Evolutionary/model (SDLC)

By: Anthony GeorgeChristian Loregnard

Validation Finalversion

DevelopmentIntermediateversions

SpecificationInitialversion

Outlinedescription

Concurrentactivities

Diagram

Main characteristics:The phases of the software construction are interleavedFeedback from the user is used throughout the entire processThe software product is refined through many versions

Main characteristics:◦ The phases of the software construction are interleaved◦ Feedback from the user is used throughout the entire

process◦ The software product is refined through many versions

PhasesDefine the basic requirementsCreate a working prototypeVerification of prototypeEvaluate and deliberate

. Advantages◦ Deals constantly with changes◦ Provides quickly an initial version of the system◦ Involves all development teams

Characteristics

◦ Quick fixes may be involved◦ “Invisible” process, not well-supported by documentation◦ The system’s structure can be corrupted by continuous change

Applicable◦ When requirements are not well understood◦ When the client and the developer agree on a “rapid

prototype” that will be thrown away◦ Good for small and medium-sized software systems

Disadvantages

Requirements planning phase (a workshop utilizing structured discussion of business problems)

User design phase – users to participate in the nontechnical design of the system

Construction phase – productivity tools, such as code generators, screen generators.

Cutover phase -- installation of the system, user acceptance testing and user training

Phases of Rapid Application Development (RAD)

RAD Diagram

Requirements planning phase

User design phase

Construction phase

Cutover phase

Pro

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Reduced cycle time and improved productivity with fewer people means lower costs

Customer involved throughout the complete cycle minimizes risk of not achieving customer satisfaction and business needs

Focus moves from documentation to code

Strenghts

Accelerated development process must give quick responses to the user

Requires a system that can be modularized Developers and customers must be committed to

rapid-fire activities in an abbreviated time frame. May compromises functionality and performance

in exchange for faster development and better application maintenance

Weaknesses

When requirements are not fully understood.User involved throughout the life cycleFunctionality delivered in incrementsHigh performance not requiredSystem can be modularized

Sources Ian Sommerville, Software Engineering, 8th

Ed., Addison-Wesley, 2006 John Petlicki of DePaul University, USA

Applicable