MANAGING INFORMATION TECHNOLOGY FIFTH EDITION CHAPTER 9 (part b) BASIC INFORMATION SYSTEMS CONCEPTS E. Wainright Martin Carol V. Brown Daniel W. DeHayes Jeffrey A. Hoffer William C. Perkins © 2005 Pearson Prentice-Hall Chapter 9 - 2 Boxes Major modules Cylinders Databases Arrows Flow of data Figure 9.10 Physical Model of a System 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 9 - 3 Page 366 Tools for the As-Is Model 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 © 2005 Pearson Prentice-Hall Chapter 9 - 4 Page 367 Tools for the As-Is Model © 2005 Pearson Prentice-Hall Chapter 9 - 5 Figure 9.11 Context Diagram for Accounts Payable Page 367 © 2005 Pearson Prentice-Hall Chapter 9 - 6 Figure 9.12 Work Process Flow Diagram for Accounts Payable Page 368 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 9 - 7 Page 367 Tools for the Logical To-Be Model © 2005 Pearson Prentice-Hall Chapter 9 - 8 Figure 9.13(A) Top-Level DFD for Accounts Payable System Page 369 Data Flow Processes External Entity Data Store © 2005 Pearson Prentice-Hall Chapter 9 - 9 Figure 9.13(A) Top-Level DFD for Accounts Payable System 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 9 - 10 Page 369 Lower-level explosion DFD for Process 1.0 © 2005 Pearson Prentice-Hall Chapter 9 - 11 Page 370 Note process numbering scheme © 2005 Pearson Prentice-Hall Chapter 9 - 12 Figure 9.13(B) Second-Level DFD for Accounts Payable System Page 370 Tools for the Logical To-Be Model 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 © 2005 Pearson Prentice-Hall Chapter 9 - 13 Page 371-372 © 2005 Pearson Prentice-Hall Chapter 9 - 14 Figure 9.14 Data Dictionary Sample Entry Page 371 Tools for the Logical To-Be Model © 2005 Pearson Prentice-Hall Chapter 9 - 15 Figure 9.15 Entity-Relationship Diagram for Invoice and PO Page 372 Relational Database Terminology © 2005 Pearson Prentice-Hall Chapter 9 - 16 Figure 9.16 Key Terms for Logical Data Modeling Page 372 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 9 - 17 Page 372-373 Program Structure Chart © 2005 Pearson Prentice-Hall Chapter 9 - 18 Figure 9.17 Program Structure Chart Page 373 Database Design (data relationships) (Screen shot reprinted with permission from Microsoft Corporation) © 2005 Pearson Prentice-Hall Chapter 9 - 19 Figure 9.18 Relationships for Data Elements in Accounts Payable Page 374 System Interface Input Layout Form (Screen shot reprinted with permission from Microsoft Corporation) © 2005 Pearson Prentice-Hall Chapter 9 - 20 Figure 9.19 Input Form Layout for Vendor Invoice Page 375 Output Report Layout © 2005 Pearson Prentice-Hall Chapter 9 - 21 Figure 9.20 Check Register Report Layout with Sample Data Page 375 PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS 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 © 2005 Pearson Prentice-Hall Chapter 9 - 22 Page 374 PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Object-Oriented Techniques © 2005 Pearson Prentice-Hall Chapter 9 - 23 Figure 9.21 The Promise of Object-Oriented Approaches Page 376 PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Core Concepts 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 9 - 24 Figure 9.22 Message Passing Page 376 PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Unified Modeling Language (UML) For O-O Modeling 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 9 - 25 Figure 9.22 Message Passing Page 376 Use Case Diagram © 2005 Pearson Prentice-Hall Chapter 9 - 26 Figure 9.23 Use Case Diagram Page 376 Use Case – Text Form © 2005 Pearson Prentice-Hall Chapter 9 - 27 Figure 9.24 Become Member Use Case Page 376 INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Common system security risks: Human error Criminal acts Due to staffing changes and project management deficiencies Natural disasters © 2005 Pearson Prentice-Hall Chapter 9 - 28 Page 377 INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Types of Control Mechanisms Management policies Operating procedures Auditing function © 2005 Pearson Prentice-Hall Chapter 9 - 29 Page 378-380 INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Types of Control Mechanisms 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 © 2005 Pearson Prentice-Hall Chapter 9 - 30 Page 380 INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Types of Control Mechanisms IS Organization Backup power supplies Network access control Firewall protection © 2005 Pearson Prentice-Hall Chapter 9 - 31 Business Organization Ensure accurate data entry and handling Identify procedural errors Page 380 INFORMATION SYSTEMS CONTROLS TO MINIMIZE BUSINESS RISKS Types of Control Mechanisms © 2005 Pearson Prentice-Hall Chapter 9 - 32 Figure 9.26 Pre- and Post-Installation Controls Page 380