chap07.ppt 273KB May 20 2010 09:29:46 PM

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Chapter 7

System Life Cycle

Methodologies

MANAGEMENT INFORMATION SYSTEMS 8/E Raymond McLeod, Jr. and George Schell

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The Systems Life Cycle

(SLC)

 MethodologyMethodology

– Recommended way of doing something_{Recommended way of doing something}

 An application of the systems approach An application of the systems approach

to the task of developing and using a

computer-based system

 Often called waterfall approachOften called waterfall approach

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Phases in the SDLC

1) Planning

2) Analysis

3) Design

4) Implementation

5) Use

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The System Development

Life Cycle (SDLC)

 SDLC is the phrase that encompasses the planning, SDLC is the phrase that encompasses the planning,

analysis, design, and implementation phases of the system analysis, design, and implementation phases of the system

life cycle life cycle

 Who participatesWho participates

– IS personnel_{IS personnel} – User_User

– Information specialists can consult_{Information specialists can consult}

 TraditionalTraditional

– _{Information specialists working with users.}_{Information specialists working with users.} – A new strategy: Outsourcing_{A new strategy: Outsourcing}

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Life Cycle Management

 An upward migrationAn upward migration

 Executive responsibilityExecutive responsibility  MIS steering committeeMIS steering committee

– _Functions_Functions

» Set policy_{Set policy}

» Control the purse strings_{Control the purse strings} » _{Resolve conflicts}_{Resolve conflicts}

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Executives MIS Steering

Committee Project leader -Warehouse location model team

Project leader MRP 11 team

Project leader ISDN

system team

Project leader

HRIS team

Marketing

Manufacturing

Finance

Human Resources

Project leader Credit approval system team

Managers of Systems Life Cycles are Arranged in a Hierarchy

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Main Advantages of

the Steering Committee

 Total firm supportTotal firm support

 Projects will be characterized by good Projects will be characterized by good

planning and control

 Establishes policies, provides fiscal control, Establishes policies, provides fiscal control,

and resolves conflicts

Since the steering committee will probably not get involved with the details of the work, a project team is usually appointed.

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Planning Phase

 BenefitsBenefits

– _{Define scope of the project}_{Define scope of the project}

– _{Spot potential problems}_{Spot potential problems}

– _{Arrange tasks in sequence}_{Arrange tasks in sequence}

– _{Provide basis for control}_{Provide basis for control}

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Steps

1. Recognize problem (the trigger)

2. Define problem

3. Set objectives

4. Identify constraints

Recall that objectives, standards, and constraints are problem-solving elements.

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Steps (cont.)

5.Conduct feasibility study (TENLOS)Conduct feasibility study (TENLOS)

– T_Technicalechnical

– E_Economic returnconomic return

– _N_N_{oneconomic return}_{oneconomic return} – L_Legal and ethicalegal and ethical

– O_Operationalperational

– S_Schedulechedule

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Steps (cont.)

6.Prepare study project proposalPrepare study project proposal

– Goes to MIS steering committee_{Goes to MIS steering committee}

7.Approve or disapprove (go/no go)Approve or disapprove (go/no go)

– _{Key questions?}_{Key questions?}

1.Will the system accomplish its goals?Will the system accomplish its goals? 2.

2.Is this the best way to go about it?Is this the best way to go about it?

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Steps (cont.)

8.Establish a control mechanismEstablish a control mechanism

– Think in terms of:_{Think in terms of:}

» 1. What_{1. What} » _{2. Who}_{2. Who}

» 3. When (Person-months versus calendar months)_{3. When (Person-months versus calendar months)}

– PERT and CPM network diagrams_{PERT and CPM network diagrams}

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Define the problem

Consult Consult

Prepare a system study proposal

Establish a control mechanism

Approve or disapprove the study project

Recognize the problem Set system objectives Identify system constraints

The Planning Phase

MIS Steering Comm Manager Systems Analyst MIS Steering Comm Manager Systems Analyst

1. 1. 2. 2. 3. 3. 4. 4. 5. 6. 7. 7. 8. 8. Conduct a feasibility study 7-13

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Outline of a System Study Proposal

1. Executive summary 2. Introduction

3. System objectives and constraints 4. Possible system alternatives

5. The recommended system study project 5.1 Tasks to be performed

5.2 Human resource requirements 5.3 Schedule of work

5.4 Estimated cost

6. Expected impact of the system

6.1 Impact on the firm’s organization structure 6.2 Impact on the firm’s operations

6.3 Impact on the firms resources

7. General development plan (analysis, design, and implementation phase)

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A Project Schedule

Functional System:

Functional System: MarketingMarketing Subsystem:

Subsystem: ProductProduct Model:

Model: Product DeletionProduct Deletion

Subtask

Subtask _Estimate_EstimateTime Time

(Person Months) (Person Months) Responsibility Responsibility 1. Identify 1. Identify deletion criteria deletion criteria

2. Identify output

information information requirements requirements Systems analyst Systems analyst Product manager Product manager Systems analyst Systems analyst Network specialist Network specialist Product manager Product manager 0.75 0.75 0.25 0.25 7-15

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Project Schedule (cont.)

3. Identify input data Systems analyst 0.50 3. Identify input data Systems analyst 0.50

requirements DBArequirements DBA

4. Prepare new system Systems analyst 2.00 4. Prepare new system Systems analyst 2.00

documentation documentation

5. Design network Network specialist 1.50 5. Design network Network specialist 1.50 6. Design database DBA 0.50 6. Design database DBA 0.50 7. Review design Product manager 0.25 7. Review design Product manager 0.25

Systems analystSystems analyst

8. Prepare program Programmer 1.00 8. Prepare program Programmer 1.00

documentationdocumentation

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Project Schedule (cont.)

9. Code program Programmer 1.25 9. Code program Programmer 1.25 10. Test program Programmer 0.75 10. Test program Programmer 0.75

Operations staffOperations staff

11. Approve program Product manager 0.50 11. Approve program Product manager 0.50

VP of marketingVP of marketing

12. Prepare database DBA 2.00 12. Prepare database DBA 2.00 13. Educate users Systems analyst 0.50 13. Educate users Systems analyst 0.50 14. Cutover to model Operations staff 0.75 14. Cutover to model Operations staff 0.75

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Analysis Phase

 StepsSteps

1.AnnounceAnnounce

» Reasons for project_{Reasons for project}

» _{Purpose: inform and counteract fear}_{Purpose: inform and counteract fear}

2.Organize project team Organize project team

» User(s)_User(s) » Specialists_Specialists » _{Define roles}_{Define roles}

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Analysis Phase (cont.)

3. Define information needsDefine information needs

» Methods_Methods

 Personal interview (the preferred method)Personal interview (the preferred method)  ObservationObservation

 Record search (includes review of existing Record search (includes review of existing

documentation) documentation)

 SurveysSurveys

A project directory can be

maintained as an encompassing set of documentation to describe the

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Analysis Phase (cont.)

4. Define system performance criteriaDefine system performance criteria 5.

5. Prepare design proposalPrepare design proposal

(Compare to system study proposal)

6. Approve or disapprove the design _{Approve or disapprove the design}

project

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Announce the system study

Organize the project team Define information needs

Define system performance criteria

Prepare design proposal Approve or disapprove the design project

2. 3. 4.

The Analysis Phase The Analysis Phase

MIS Steering MIS Steering

Committee

Committee ManagerManager Systems AnalystSystems Analyst

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Outline of a Design Proposal

1. Executive summary 2. Introduction

3. Problem definition

4. System objectives and constraints 5. Performance criteria

6. Possible system alternatives

7. The recommended design project 7.1 Tasks to be performed

7.2 Human resource requirements 7.3 Schedule of work

7.4 Estimated cost

8. Expected impact of the system

8.1 Impact on the firm’s organization structure 8.2 Impact on the firm’s operations

8.3 Impact on the firms resources

9. General development plan (analysis, design, and implementation) 10. Summary

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Approve or disapprove the system

implementation implementation Prepare the Prepare the detailed detailed design design system system Identify Identify alternate alternate system system configurations configurations Evaluate Evaluate system system configurations configurations Select the Select the best best configuration configuration Prepare the Prepare the implementation implementation proposal proposal 1. 1. 2. 2. 3. 3. 4. 4. 5. 5. 6.

MIS Steering Committee

MIS Steering Committee ManagerManager Systems AnalystSystems Analyst

The Design Phase

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Design Phase

1.Prepare detailed designPrepare detailed design

– Structured design (top down)_{Structured design (top down)}

» System level_{System level} » _{Subsystem level}_{Subsystem level}

– _{Documentation tools}_{Documentation tools}

2. Identify alternate system configurations

– _{Refine to a manageable set}_{Refine to a manageable set}

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Data Flow Diagram of Order Entry System

Sales order edit rejects Order log Sales order credit rejects Customer credit file Customer 1.1.1 Edit order data 1.1.2 Compute credit check 1.1.3 Log in orders 1.1.4 Mark filled orders 1.2 1.3

Sales orders Edit rejects

Rejected sales order notices

Edited orders

Credit data Edited and checked orders

Credit rejects Accepted

orders

Completed orders Date filled Order data

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Hardware Choices Make Possible Hardware Choices Make Possible

Multiple System Configurations Multiple System Configurations

System Elements

System Elements AlternativesAlternatives

•CRT terminalCRT terminal

•Hardcopy terminalHardcopy terminal

•OCROCR Input

Order log

Customer credit file Rejected orders file Accepted orders file Completed orders file Rejected orders notice Processing