Chapter 3 Systems Documentation Techniques Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall 3-1

Learning Objectives  Prepare and use data flow diagrams to understand, evaluate, and document information systems.  Prepare and use flowcharts to understand, evaluate, and document information systems. Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall 3-2

What is Documentation?  Set of documents and models  Narratives, data flow model, flowcharts  Describe Who, What, Why, When & Where of Systems:  Input, Process, Storage, Output and Controls Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-3

Why should you learn documentation?  You need to be able to read documentation in all its forms: Narratives, diagrams, models.  You need to be evaluate the quality of systems, such as Internal Control based in part on documentation.  SAS 94: requires independent auditors understand all internal control procedures  Documentation assists in auditor understanding and documentation of their understanding  Sarbanes-Oxley states that management:  Is responsible for Internal Control System  Is responsible for assessing the effectiveness of the IC System  Both management and external auditors need to document and test IC System Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-4

Data Flow Diagrams  Graphically describes the flow of data within a system  Four Basic elements Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-5 Entity Process Data Flow Data Store

Entity  Represents a Source of Data or Input into the System and/or  Represents a Destination/Sink of Data or Output from the System  Entities exist outside of the system or process being modeled. Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-6

Data Flows  Movement of Data between:  Entities (Sources and/or Destinations)  Processes  Data Stores  Label should describe the information moving Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-7

Process  Represents the Transformation of Data Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-8

Data Store  Represents Data at Rest Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-9

Data Flow Diagram Levels  Context  Highest Level (Most General)  Purpose: Show Inputs & Outputs into/from System  Characteristics: One Process Symbol only, No Data Stores  Level-0  Purpose: Show all major activity steps of a system  Characteristics: Processes are labeled 1.0, 2.0, etc. Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-10

15 DFD Levels  DFD models are organized in a series of levels so that each level provides successively more detail about a portion of the level above  Top Level: Context Diagram  consists of only one bubble representing the entire system  the data flows show the interfaces between the system and the external entities  Successive Levels:  Figure/Level-0  highest-level view of the major functions within the system  the major interfaces between those functions  Level-1 ...  Level n

16 How Many Levels should you have?  each DFD figure should have no more than half a dozen bubbles and related stores.  Simple Systems  2-3 Levels  Medium Sized System  3-6 Levels  Large System  5-8 Levels

Context Diagram Must have at least one input and one output Does not include Data Stores Represents all the Inputs into and Outputs from the system Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-13

Level - 0 Represents each main activity of process being modeled Process numbering indicates when each activity occurs Should include data stores Number of Inputs and Outputs must be the same as in the Context Diagram Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-14

DFD Creation Guidelines  Understand the System  Ignore Certain Aspects of the System  Determine System Boundaries  Develop a Context DFD  Identify Data Flows  Group Data Flows  Number each Process  Identify transformational processes  Group transformational processes  Identify all Data Stores  Identify All Sources and Destinations  Label all DFD elements  Subdivide DFD Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-15

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

31 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

32 One Final Illegal Flow ProcessName Data Cannot Flow Directly Back Into The Process It Left

33 A Debate Process Process Process Process Process Process Which is Right?

Flowcharts  Use symbols to logically depict transaction processing and the flow of data through a system.  Using a pictorial representation is easier to understand and explain vs. a detailed narrative. Copyright 2012 Pearson Education, Inc. publishing as Prentice Hall 20

Flowchart Symbol Categories  Input/Output  Processing  Storage  Miscellaneous Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-21

Flow Chart Symbol Categories  (cont’d) Copyright © 2012 Pearson Education, Inc. publishing as Prentice Hall

Types of Flowcharts  Document  Illustrates the flow of documents through an organization.  Useful for analyzing Internal Control procedures.  System  Logical representation of System Inputs, Processes and Outputs  Useful in Systems Analysis and Design  Program  Represent the logical sequence of program logic Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-23

Document Flowchart Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-24

System Flowchart Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-25

Program Flowchart Copyright 2012 © Pearson Education, Inc. publishing as Prentice Hall 3-26