11. approaches to system building 11.1. system lifecycle project definition: is there a problem? can...

11. APPROACHES TO SYSTEM BUILDING

11. APPROACHES TO SYSTEM BUILDING

DATA FLOW DIAGRAMDATA FLOW DIAGRAM

GENERATE BILL

CUSTOMER

GENERATE BALANCE

GENERATE REPORT

MANAGER

PAYMENTFILE

CUSTOMERFILE

11.1

SYSTEM LIFECYCLESYSTEM LIFECYCLE

• PROJECT DEFINITION: Is There a PROJECT DEFINITION: Is There a Problem? Can it be Solved with a Project?Problem? Can it be Solved with a Project?

• SYSTEM STUDY: Analyze problems in SYSTEM STUDY: Analyze problems in Existing Systems; Define Objectives Existing Systems; Define Objectives Evaluate AlternativesEvaluate Alternatives

• DESIGN: Logical & Physical Specifications DESIGN: Logical & Physical Specifications for Systems Solutionfor Systems Solution

• PROGRAMMING: Develop Software CodePROGRAMMING: Develop Software Code

**11.2


• INSTALLATION: Construct, Test, Train, INSTALLATION: Construct, Test, Train, Convert to New SystemConvert to New System

• POSTINSTALLATION: On-going POSTINSTALLATION: On-going Evaluation, Modifications for Improvement Evaluation, Modifications for Improvement to meet New Requirementsto meet New Requirements

NECESSARY FOR LARGE, COMPLEX NECESSARY FOR LARGE, COMPLEX SYSTEMS & PROJECTSSYSTEMS & PROJECTS

**


11.3


• CAN BE COSTLY, TIME CONSUMINGCAN BE COSTLY, TIME CONSUMING• MAY ENCOURAGE FREEZING MAY ENCOURAGE FREEZING

SPECIFICATIONS EARLY IN SPECIFICATIONS EARLY IN DEVELOPMENTDEVELOPMENT

• MAY NOT BE SUITABLE FOR SMALL, MAY NOT BE SUITABLE FOR SMALL, LESS STRUCTURED SYSTEMSLESS STRUCTURED SYSTEMS

**


11.4

PROTOTYPINGPROTOTYPING

PROCESS OF BUILDING EXPERIMENTAL PROCESS OF BUILDING EXPERIMENTAL SYSTEM TO DEMONSTRATE, EVALUATE SYSTEM TO DEMONSTRATE, EVALUATE

APPROACH; USERS REFINE NEEDSAPPROACH; USERS REFINE NEEDS

• PROTOTYPE: Preliminary working PROTOTYPE: Preliminary working version of Information System for version of Information System for Demonstration, Evaluation PurposesDemonstration, Evaluation Purposes

• ITERATIVE PROCESSITERATIVE PROCESS

**

11.5

STEPS IN PROTOTYPINGSTEPS IN PROTOTYPING

• IDENTIFY USER’S REQUIREMENTSIDENTIFY USER’S REQUIREMENTS

• DEVELOP PROTOTYPEDEVELOP PROTOTYPE

• USE PROTOTYPEUSE PROTOTYPE

• REVISE & ENHANCE PROTOTYPEREVISE & ENHANCE PROTOTYPE

BEST FOR DESIGN OF END-USER BEST FOR DESIGN OF END-USER INTERFACE: How End-user Interacts INTERFACE: How End-user Interacts With SystemWith System

**11.6

APPLICATION SOFTWARE PACKAGES

APPLICATION SOFTWARE PACKAGES

PREWRITTEN, PRECODED APPLICATION PREWRITTEN, PRECODED APPLICATION SOFTWARE, COMMERCIALLY SOFTWARE, COMMERCIALLY AVAILABLE FOR SALE OR LEASEAVAILABLE FOR SALE OR LEASE

• GEARED TO COMMON REQUIREMENTSGEARED TO COMMON REQUIREMENTS• CUSTOMIZATION: Modification of CUSTOMIZATION: Modification of

Software to Meet Organization’s NeedsSoftware to Meet Organization’s Needs• MUST WEIGH COSTS / BENEFITSMUST WEIGH COSTS / BENEFITS

**

11.7

CUSTOMIZATIONCUSTOMIZATION

MODIFYING SOFTWARE PACKAGE MODIFYING SOFTWARE PACKAGE

TO MEET ORGANIZATION’S UNIQUE TO MEET ORGANIZATION’S UNIQUE REQUIREMENTSREQUIREMENTS

WITHOUT DESTROYING INTEGRITYWITHOUT DESTROYING INTEGRITY

OF PACKAGEOF PACKAGE

RAISES DEVELOPMENT COSTSRAISES DEVELOPMENT COSTS

**

11.8

EFFECTS OF CUSTOMIZING SOFTWARE ON TOTAL IMPLEMENTATION COSTS

EFFECTS OF CUSTOMIZING SOFTWARE ON TOTAL IMPLEMENTATION COSTS

0

2

4

6

8

10

0.5 1 2 3 4 5

% LINES OF CODE CONVERTED% LINES OF CODE CONVERTED

TO

TA

L IM

PL

EM

EN

TA

TIO

N

TO

TA

L IM

PL

EM

EN

TA

TIO

N

CO

ST

SC

OS

TS

11.9

END-USER DEVELOPMENTEND-USER DEVELOPMENT

END-USERS DEVELOP INFORMATION END-USERS DEVELOP INFORMATION SYSTEMSYSTEM

WITH LITTLE HELP FROM WITH LITTLE HELP FROM

TECHNICAL SPECIALISTSTECHNICAL SPECIALISTS

USING 4th GENERATION TOOLSUSING 4th GENERATION TOOLS

**

11.10


STRENGTHS:STRENGTHS:• INCREASED PRODUCTIVITY USING 4th INCREASED PRODUCTIVITY USING 4th

GENERATION TOOLSGENERATION TOOLS• QUERY LANGUAGESQUERY LANGUAGES• GRAPHICSGRAPHICS• REPORT GENERATORSREPORT GENERATORS• APPLICATION GENERATORSAPPLICATION GENERATORS• SHORT DEVELOPMENT TIMESSHORT DEVELOPMENT TIMES

**

11.11


WEAKNESSES:WEAKNESSES:• RELATIVELY INEFFICIENTRELATIVELY INEFFICIENT• SLOW TRANSACTION PROCESSINGSLOW TRANSACTION PROCESSING• MAY CARRY HIGH COSTMAY CARRY HIGH COST• LARGE FILES CAN DEGRADE PERFORMANCELARGE FILES CAN DEGRADE PERFORMANCE• NONPROCEDURAL APPROACH MAY HAMPER NONPROCEDURAL APPROACH MAY HAMPER

LOGIC & UPDATING REQUIREMENTSLOGIC & UPDATING REQUIREMENTS

**

11.12


MANAGEMENT BENEFITS:MANAGEMENT BENEFITS:• IMPROVED REQUIREMENTS IMPROVED REQUIREMENTS

DETERMINATIONDETERMINATION• INCREASED USER INVOLVEMENT & INCREASED USER INVOLVEMENT &

SATISFACTIONSATISFACTION• REDUCED APPLICATION BACKLOGREDUCED APPLICATION BACKLOG

**

11.13


MANAGEMENT PROBLEMS:MANAGEMENT PROBLEMS:• MEET ORGANIZATIONAL OBJECTIVES?MEET ORGANIZATIONAL OBJECTIVES?• QUALITY ASSURANCE?QUALITY ASSURANCE?• INADEQUATE METHODOLOGY; TESTING; INADEQUATE METHODOLOGY; TESTING;

DOCUMENTATION?DOCUMENTATION?• LOST CONTROL OVER DATA?LOST CONTROL OVER DATA?

**

11.14


INFORMATION CENTER:INFORMATION CENTER:• SPECIAL FACILITY WITHIN SPECIAL FACILITY WITHIN

ORGANIZATIONORGANIZATION• PROVIDES TRAINING, SUPPORT FORPROVIDES TRAINING, SUPPORT FOR• END-USER-COMPUTINGEND-USER-COMPUTING

**

11.15

OUTSOURCINGOUTSOURCING

CONTRACTING:CONTRACTING:• COMPUTER CENTER OPERATIONSCOMPUTER CENTER OPERATIONS• TELECOMMUNICATIONS NETWORKSTELECOMMUNICATIONS NETWORKS• APPLICATION DEVELOPMENTAPPLICATION DEVELOPMENT

TO EXTERNAL VENDORSTO EXTERNAL VENDORS

**

11.16

REWARDS & PENALTIES OF OUTSOURCINGREWARDS & PENALTIES OF OUTSOURCING

REWARDS FOR EXCELLENCEREWARDS FOR EXCELLENCE

PE

NA

LT

Y F

OR

PR

OB

LE

MS

PE

NA

LT

Y F

OR

PR

OB

LE

MS

LOWLOW HIGHHIGH

HIGHHIGH

HIGH HIGH OUTSOURCING OUTSOURCING POTENTIALPOTENTIAL

CAFETERIA CAFETERIA ACCOUNTINGACCOUNTING

PAYROLLPAYROLL PLANT PLANT SCHEDULINGSCHEDULING

ENGINEERING ENGINEERING ANALYSIS TOOLSANALYSIS TOOLS

AIRLINE AIRLINE RESERVATIONSRESERVATIONS

11.17

SYSTEM BUILDING METHODOLOGIESSYSTEM BUILDING METHODOLOGIES

• STRUCTURED METHODOLOGIESSTRUCTURED METHODOLOGIES

• OBJECT- ORIENTED SOFTWARE OBJECT- ORIENTED SOFTWARE DEVELOPMENTDEVELOPMENT

• COMPUTER AIDED SOFTWARE COMPUTER AIDED SOFTWARE ENGINEERING (CASE)ENGINEERING (CASE)

• SOFTWARE REENGINEERINGSOFTWARE REENGINEERING

**

11.18

STRUCTURED METHODOLOGIESSTRUCTURED METHODOLOGIES

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

• STRUCTURED ANALYSISSTRUCTURED ANALYSIS

• STRUCTURED DESIGNSTRUCTURED DESIGN

• STRUCTURED PROGRAMMINGSTRUCTURED PROGRAMMING

• FLOWCHARTSFLOWCHARTS

**

11.19

STRUCTURED ANALYSISSTRUCTURED ANALYSIS

• DEFINES SYSTEM INPUTS, PROCESSES, DEFINES SYSTEM INPUTS, PROCESSES, OUTPUTSOUTPUTS

• PARTITIONS SYSTEM INTO SUBSYSTEMS PARTITIONS SYSTEM INTO SUBSYSTEMS OR MODULESOR MODULES

• LOGICAL, GRAPHICAL MODEL OF LOGICAL, GRAPHICAL MODEL OF INFORMATION FLOWINFORMATION FLOW

• DATA FLOW DIAGRAM: Graphical Display DATA FLOW DIAGRAM: Graphical Display of Component Processes, Flow of Dataof Component Processes, Flow of Data

**11.20

DATA FLOW DIAGRAMDATA FLOW DIAGRAM

GENERATE BILL

CUSTOMER

GENERATE BALANCE

GENERATE REPORT

MANAGER

PAYMENTFILE

CUSTOMERFILE

11.21

STRUCTURED ANALYSISSTRUCTURED ANALYSIS

• DATA DICTIONARY: Controlled Definitions DATA DICTIONARY: Controlled Definitions of Descriptions of all Data, such as of Descriptions of all Data, such as Variable Names & Types of DataVariable Names & Types of Data

• PROCESS SPECIFICATIONS: Describes PROCESS SPECIFICATIONS: Describes Logic of Processes at Module Level Logic of Processes at Module Level

**

11.22

STRUCTURED DESIGNSTRUCTURED DESIGN

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

• STRUCTURE CHARTSTRUCTURE CHART• STRUCTURED PROGRAMMINGSTRUCTURED PROGRAMMING• MODULEMODULE• SEQUENCE CONSTRUCTSEQUENCE CONSTRUCT• SELECTION CONSTRUCTSELECTION CONSTRUCT

**11.23

CALCULATE

GROSS PAY

CALCULATE

NET PAY

CALCULATE

PAY

PROCESS

PAYROLL

UPDATE

MASTER FILE

GET VALID

INPUTS

WRITE

OUTPUTS

GET

INPUTS

VALIDATE

INPUTS

WRITE

OUTPUTS

STRUCTURE CHARTSTRUCTURE CHART

(WHITE BOXES ARE MODULES)(WHITE BOXES ARE MODULES)11.24

STRUCTURED PROGRAMMINGSTRUCTURED PROGRAMMING

• DISCIPLINE TO ORGANIZE, CODE DISCIPLINE TO ORGANIZE, CODE PROGRAMSPROGRAMS

• SIMPLIFIES CONTROL PATHSSIMPLIFIES CONTROL PATHS

• EASY TO UNDERSTAND, MODIFYEASY TO UNDERSTAND, MODIFY

• MODULE HAS ONE INPUT, ONE MODULE HAS ONE INPUT, ONE OUTPUTOUTPUT

**

11.25

SYSTEM FLOWCHARTSYSTEM FLOWCHART

1

1

2

2

START

END

READ

PRINT

REPORT

MORE?

>$10,000

<$10,000

PROCESS A

PROCESS B

11.26

OBJECT - ORIENTED SOFTWARE DEVELOPMENT

OBJECT - ORIENTED SOFTWARE DEVELOPMENT

• DEEMPHASIZES PROCEDURESDEEMPHASIZES PROCEDURES• SHIFTS FOCUS FROM MODELS & DATASHIFTS FOCUS FROM MODELS & DATA• TO TO OBJECTSOBJECTS, WHICH COMBINE DATA & , WHICH COMBINE DATA &

PROCEDURESPROCEDURES• OBJECTS REUSABLEOBJECTS REUSABLE• SYSTEM: Classes; Objects; RelationshipsSYSTEM: Classes; Objects; Relationships• REDUCES DEVELOPMENT TIME & COST REDUCES DEVELOPMENT TIME & COST

**

11.27

COMPUTER AIDED SOFTWARE ENGINEERING (CASE)


• AUTOMATION OF SOFTWARE AUTOMATION OF SOFTWARE METHODOLOGIESMETHODOLOGIES

• PRODUCES CHARTS; DIAGRAMS; PRODUCES CHARTS; DIAGRAMS; SCREEN & REPORT GENERATORS; SCREEN & REPORT GENERATORS; DATA DICTIONARIES; PROGRESS DATA DICTIONARIES; PROGRESS REPORTS; ANALYSIS; CHECKING REPORTS; ANALYSIS; CHECKING TOOLS; CODE; DOCUMENTATIONTOOLS; CODE; DOCUMENTATION

**

CASCASEE

11.28

CASCASEE



INCREASES PRODUCTIVITY & QUALITY:INCREASES PRODUCTIVITY & QUALITY:• ENFORCES DEVELOPMENT DISCIPLINEENFORCES DEVELOPMENT DISCIPLINE• IMPROVES COMMUNICATIONIMPROVES COMMUNICATION• DESIGN REPOSITORY FOR OBJECTSDESIGN REPOSITORY FOR OBJECTS• AUTOMATES TEDIOUS TASKSAUTOMATES TEDIOUS TASKS• AUTOMATES TESTING & CONTROLAUTOMATES TESTING & CONTROL• REQUIRES ORGANIZATIONAL DISCIPLINEREQUIRES ORGANIZATIONAL DISCIPLINE

**

11.29

SOFTWARE REENGINEERINGSOFTWARE REENGINEERING

• SALVAGES & UPGRADES AGING SALVAGES & UPGRADES AGING SOFTWARESOFTWARE

• DELAYS EXPENSIVE REPLACEMENTDELAYS EXPENSIVE REPLACEMENT• REVERSE ENGINEERING: CONVERTING REVERSE ENGINEERING: CONVERTING

EXISTING PROGRAMS, FILES, DATABASE EXISTING PROGRAMS, FILES, DATABASE FOR USE IN NEW APPLICATIONSFOR USE IN NEW APPLICATIONS

**

11.30

SOFTWARE REENGINEERINGSOFTWARE REENGINEERING

• REVISE DESIGN & PROGRAM REVISE DESIGN & PROGRAM SPECIFICATIONSSPECIFICATIONS

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

**

11.31

MANAGEMENT CHALLENGESMANAGEMENT CHALLENGES

• DETERMINE RIGHT DEVELOPMENT DETERMINE RIGHT DEVELOPMENT STRATEGYSTRATEGY

• CONTROL ORGANIZATIONAL CONTROL ORGANIZATIONAL SYSTEMS DEVELOPMENTSYSTEMS DEVELOPMENT

• ENFORCING STANDARD ENFORCING STANDARD METHODOLOGYMETHODOLOGY

**

11.32

11. approaches to system building 11.1. system lifecycle project definition: is there a problem? can...

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