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12. APPROACHES TO SYSTEMS-BUILDING. 12.1. LEARNING OBJECTIVES. APPRAISE SYSTEM BUILDING ALTERNATIVES COMPARE STRENGTHS, WEAKNESSES OF APPROACHES ASSESS SOLUTIONS TO PROBLEMS CREATED BY APPROACHES DESCRIBE TOOLS, METHODOLOGIES OF SYSTEMS DEVELOPMENT *. 12.2. MANAGEMENT CHALLENGES.

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12 1

12.

APPROACHES TO

SYSTEMS-BUILDING

12.1


Learning objectives

LEARNING OBJECTIVES

  • APPRAISE SYSTEM BUILDING ALTERNATIVES

  • COMPARE STRENGTHS, WEAKNESSES OF APPROACHES

  • ASSESS SOLUTIONS TO PROBLEMS CREATED BY APPROACHES

  • DESCRIBE TOOLS, METHODOLOGIES OF SYSTEMS DEVELOPMENT

    *

12.2


Management challenges

MANAGEMENT CHALLENGES

  • TRADITIONAL SYSTEMS LIFECYCLE

  • ALTERNATIVE SYSTEM-BUILDING APPROACHES

  • SYSTEM-BUILDING METHODOLOGIES & TOOLS

    *

12.3


System lifecycle

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


System lifecycle1

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


System lifecycle2

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


Alternative system building approaches

ALTERNATIVE SYSTEM-BUILDING APPROACHES

  • PROTOTYPING

  • APPLICATION SOFTWARE PACKAGES

  • END-USER DEVELOPMENT

  • OUTSOURCING

    *

12.7


Prototyping

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


Steps in prototyping

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


Application software packages

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


Selected examples of application programs

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


Customization

CUSTOMIZATION

MODIFYING SOFTWARE PACKAGE

TO MEET ORGANIZATION’S UNIQUE REQUIREMENTS

WITHOUT DESTROYING INTEGRITY OF PACKAGE

RAISES DEVELOPMENT COSTS

*

12.12


Effects of customizing software on total implementation costs

10

8

6

4

COSTS

TOTAL IMPLEMENTATION

2

0

0.5

1

2

3

4

5

% LINES OF CODE CONVERTED

EFFECTS OF CUSTOMIZING SOFTWARE ON TOTAL IMPLEMENTATION COSTS

12.13


12 1

REQUEST FOR PROPOSAL (RFP)

  • DESCRIPTION (PRESENT, PROPOSED)

  • RELIABILITY

  • BACKUP

  • SERVICES

  • SYSTEM SPECIFICATIONS

  • CRITERIA

  • DEMONSTRATION (PROTOTYPE)

  • SCHEDULE (BENCH MARKS)

  • PRICE (PENALTIES)

  • SPECIFIC QUESTIONS

  • PROCEDURES FOR RESPONSE

    *

12.14

Source: Senn, Information Technology in Business (1995)


End user development

END-USER DEVELOPMENT

END-USERS DEVELOP INFORMATION SYSTEM

WITH LITTLE HELP FROM

TECHNICAL SPECIALISTS

USING 4th GENERATION TOOLS

*

12.15


End user development1

END-USER DEVELOPMENT

STRENGTHS:

  • IMPROVED REQUIREMENTS DETERMINATION

  • INCREASED USER INVOLVEMENT & SATISFACTION

  • REDUCED APPLICATION BACKLOG

    *

12.16


End user development2

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


Managing end user development

MANAGING END-USER DEVELOPMENT

INFORMATION CENTER:

  • SPECIAL FACILITY WITHIN ORGANIZATION

  • PROVIDES TRAINING, SUPPORT FOR END-USER-COMPUTING

    *

12.18


Outsourcing

OUTSOURCING

CONTRACTING:

  • COMPUTER CENTER OPERATIONS

  • TELECOMMUNICATIONS NETWORKS

  • APPLICATION DEVELOPMENT

    TO EXTERNAL VENDORS

    *

12.19


Outsourcing1

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


System building methodologies

SYSTEM BUILDING METHODOLOGIES

  • STRUCTURED METHODOLOGIES

  • OBJECT- ORIENTED SOFTWARE DEVELOPMENT

  • COMPUTER AIDED SOFTWARE ENGINEERING (CASE)

  • SOFTWARE REENGINEERING

    *

12.21


Structured methodologies

STRUCTURED METHODOLOGIES

TOP DOWN, STEP BY STEP, EACH STEP BUILDS ON PREVIOUS

  • STRUCTURED ANALYSIS

  • STRUCTURED DESIGN

  • STRUCTURED PROGRAMMING

  • FLOWCHARTS

    *

12.22


Structured analysis

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


Structured analysis1

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


Structured design

STRUCTURED DESIGN

DESIGN RULES / TECHNIQUES TO DESIGN SYSTEM, TOP DOWN IN HIERARCHICAL FASHION

  • STRUCTURE CHART

  • STRUCTURED PROGRAMMING

  • MODULE

  • SEQUENCE CONSTRUCT

  • SELECTION CONSTRUCT

    *

12.27


Structured programming

STRUCTURED PROGRAMMING:

  • DISCIPLINE TO ORGANIZE, CODE PROGRAMS

  • SIMPLIFIES CONTROL PATHS

  • EASY TO UNDERSTAND, MODIFY

  • MODULE HAS ONE INPUT, ONE OUTPUT

    *

12.29


Structured programming1

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


Object oriented software development

OBJECT - ORIENTED SOFTWARE DEVELOPMENT

  • DE-EMPHASIZES PROCEDURES

  • SHIFTS FOCUS FROM MODELS & DATA

  • TOOBJECTS, WHICH COMBINE DATA & PROCEDURES

  • OBJECTS REUSABLE

  • SYSTEM: Classes; objects; relationships

    REDUCES DEVELOPMENT TIME & COST

    *

12.36


Computer aided software engineering case

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


Computer aided software engineering case1

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


Software reengineering

SOFTWARE REENGINEERING

  • SALVAGES & UPGRADES AGING SOFTWARE

  • DELAYS EXPENSIVE REPLACEMENT

  • REVERSE ENGINEERING:CONVERTING EXISTING PROGRAMS, FILES, DATABASE FOR USE IN NEW APPLICATIONS

    *

12.39


Software reengineering1

SOFTWARE REENGINEERING

  • REVISE DESIGN & PROGRAM SPECIFICATIONS

  • FORWARD ENGINEERING:USE REVISED MATERIALS TO GENERATE NEW, STRUCTURED CODE; STRUCTURED & MAINTAINABLE SYSTEM

    *

12.40


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