Agile and V model of SDLC.

In this tutorial we are going to learn about the Software Development Life Cycle, which includes the following topics:-

. Iterative model 

. When to use Iterative Model

. Advantages/Disadvantages of Iterative model

. Spiral model

. When to use Spiral Model

. Advantages/Disadvantages of Spiral model

The Fifth model of SDLC is "Iterative Model". This is the Fifth model of SDLC after Spiral model. This model is also called as Incremental model .Let us discuss about the Iterative model in Detail :-

Iterative model :-

Software development with the help of this model leads to a development process in iterations.Incremental development divides the system functionality onto portions basically called increments.It is the process of develop the software in increments. At first, the process is developed at very small scale by following all steps into consideration.These process groups Iteration into phases. i.e. inception, elaboration,constructions and transition.Every cycle produces a software which is complete in itself having more features and are more capable of from the previous version. let us see all one by one.

When to use iterative model:

1)When  requirement of system are clearly understood.

2)When early demand release of real product arises.

3)When high risk features or goals are involved.

4) Mostly used in product based companies or Web applications.

Advantages of Iterative model:-

1) The Software will be generated quickly during SDLC.

2) Its flexible and less expensive to change the requirement and scope.

3)This model is less costly if we compares with other models in SDLC

4) Errors can easily be verified.

5)Customer can respond to each building

Disadvantages of Iterative model:-

1) It requires a good planning and design.

2)Each iteration phase is rigid and does not overlap.

3)Its very time consuming to rectify a problem and correct in one unit.

4) Problems might comes due to system architecture. 

i)It identifies the project scope,both functional and non-functional requirements and also it identifies the risks at high level.

ii) Elaboration delivers a working architecture that reduces the top risks and fulfills the non-functions requirement.

iii)Construction incrementally fills in the architecture with the codes which are ready for productions from analysis, design,implementation and testing of the functional requirement.

iv) Transition delivers the system into the operating environment production team.

Spiral model:-Spiral model is the combination of  waterfall and iterative model. It was first mentioned by Barry Boehm in 1986.It is risk driven development process model.Based on unique risk patterns , this model guides a team to adopt elements of one or more process models.

When to use Spiral Methodlogy:-

1) When project is large.

2)When releases are frequently required

3)When creation of prototype is applicable

4)When risk and cost evaluation is important .

5)For medium to high risk projects

6)When requirements are complex and unclear

7) When changes may require at any time

Advantages of Spiral model:-

1) Development is fast and features is added in systematic way.

2) There is always a space fr customer feedback

3) Risk management is managed by repeated development

4) Additional functionality or changes can be done at later stages if required.

5) Prototype building is done in small fragments so cost estimation becomes easy.

Disadvantages of Spiral model:-

1) Documentation is more as it has intermediate phases.

2) Not applicable for smaller project because it might cost company a lot.

3) Its needs to be followed strictly for smooth operation.

4)It has risk of not meeting the schedule or budget.

5) It works best only for large projects. 


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