software development life cycle 123344

8/8/2019 Software Development Life Cycle 123344

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Software Development LifeCycle


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Th e Water Fall Model


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Water Fall Model

In general it includes several phases:-Step1:Requirement analysisStep2:DesignStep3:CodingStep4:TestingStep5:Operation & maintance

1. Requirement analysis: All requirements has to bedefined in this step. Functional, non-functional &requirements must be specified at this stage.

2 . Design: This involves designing software along withD ata & Architectural details have to be emphasizedin this phase. This crucial as future of s\w productworks on the basis of design.


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Water Fall Model

3. Coding: C odification of program to achieve requiredoutput is essential. Selecting suitable language for theproject.

4. T esting: All the units & modules developed must beI ntegrated & system testing has to be performed.Testing aims to uncover all the errors.

5 . Operation & Maintance: Also called post installation

phase. It involves maintenance of s\w after installation.developing software is not important, but maintaing isvery crucial.

Advantages:Simple, systematic & easy to implement.

Demerits:It is suitable for enhancement of existing model but not for new.


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Spiral Model


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Spiral Model

This model was proposed by B ohem . It combinesdevelopment activities with risk management tominimize & control risk. It accommodate anydevelopmental model. It consists of 4 sectors

1) Obj ective setting: H ere objective of project phaseis determined . C onstrains on product are identified &detailed management plan is drawn. Project risk are

identified .2) Risk assessment & reduction: F or each identified risk a detailed analysis is carried out, steps are takento reduce risk .

3) Development & validation: After evaluation,adevelopment model for system is chosen. The decisionof choosing model is guided by risk factor.


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Spiral Model

E x:If user interface risk are dominate, evolutionaryprotyping might be appropriate.

4) Planning: It involves reviewing the result of stage preceding , weather to continue further loop of spiral.If decided to cont. plans are drawn to next phase .

Merits: It is risk driven process model.Risk are explicitly accessed and resolved thoughtthe process.

Demerits: Risk assessment could cost more thandevelopment. Applicable only to large systems.


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Iterative En h ancement Model


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Iterative model helps to remove the demerits of waterfall model. The phase of s/w development issame, but construction and & delivery is donerepetitive mode .In 1 st Iteration ,a less capable product are deliveredfor use. This product satisfies only a subset of requirements.

In next I teration , product with I ncremental feature isdeveloped. E very Iteration consists of all waterfallmodel. The complete product is divided into number of releases. The developed product is released oneafter another.


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This model repeats the activate of specification,development & validation . I nitially the system isdeveloped from abstract specification , which arethen refined with specification from the inputsobtained from the customer.


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Advantages:

It is used when less manpower is available for softwaredevelopment & release deadlines are tight.It is best suited for product development where it isensured that user has something to start with it.Disadvantages:Iteration may never end & the user may have endlesslyWait for final product.The cost estimation is also high .


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TH ANK Y OU

software development life cycle 123344

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