E. Wainright Martin Carol V. Brown Daniel W. DeHayes Jeffrey A. Hoffer William C. Perkins MANAGINGINFORMATIONTECHNOLOGY FIFTH EDITION CHAPTER 9 (part b) B ASIC I NFORMATION S YSTEMS C ONCEPTS

© 2005 Pearson Prentice-Hall Chapter Page 366 Figure 9.10 Physical Model of a System BoxesMajor modules CylindersDatabases ArrowsFlow of data

© 2005 Pearson Prentice-Hall Chapter Page 366 Tools for the As-Is Model Must identify existing processes, external participants, other databases or applications, and inputs and outputs Tools used:   Procedures, policies, manuals, forms, reports   Other documentation   Group interviews

© 2005 Pearson Prentice-Hall Chapter Page 367 Context diagram – positions the system as a whole with regard to other entities and activities with which it interacts Work process flow diagram – identifies the existing information sources, information sources that are updated, order in which steps occur, and some of the dependencies Tools for the As-Is Model

© 2005 Pearson Prentice-Hall Chapter Page 367 Figure 9.11 Context Diagram for Accounts Payable Tools for the As-Is Model

© 2005 Pearson Prentice-Hall Chapter Page 368 Figure 9.12 Work Process Flow Diagram for Accounts Payable

© 2005 Pearson Prentice-Hall Chapter Page 367 Tools for the Logical To-Be Model High-level model of a nonexistent new system Identifies processes and data Does not identify who does activity, where accomplished, or type of hardware or software Describes “what” rather than “how” Most closely associated with data flow diagrams (DFDs)

© 2005 Pearson Prentice-Hall Chapter Page 369 Tools for the Logical To-Be Model Figure 9.13(A) Top-Level DFD for Accounts Payable System

© 2005 Pearson Prentice-Hall Chapter Page 369 Figure 9.13(A) Top-Level DFD for Accounts Payable System External Entity Data Flow Processes Data Store

© 2005 Pearson Prentice-Hall Chapter Page 369 Tools for the Logical To-Be Model Process of creating a DFD:   Identify entities that supply or use system information   Distinguish processes from data they use or produce   Explicate business rules that affect transformation of data to information   Identify logical relationships   Pinpoint duplicate storage and movement of data

© 2005 Pearson Prentice-Hall Chapter Page 370 Lower-level explosion DFD for Process 1.0

© 2005 Pearson Prentice-Hall Chapter Page 370 Figure 9.13(B) Second-Level DFD for Accounts Payable System Note process numbering scheme

© 2005 Pearson Prentice-Hall Chapter Page More logical modeling required after DFDs Need to define system’s data elements and relationships:   Data dictionary/directory (DD/D) used to define data elements   Entity-relationship diagram (ERD) used to define relationships between entities Tools for the Logical To-Be Model

© 2005 Pearson Prentice-Hall Chapter Page 371 Figure 9.14 Data Dictionary Sample Entry

© 2005 Pearson Prentice-Hall Chapter Page 372 Figure 9.15 Entity-Relationship Diagram for Invoice and PO Tools for the Logical To-Be Model

© 2005 Pearson Prentice-Hall Chapter Page 372 Figure 9.16 Key Terms for Logical Data Modeling Relational Database Terminology

© 2005 Pearson Prentice-Hall Chapter Page Tools for Documenting the Physical To-Be System Tools for physical design represent how:   processes and data stores partitioned   program control handled   database organized Tools include:   Program structure chart   Database design   System interface layouts

© 2005 Pearson Prentice-Hall Chapter Page 373 Figure 9.17 Program Structure Chart Program Structure Chart

© 2005 Pearson Prentice-Hall Chapter Page 374 Figure 9.18 Relationships for Data Elements in Accounts Payable Database Design (data relationships) (Screen shot reprinted with permission from Microsoft Corporation)

© 2005 Pearson Prentice-Hall Chapter Page 375 Figure 9.19 Input Form Layout for Vendor Invoice System Interface Input Layout Form (Screen shot reprinted with permission from Microsoft Corporation)

© 2005 Pearson Prentice-Hall Chapter Page 375 Figure 9.20 Check Register Report Layout with Sample Data Output Report Layout

© 2005 Pearson Prentice-Hall Chapter Page 374 Object-Oriented Techniques Object approach well suited for client/server applications, graphical interfaces, and multimedia data Primary advantage is ability to reuse objects programmed by others P ROCESSES AND T ECHNIQUES TO D ELIVER I NFORMATION S YSTEMS

© 2005 Pearson Prentice-Hall Chapter Page 376 Object-Oriented Techniques P ROCESSES AND T ECHNIQUES TO D ELIVER I NFORMATION S YSTEMS Figure 9.21 The Promise of Object-Oriented Approaches

© 2005 Pearson Prentice-Hall Chapter Page 376 Core Concepts P ROCESSES AND T ECHNIQUES TO D ELIVER I NFORMATION S YSTEMS Figure 9.22 Message Passing Object Encapsulation Inheritance Objects communicate with each other through messages that specify what should be done, not how it should be done

© 2005 Pearson Prentice-Hall Chapter Page 376 Unified Modeling Language (UML) For O-O Modeling P ROCESSES AND T ECHNIQUES TO D ELIVER I NFORMATION S YSTEMS Figure 9.22 Message Passing UML is standardization for O-O analysis and design modeling techniques and notations UML diagrams:   Use-case diagrams   Extended relationship use-case diagram   Sequence diagram   Class diagram Logical modeling begins with use-cases – diagrams and text forms

© 2005 Pearson Prentice-Hall Chapter Page 376 Figure 9.23 Use Case Diagram Use Case Diagram

© 2005 Pearson Prentice-Hall Chapter Page 376 Figure 9.24 Become Member Use Case Use Case – Text Form

© 2005 Pearson Prentice-Hall Chapter Page 377 I NFORMATION S YSTEMS C ONTROLS TO M INIMIZE B USINESS R ISKS Common system security risks:   Human error   Criminal acts   Due to staffing changes and project management deficiencies   Natural disasters

© 2005 Pearson Prentice-Hall Chapter I NFORMATION S YSTEMS C ONTROLS TO M INIMIZE B USINESS R ISKS Management policies Operating procedures Auditing function Types of Control Mechanisms Page

© 2005 Pearson Prentice-Hall Chapter Page 380 I NFORMATION S YSTEMS C ONTROLS TO M INIMIZE B USINESS R ISKS Controls built into the information system itself:   To maintain data integrity   Allow only authorized access   Ensure proper system operation   Protect against malfunctions, power outages, and disasters Types of Control Mechanisms

© 2005 Pearson Prentice-Hall Chapter Page 380 I NFORMATION S YSTEMS C ONTROLS TO M INIMIZE B USINESS R ISKS IS Organization  Backup power supplies  Network access control  Firewall protection Business Organization  Ensure accurate data entry and handling  Identify procedural errors Types of Control Mechanisms

© 2005 Pearson Prentice-Hall Chapter Page 380 Types of Control Mechanisms Figure 9.26 Pre- and Post-Installation Controls INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS