software development life cycle models

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Software Development Life Cycle Models : 

Software Development Life Cycle Models By Hiren Sardhara

Process Models : 

Process Models A software process model is an abstract representation of a process Each s/w process can be defined in a variety of ways using text, figures or combination of both S/w engineers have developed various formats for processing the description of a s/w process known as the process models

Examples of software process model : 

Examples of software process model Waterfall model Evolutionary development Formal transformation System assembly from reusable components

Waterfall Model : 

Waterfall Model

Waterfall Model Process : : 

Requirements – defines needed information, function, behavior, performance and interfaces Design – data structures, software architecture, interface representations, algorithmic details Implementation – source code, database, user documentation, testing Testing – Ensure that the s/w requirements have met Maintenance – keep s/w operational after delivery to the client Waterfall Model Process :

Waterfall Demerits : 

Waterfall Demerits Waterfall Merits All requirements must be known upfront Can give a false impression of progress Does not reflect problem-solving nature of software development – iterations of phases Easy to understand, easy to use Provides structure to inexperienced staff Milestones are well understood Sets requirements stability

Spiral model : 

Spiral model

Spiral model process : : 

Objective settings:- objective of the project phases are determined Risk assessment and reduction:- detailed analysis of project is carried out Development and validation:- developed model is guided for risk factors Planning:- it involves reviewing the results of the preceding stages and a decision is made Spiral model process :

Spiral Model Weaknesses : 

Spiral Model Weaknesses The model is complex Risk assessment expertise is required Spiral may continue indefinitely Developers must be reassigned during non-development phase activities Provides early indication of insurmountable risks, without much cost Users see the system early because of rapid prototyping tools Critical high-risk functions are developed first The design does not have to be perfect Spiral Model Strengths

Evolutionary development : 

Evolutionary development Evolutionary development is based on the idea of developing an initial implementation, exposing this to user computer and refining it through many versions until and acceptable system has been developed

Merits of Evolutionary model : 

Merits of Evolutionary model Requirements are not frozen in beginning New features can be added to the system This approach is useful for the systems where it is impossible to express detailed specification Demerits of evolutionary model Poority structured system Invisible process Need of skilled staff