Transcript System Devlopment Methods
IE 381 Management Information Systems S
YSTEM
D
EVELOPMENT
M
ETHODS
노형종, 문정곤, 허승구 Class Term Project 2005 Spring POSTECH
Contents
Systems Development Life Cycle (SDLC) Rapid Application Development (RAD) Prototyping 1/21
Systems Development Life Cycle
Definition The overall process of developing information systems through a multi step process from investigation of initial requirements through analysis, design, implementation and maintenance.
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waterfall
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model (the oldest one - early 1970s) 2/21
Waterfall Development Method
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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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Phase 2: Analysis
Analysis What a system should do to meet the needs of users.
Determine requirements Study current system Structure requirements and eliminate redundancies Requirement Analysis Functional requirements Performance requirements Generate alternative designs Compare alternatives Recommend best alternative 5/21
Phase 3: Design
Design How the system will accomplish this objective.
User interface Design Screen, Form, Report, and Dialog Design Data Design Data Element structure Design Process Design Program and Procedure Design 6/21
Phase 4: Implementation
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 7/21
Phase 4: Implementation
Conversion Parallel Strategy Run old & new systems for awhile to check validity. Safe.
Pilot Strategy Install in one part of organization at a time. Learn and adapt Phased Strategy In large system change one function at a time (e.g., order entry) Plunge Strategy Start using entire system. Can be dangerous if errors exist.
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Phase 5: Maintenance
Modification Modifying established system due to changes in the system for potential problems or necessary change.
Correcting errors Feedback
Managing Information Technology
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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 10/21
Motivation of RAD
Limitation of SDLC Pressures for businesses to speed up Shorter development lifecycles Competition in changing global environment
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Why wait 3 years to develop systems likely to be obsolete upon completion?
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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
The 4 Essentials of RAD (1/2)
Management Executives. Support for the RAD People Participation in JAD type Specialized team for RAD: SWAT
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Skilled With Advanced Tools
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Joint application design (JAD) - Group Decision Support System - Users, Managers and Analysts work together for several days - System requirements are reviewed - Structured meetings 13/21
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 14/21
RAD Life Cycle
Executives, managers, users determine requirements JRP workshops to agree requirements, overall planning JAD session to develop basis design CASE tool is used Generate code End users validate design Delivery of new system to users 15/21
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 16/21
Prototyping Examples
Graphic user interface: usually needs several modification to meet the user requirements Prototyping is similar to decide A completely operational prototype can be used as a pilot This girl is the user. Various designs of dresses are the Pilot Strategy Install in one part of organization at a time. Learn and adapt prototypes. If the user does not like the proposed one, developers do modification until it meets the user ’ s requirements.
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Prototyping Life Cycle
Prototype cycle 18/21
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 19/21
3 Types of System Development
Prototyping When requirements are hard to define RAD SDLC Hybrid type of SDLC and Prototyping Large and complex system 20/21
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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Special Thanks To
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MIS is one of the most appreciated course by the graduates
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POSMIS