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Appraise System Building

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  • 1. 12.1 12. APPROACHES TO SYSTEMS-BUILDING
  • 2.
    • APPRAISE SYSTEM BUILDING ALTERNATIVES
    • COMPARE STRENGTHS, WEAKNESSES OF APPROACHES
    • ASSESS SOLUTIONS TO PROBLEMS CREATED BY APPROACHES
    • DESCRIBE TOOLS, METHODOLOGIES OF SYSTEMS DEVELOPMENT
    • *
    LEARNING OBJECTIVES 12.2
  • 3. MANAGEMENT CHALLENGES
    • TRADITIONAL SYSTEMS LIFECYCLE
    • ALTERNATIVE SYSTEM-BUILDING APPROACHES
    • SYSTEM-BUILDING METHODOLOGIES & TOOLS
    • *
    12.3
  • 4. SYSTEM LIFECYCLE
    • PROJECT DEFINITION: Is there a problem? Can it be solved with a project?
    • SYSTEM STUDY: Analyze problems in existing systems; define objectives evaluate alternatives
    • DESIGN: Logical & physical specifications for systems solution
    • PROGRAMMING: Develop software code
    • *
    12.4
  • 5. SYSTEM LIFECYCLE
    • INSTALLATION: Construct, test, train, convert to new system
    • POSTINSTALLATION: On-going evaluation, modifications for improvement to meet new requirements
    • NECESSARY FOR LARGE, COMPLEX SYSTEMS & PROJECTS
    • *
    12.5
  • 6. SYSTEM LIFECYCLE
    • CAN BE COSTLY, TIME CONSUMING
    • MAY ENCOURAGE FREEZING SPECIFICATIONS EARLY IN DEVELOPMENT
    • MAY NOT BE SUITABLE FOR SMALL, LESS STRUCTURED SYSTEMS
    • *
    12.6
  • 7. ALTERNATIVE SYSTEM-BUILDING APPROACHES
    • PROTOTYPING
    • APPLICATION SOFTWARE PACKAGES
    • END-USER DEVELOPMENT
    • OUTSOURCING
    • *
    12.7
  • 8. PROTOTYPING
    • PROCESS OF BUILDING EXPERIMENTAL SYSTEM TO DEMONSTRATE, EVALUATE APPROACH; USERS REFINE NEEDS
    • PROTOTYPE: Preliminary working version of information system for demonstration, evaluation purposes
    • ITERATIVE PROCESS
    • *
    12.8
  • 9. STEPS IN PROTOTYPING
    • 1. IDENTIFY USER’S REQUIREMENTS
    • 2, DEVELOP PROTOTYPE
    • 3, USE PROTOTYPE
    • 4. REVISE & ENHANCE PROTOTYPE
    • BEST FOR DESIGN OF END-USER INTERFACE: How end-user interacts with system
    • *
    12.9
  • 10. APPLICATION SOFTWARE PACKAGES
    • PREWRITTEN, PRECODED APPLICATION SOFTWARE, COMMERCIALLY AVAILABLE FOR SALE OR LEASE
    • GEARED TO COMMON REQUIREMENTS
    • CUSTOMIZATION: Modification of software to meet organization’s needs
    • MUST WEIGH COSTS / BENEFITS
    • *
    12.10
  • 11. SELECTED EXAMPLES OF APPLICATION PROGRAMS
    • ACCOUNTS RECEIVABLE; BOND & STOCK MANAGEMENT; COMPUTER-AIDED DESIGN (CAD) ; DOCUMENT IMAGING; E- MAIL; ENTERPRISE . RESOURCE PLANNING (ERP); GROUPWARE; HEALTH CARE; HOTEL . MANAGEMENT; INTERNET TELEPHONE; INVENTORY CONTROL; JOB COSTING; LIBRARY SYSTEMS; LIFE INSURANCE; MAILING LABELS; MATHEMATICAL / STATISTICAL MODELING; ORDER PROCESSING; PAYROLL; PROCESS CONTROL; TAX ACCOUNTING; WEB BROWSER; WORD PROCESSING
    • *
    12.11
  • 12. CUSTOMIZATION
    • MODIFYING SOFTWARE PACKAGE
    • TO MEET ORGANIZATION’S UNIQUE REQUIREMENTS
    • WITHOUT DESTROYING INTEGRITY OF PACKAGE
    • RAISES DEVELOPMENT COSTS
    • *
    12.12
  • 13. EFFECTS OF CUSTOMIZING SOFTWARE ON TOTAL IMPLEMENTATION COSTS 12.13 0 2 4 6 8 10 0.5 1 2 3 4 5 % LINES OF CODE CONVERTED TOTAL IMPLEMENTATION COSTS
  • 14.
    • DESCRIPTION (PRESENT, PROPOSED)
    • RELIABILITY
    • BACKUP
    • SERVICES
    • SYSTEM SPECIFICATIONS
    • CRITERIA
    • DEMONSTRATION (PROTOTYPE)
    • SCHEDULE (BENCH MARKS)
    • PRICE (PENALTIES)
    • SPECIFIC QUESTIONS
    • PROCEDURES FOR RESPONSE
    • *
    REQUEST FOR PROPOSAL (RFP ) Source: Senn, Information Technology in Business (1995) 12.14
  • 15. END-USER DEVELOPMENT
    • END-USERS DEVELOP INFORMATION SYSTEM
    • WITH LITTLE HELP FROM
    • TECHNICAL SPECIALISTS
    • USING 4th GENERATION TOOLS
    • *
    12.15
  • 16. END-USER DEVELOPMENT
    • STRENGTHS:
    • IMPROVED REQUIREMENTS DETERMINATION
    • INCREASED USER INVOLVEMENT & SATISFACTION
    • REDUCED APPLICATION BACKLOG
    • *
    12.16
  • 17. END-USER DEVELOPMENT
    • WEAKNESSES:
    • RELATIVELY INEFFICIENT
    • SLOW TRANSACTION PROCESSING
    • MAY CARRY HIGH COST
    • LARGE FILES CAN DEGRADE PERFORMANCE
    • NONPROCEDURAL APPROACH MAY HAMPER LOGIC & UPDATING REQUIREMENTS
    • *
    12.17
  • 18. MANAGING END-USER DEVELOPMENT
    • INFORMATION CENTER:
    • SPECIAL FACILITY WITHIN ORGANIZATION
    • PROVIDES TRAINING, SUPPORT FOR END-USER-COMPUTING
    • *
    12.18
  • 19. OUTSOURCING
    • CONTRACTING:
    • COMPUTER CENTER OPERATIONS
    • TELECOMMUNICATIONS NETWORKS
    • APPLICATION DEVELOPMENT
    • TO EXTERNAL VENDORS
    • *
    12.19
  • 20. OUTSOURCING
    • WHEN TO OUTSOURCE:
    • IF FIRM WON’T DISTINGUISH ITSELF BY DEVELOPING APPLICATION
    • PREDICTABILITY OF UNINTERRUPTED SERVICE NOT IMPORTANT
    • IF EXISTING SYSTEM IS LIMITED, INEFFECTIVE, INFERIOR
    • *
    12.20
  • 21. SYSTEM BUILDING METHODOLOGIES
    • STRUCTURED METHODOLOGIES
    • OBJECT- ORIENTED SOFTWARE DEVELOPMENT
    • COMPUTER AIDED SOFTWARE ENGINEERING (CASE)
    • SOFTWARE REENGINEERING
    • *
    12.21
  • 22. STRUCTURED METHODOLOGIES
    • TOP DOWN, STEP BY STEP, EACH STEP BUILDS ON PREVIOUS
    • STRUCTURED ANALYSIS
    • STRUCTURED DESIGN
    • STRUCTURED PROGRAMMING
    • FLOWCHARTS
    • *
    12.22
  • 23. STRUCTURED ANALYSIS
    • DEFINES SYSTEM INPUTS, PROCESSES, OUTPUTS
    • PARTITIONS SYSTEM INTO SUBSYSTEMS OR MODULES
    • LOGICAL, GRAPHICAL MODEL OF INFORMATION FLOW
    • DATA FLOW DIAGRAM: Graphical display of component processes, flow of data
    • *
    12.23
  • 24. SYMBOLS FOR DATA FLOW DIAGRAMS (DFD): DATA FLOW PROCESS SOURCE OR SINK FILE 12.24
  • 25. DATA FLOW DIAGRAM: 12.25  GENERATE BILL CUSTOMER GENERATE BALANCE GENERATE REPORT MANAGER PAYMENT FILE CUSTOMER FILE
  • 26. STRUCTURED ANALYSIS
    • DATA DICTIONARY: Controlled definitions of descriptions of all data, such as variable names & types of data
    • PROCESS SPECIFICATIONS: Describes logic of processes at module level
    • *
    12.26
  • 27. STRUCTURED DESIGN
    • DESIGN RULES / TECHNIQUES TO DESIGN SYSTEM, TOP DOWN IN HIERARCHICAL FASHION
    • STRUCTURE CHART
    • STRUCTURED PROGRAMMING
    • MODULE
    • SEQUENCE CONSTRUCT
    • SELECTION CONSTRUCT
    • *
    12.27
  • 28. 12.28 CALCULATE GROSS PAY CALCULATE NET PAY CALCULATE PAY PROCESS PAYROLL UPDATE MASTER FILE GET VALID INPUTS WRITE OUTPUTS GET INPUTS VALIDATE INPUTS WRITE OUTPUTS HIGH LEVEL STRUCTURE CHART: HIGH LEVEL STRUCTURE CHART: (WHITE BOXES ARE MODULES) (WHITE BOXES ARE MODULES )
  • 29. STRUCTURED PROGRAMMING:
    • DISCIPLINE TO ORGANIZE, CODE PROGRAMS
    • SIMPLIFIES CONTROL PATHS
    • EASY TO UNDERSTAND, MODIFY
    • MODULE HAS ONE INPUT, ONE OUTPUT
    • *
    12.29
  • 30. STRUCTURED PROGRAMMING:
    • MODULE: Logical unit of program. performs specific task(s)
    • SEQUENCE CONSTRUCT: Sequential steps or actions in program logic; streamlines flow
    • SELECTION CONSTRUCT: IF Condition R is True THEN Action C ELSE Action D
    • ITERATION CONSTRUCT: WHILE Condition is True DO Action E
    • *
    12.30
  • 31. SYSTEM FLOWCHART SYMBOLS: 12.31
  • 32. SYSTEM FLOWCHART: 12.32 LOAD & VALIDATE COMPARE & UPDATE VALID TRANS- ACTIONS PAYROLL SYSTEM TIME CARDS HUMAN RESOURCES DATA PAYROLL MASTER UPDATED PAYROLL MASTER DIRECT DEPOSITS GENERAL LEDGER PAYROLL REPORTS & CHECKS PAYROLL MASTER
  • 33. PROGRAM FLOWCHART SYMBOLS: 12.33
  • 34. PROGRAM FLOWCHART: 12.34 PROCESS A PROCESS B SEQUENCE PROCESS C PROCESS D R TRUE SELECTION PROCESS E S TRUE ITERATION
  • 35. PROGRAM FLOWCHART: 12.35 1 END REPORT MORE? 2 PRINT 1 2 START READ >$10,000 <$10,000 PROCESS A PROCESS B
  • 36. OBJECT - ORIENTED SOFTWARE DEVELOPMENT
    • DE-EMPHASIZES PROCEDURES
    • SHIFTS FOCUS FROM MODELS & DATA
    • TO OBJECTS , WHICH COMBINE DATA & PROCEDURES
    • OBJECTS REUSABLE
    • SYSTEM: Classes; objects; relationships
    • REDUCES DEVELOPMENT TIME & COST
    • *
    12.36
  • 37. COMPUTER AIDED SOFTWARE ENGINEERING (CASE)
    • AUTOMATION OF SOFTWARE METHODOLOGIES
    • PRODUCES CHARTS; DIAGRAMS; SCREEN & REPORT GENERATORS; DATA DICTIONARIES; PROGRESS REPORTS; ANALYSIS; CHECKING TOOLS; CODE; DOCUMENTATION
    • *
    CASE 12.37
  • 38. COMPUTER AIDED SOFTWARE ENGINEERING (CASE)
    • INCREASES PRODUCTIVITY & QUALITY:
    • ENFORCES DEVELOPMENT DISCIPLINE
    • IMPROVES COMMUNICATION
    • DESIGN REPOSITORY FOR OBJECTS
    • AUTOMATES TEDIOUS TASKS
    • AUTOMATES TESTING & CONTROL
    • REQUIRES ORGANIZATIONAL DISCIPLINE
    • *
    CASE 12.38
  • 39. SOFTWARE REENGINEERING
    • SALVAGES & UPGRADES AGING SOFTWARE
    • DELAYS EXPENSIVE REPLACEMENT
    • REVERSE ENGINEERING: CONVERTING EXISTING PROGRAMS, FILES, DATABASE FOR USE IN NEW APPLICATIONS
    • *
    12.39
  • 40. SOFTWARE REENGINEERING
    • REVISE DESIGN & PROGRAM SPECIFICATIONS
    • FORWARD ENGINEERING: USE REVISED MATERIALS TO GENERATE NEW, STRUCTURED CODE; STRUCTURED & MAINTAINABLE SYSTEM
    • *
    12.40
  • 41. Connect to the INTERNET PRESS LEFT MOUSE BUTTON ON ICON TO CONNECT TO THE LAUDON & LAUDON WEB SITE FOR MORE INFORMATION ON THIS CHAPTER 12.41
  • 42. 12.42 12. APPROACHES TO SYSTEMS-BUILDING

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