SYSTEM DEVELOPMENT METHODS

노형종 , 문정곤 , 허승구

Class Term Project2005 Spring

POSTECH

IE 381 Management Information Systems

Contents

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Systems Development Life Cycle (SDLC)

Rapid Application Development (RAD)

Prototyping

Definition The overall process of developing information systems through a

multi step process from investigation of initial requirements through analysis, design, implementation and maintenance.

<Russell Kay, Computer World>

Types of SDLC Waterfall, Fountain, Spiral

Outputs from one step inputs to next Often referred to as the “waterfall” model

(the oldest one - early 1970s)

Systems Development Life Cycle

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Waterfall Development Method

Systems AnalysisSystems Designs

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Phase 1: Investigation Initialization

Management planning, Users’ needs & opportunities

Formal definition Objective, motivation, scope, boundaries, constraints, strategy Verifying a problem or deficiency really exists, or to pass judgment on the new

requirement.

Feasibilities studies Technical Feasibility is the availability of computing hardware and software to

do a particular job. In many cases the managers’ concerns were well founded because the technology did not exist.

Economic Feasibility is the ability of a system to pay for itself in monetary terms. Management does not want to spend a dollar unless it receives more than a dollar in return. Ex) The cost-benefit Analysis, Break-even Analysis, Payback Analysis, NPV.

Operational Feasibility relates to the ability of the people working within a system to do their jobs in a prescribed manner. Ex) Ability of Users and Participants & Attitudes of Users and Participants

Organizational Feasibility. How well a proposed e-commerce system firs the company’s plans for developing Web-based sales, marketing, and financial system.

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Analysis What a system should do to meet the needs of users.

Determine requirementsStudy current systemStructure requirements and eliminate redundancies

Requirement AnalysisFunctional requirementsPerformance requirements

Generate alternative designs Compare alternatives Recommend best alternative

Phase 2: Analysis

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Design How the system will accomplish this objective.

User interface DesignScreen, Form, Report, and Dialog

Design

Data DesignData Element structure Design

Process DesignProgram and Procedure Design

Phase 3: Design

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Evaluating Hardware, Software, and Services Companies may use a scoring system of evaluation when

there are several competing proposals for a hardware or software acquisition.

Software Development or Modification Documentation

Major mechanism of communication during development process

Data Conversion Correcting incorrect data, filtering our unwanted data,

consolidating data form several data warehouses. Testing

Testing & Debugging the Software Training

Phase 4: Implementation

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Phase 4: Implementation

Conversion

Parallel Strategy

Plunge Strategy

Phased Strategy

Pilot Strategy

Run old & new systems for awhile to check validity. Safe.

Install in one part of organization at a time. Learn and adapt

In large system change one function at a time (e.g., order entry)

Start using entire system. Can be dangerous if errors exist.

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Modification Modifying established system due to changes

in the system for potential problems or necessary change.

Correcting errors

Feedback

Phase 5: Maintenance

<Martin, “Managing Information Technology” p.395>

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SDLC Pros and Cons

Advantages: Highly structured, systematic process Thorough requirements definition Clear milestone with business management

sign-offs Disadvantages:

Does not account well for evolving requirements during project

Time-consuming (and costly) process

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Motivation of RAD

Limitation of SDLC Pressures for businesses to speed up Shorter development lifecycles Competition in changing global environment

“Why wait 3 years to develop systems likely to be obsolete upon completion?”

RAD methodology was born!

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Definition of RAD

Rapid Application Design A system development methodology

created to radically decrease the time needed to design and implement information systems

<James Martin, “RAD, CIRCA”>

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The 4 Essentials of RAD (1/2)

Management Executives. Support for the RAD

People Participation in JAD type Specialized team for RAD: SWAT

“Skilled With Advanced Tools”

Joint application design (JAD) - Group Decision Support System- Users, Managers and Analysts work together for several days- System requirements are reviewed- Structured meetings

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The 4 Essentials of RAD (2/2)

Methodologies RAD life cycle: Users play key roles

Tools Fourth-generation languages and CASE tools

that facilitate prototyping and code generation

Computer-Aided Software Engineering (CASE) – Any software tool to transfer some of the systems development workload from the human developer to the computer by automating one or more steps of a software development methodology

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RAD Life Cycle

Executives, managers, users determine requirements JRP workshops to agree requirements, overall planning

JAD session to develop basis designCASE tool is used

Generate codeEnd users validate design

Delivery of new system to users

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Definition of Prototyping

The overall process of developing IS, which enables creation of system (or part of system) more quickly, then revising after users have tried it

< Martin, “Managing Information Technology” >

Selected features : only some essential features included in prototype, more added later

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Prototyping Examples

Graphic user interface: usually needs several modification to meet the user requirements

A completely operational prototype can be used as a pilot

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Install in one part of organization at a time. Learn and adapt

Pilot Strategy

Prototyping is similar to decide what shall you be dressed in. This girl is the user. Various designs of dresses are the prototypes. If the user does not like the proposed one, developers do modification until it meets the user’s requirements.

Prototyping Life Cycle

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Prototype cycle

Prototyping Pros & Cons

Advantages: Communications between the developer and user are

improved The user plays a more active role in system development The information specialists and the user spend less time and

effort in developing the system Implementation is much easier because the user knows

what to expect

Disadvantages: End prototype often lacks security and control features

May not undergo as rigorous testing

Final documentation may be less complete

More difficult to manage user expectations

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Prototyping

RAD

SDLC

SPEED

STABILITY

3 Types of System Development

Large and complex system

Hybrid type of SDLC and Prototyping

When requirements are hard to define

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References

O’Brien, James, “Introduction to Information Systems”, McGraw-Hill

Martin, James, “Managing Information Technology” ,Prentice Hall

Martin, James, “RAD, circa - Cooperative Intelligent Real-Time Control Architecture”,1991

Kenneth, at al, “Management Information Systems”, Prentice hall

Raymond, at al, “Management Information Systems”, Prentice hall

Russell, Kay, “Quickstudy”, http://www.computerworld.com

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“MIS is one of the most appreciated course by the graduates”

Special Thanks To

POSMIS

Questions?

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