SDLC Models: Introduction of SDLC Models and Various Models, Waterfall Model

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Introduction of SDLC Models

There are various software development life cycle models defined and designed which are followed during the software development process.

Various Models

  • Waterfall Model
  • Iterative Model
  • Spiral Model
  • V-Model
  • Big Bang Model
  • Unified Process Model

There are the models or way through which the process of SDLC will be executed in proper manner in order to get the desired results.

Waterfall Model

  • If once, steps implemented cannot return to previous results.
  • It is non-iterative sequential and linear model which is used for software development. It follows top-down approach.
Illustration: Waterfall Model

Features

  • Earliest Model (Classic Life Cycle Model)
  • Sequential Model (Linear Cycle Life Cycle Model)
  • Every phase must be implemented and completed before going to start the next step or phase
  • It is easy to understand and implement the process
  • It can be used, if requirements are already very well defined (Pre-defined)
  • Requirements of customer must be clear and must not be ambiguous.
  • Helpful in short Project/assignment having small budget.
  • Less risk in this model.

Iterative Model

Iterative model means the model that follows repeated cycles, repeatedly in order to develop a complete system. It will implement small portions at a time which can also be called as the incremental phases are followed in the iterative model.

Working

  • It follows the waterfall model but in iterative process.
  • We get a deliverable product at the end of completion of each cycle that can be core product in the starting level.
  • The core product which is developed can be shown to customer in order to get some feedback to improve the product further.
  • It follows linear and parallel workflow.

Advantages and Disadvantages of Iterative Model

Advantages
  • It is more flexible and efficient as compared to waterfall model.
  • Changes from the customer side can be easily accommodated in the project in the incremental phase, so that best results can be taken next time.
  • Better risk Analysis.
Disadvantages
  • Documentation work is high.
  • Customer involvement is required in linear approach.
  • As we need to integrate the phase or cycles, thus this can be an issue and overall costing of the project will be high.
Illustration: Disadvantages

Spiral Model

  • The spiral model was proposed by BOHEM in 1985. it is called spiral model because of its Spiral shape.
  • Spiral model is one of the most important Software Development Life Cycle models, which provides support for risk handling.
  • The spiral model is used for large projects requiring frequent enhancement. It is not used in small projects and this model is very expensive.

The Spiral Model Has Four Phases

  • Planning
  • Risk analysis
  • Engineering
  • Evaluation
Illustration: The Spiral Model Has Four Phases

V-Model

It is called as V-Model because it follows verification and validation. Thus, also called as verification and validation model in software engineering. Thus, entire model is implemented in the V-Shape.

  • Verification: To check the software that whether it meets the required specification or not.
  • Validation: It is the process to check whether specification meet the customer needs and requirements.

Then only, it will be an efficient and best quality software. Most important thing is that, this model follows both V՚s i.e.. , verify and validate in Parallel mock.

Illustration: V-Model

Big Bang Model

It is helpful when requirements are not clear at the starting. In this model all modules are tested individually, then finally constructed as complete system and it will be tested later. It comes under integration testing technique.

Advantages

  • It needs least planning.
  • It does not follow any formal method.

Disadvantages

  • Suits only small short projects.
  • Not good for complex software.
  • It does not fulfill the requirement of object-oriented programming.
Illustration: Disadvantages

Unified Process Model (Rational Unified Model)

It is also called as unified software development process. It creates a blue print of the organization for the software system.

It includes:

  • Programming language
  • OS
  • Frameworks and Servers required etc.

Features

  • It is iterative
  • It is incremental software development process framework.
  • It is an architecture centric software development model.
  • Cases are often used in this process.
  • It can implement object-oriented software.
  • Customization and changes are easily to be done.

Phases

  • Inception
  • Elaboration
  • Construction
  • Transition
  • Production

MCQs

Q.1. : Identify the false statement.

Statement P: Validation: To check the software that whether it meets the required specification or not.

Statement Q: Verification: It is the process to check whether specification meet the customer needs and requirements.

(1) P only

(2) Q only

(3) Both P and Q

(4) Neither P nor Q

Answer: (4) Neither P nor Q

Q.2. : Which of the following statement is not the benefit of using Iterative Model?

(1) It is more flexible and efficient as compared to waterfall model.

(2) Changes from the customer side can be easily accommodated in the project in the incremental phase, so that best results can be taken next time.

(3) Reduced risk analysis

(4) Both 1 and 2

Answer: (4) Both 1 and 2

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✍ Mayank