the processes ( functions of the system) Identify external data flows between external entities and processes Identify internal data flows between processes and data stores  Level-1 DFD’s Sub-processes ( activities or tasks ) of Level-0 processes (system functions)

47 IS 630 : Lecture 347 Rules in DFD Building  Rule 1 : Unique label for each symbol to avoid confusion  Rule 2 : Use an action VERB to label a process (because a process is an action !!!)

48 IS 630 : Lecture 348 Rules in DFD Building...  Rule 3 : Must be one process associated with each data flow … M M

49 IS 630 : Lecture 349 Rules in DFD Building...  Rule 3 : Must be one process associated with each data flow … MN MN

50 IS 630 : Lecture 350 Rules in DFD Building...  Rule 3 : Must be one process associated with each data flow.

51 IS 630 : Lecture 351 Rules in DFD Building...  Rule 4 : Shaded corner must appear in ALL occurrences of a duplicated symbol in a same diagram on the same page. CUSTOMER D3 Accounts Receivable

52 IS 630 : Lecture 352 Rules in DFD Building...  Rule 5 : No process without output data flow (black hole !!!)

53 IS 630 : Lecture 353 Rules in DFD Building...  Rule 6 : No process without input data flow (miracle !!!)

54 IS 630 : Lecture 354 Rules in DFD Building...  Rule 7 : No need for routing (without transforming) a data flow with a process (non value-added activities !!!) Info A

55 IS 630 : Lecture 355 Rules in DFD Building...  Rule 8 : Identical input, output data flows for parent and child processes (but the child processes can have their own throughputs). Balance Check.

56 IS 630 : Lecture 356 M N P M N P Context Diagram Level-0 Diagram Balance Check

57 IS 630 : Lecture 357 Rules in DFD Building...  Rule 9 : Data flows cannot split by themselves

58 IS 630 : Lecture 358 Rules in DFD Building...  Rule 9 : Data flows cannot split …

59 IS 630 : Lecture 359 Rules in DFD Building...  Rule 10 : A data packet can combine many data elements being transmitted at the same time to the same destination (a document carries many pieces of info)

60 IS 630 : Lecture 360 Rules in DFD Building...  Rule 11 : Double-headed arrows are forbidden [in- flow (update) and out-flow (extract info) of a data store carry different information]

61 IS 630 : Lecture 361 Rules in DFD Building...  Rule 12 : Data flow can NOT go backward in Level-0 (Today’s output can’t go back to yesterday’s work !!!) Notes: Show any branching decision / loop in Level-1

62 IS 630 : Lecture 362 Differences Between DFDs and Flowcharts  Processes on DFDs can operate in parallel (at-the- same-time) Processes on flowcharts execute one at a time  DFDs show the flow of data through a system Flowcharts show the flow of control (sequence and transfer of control)  Processes on a DFD can have different timing (daily, weekly, on demand) Processes on flowcharts are part of a single program with consistent timing

63 IS 630 : Lecture 363 Data Conservation Data conservation – the practice of ensuring that a data flow contains only data needed by the receiving process. New emphasis on business process redesign to identify and eliminate inefficiencies. Simplifies the interface between those processes. Must precisely define the data composition (attributes/fields) of each data flow (document), expressed in the form of data structures (in Data Modeling). “cradle to grave” documentation CRUD Matrix : C reate, R ead, U pdate, D elete.

64 IS 630 : Lecture 364 Data to Process Matrix

65 © 2010 CSUN 65 Architecture Blueprints Street LocationContext Diagram 0 E1E2 N IS 630 : Lecture 3

66 66 Architecture Blueprints... F1 F2 F3 Building Plan Level-0 DFD E1 E2 The building has 3 floorsThe system has 3 functions © 2010 D. CSUN

67 IS 630 : Lecture 367 Floor Plan for F1 Level-1 DFD for 1.0 Architecture Blueprints... Floor 1 has a big space for parking Function 1 has a single task 1.0 No need for Level-1 (can get from Level-0) No need for detail blueprint © 2010 D. CSUN

68 IS 630 : Lecture Floor Plan for F2Level-1 DFD for (3.0) Architecture Blueprints... Floor 2 has 3 suites Function 2 has 3 activities (1.0) © 2010 D. CSUN

69 IS 630 : Lecture Suite Plan for 2.1Level-2 DFD for (2.2) Architecture Blueprints... Suite 2.1 has 2 rooms Activity 2.1 has 2 tasks © 2010 D. CSUN (1.0)

70 Linked Processes D1 1.0 sends data to and 2.0 share the same data store D1 IS 630 : Lecture 370

71 IS 630 : Lecture (EXTRA STEP) (CONDITIONAL EXIT) IF (Condition) DO “1.2” IF (Condition) DO “2.2” ELSE DO “2.3” (2.0)(3.0) Note: Show conditional branching in Level-1 DFD’s or lower. Conditional Branching

72 IS 630 : Lecture 372 DFD Deliverables  Current System Context Diagram Logical Level-0 DFD Logical Level-1 DFD’s (multi-task functions) Physical Level-0 DFD [for AUDITING] Physical Level-1 DFD’s (multi-task functions) [for AUDITING]  Proposed System Context Diagram Logical Level-0 DFD Logical Level-1 DFD’s (multi-task functions) Physical Level-0 DFD [for implementation] Physical Level-1 DFD’s (multi-task functions)[for implementation]


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