Various Software Development Model Waterfall Model V model etc

Hello friends
In this Article we will learn that how many working software models are being used in IT industries also what all the drwabacks they have and why do have many Software Development models?? due to usage or need of business requirement we use different models:-
1). WaterFall Model :- The Waterfall Model was the first Process Model to be introduced. It is also referred to as a linear-sequential life cycle model. It is very simple to understand and use. In a waterfall model, each phase must be completed before the next phase can begin and there is no overlapping in the phases.

The Waterfall model is the earliest SDLC approach that was used for software development.

The waterfall Model illustrates the software development process in a linear sequential flow. This means that any phase in the development process begins only if the previous phase is complete. In this waterfall model, the phases do not overlap.

Waterfall model is an example of a Sequential model. In this model, the software development activity is divided into different phases and each phase consists of a series of tasks and has different objectives.

Waterfall model is the pioneer of the SDLC processes. In fact, it was the first model which was widely used in the software industry.

Prototype Model :-

Prototype model should be used when the desired system needs to have a lot of interaction with the end users. Typically, online systems, web interfaces have a very high amount of interaction with end users, are best suited for Prototype model.
Prototyping is defined as the process of developing a working replication of a product or system that has to be engineered. ... In this process model, the system is partially implemented before or during the analysis phase thereby giving the customers an opportunity to see the product early in the life cycle.
This model is flexible in design.
It is easy to detect errors.
We can find missing functionality easily.
There is scope of refinement, it means new requirements can be easily accommodated.
It can be reused by the developer for more complicated projects in the future.

Incremental and Iterative Approach
•In incremental development, the product is built through successive versions that arerefined and expanded with each iteration–
Three concepts underlie the incrementalapproach:
•The Initialization Step
•The Control List
•The Iteration Step


Throwaway Approach
•In the incremental approach,
–the initial prototype is revised and refinedrepeatedly until it becomes the final product.

•In the throwaway approach,
–the prototype is discarded after the stakeholdersin the development are confident that they havearrived at the correct specifications and thedevelopment on the “real” product can start.

Incremental Model :- The incremental build model is a method of software development where the product is designed, implemented and tested incrementally until the product is finished. It involves both development and maintenance. The product is defined as finished when it satisfies all of its requirements.
Incremental Model is a software development process where requirements are divided into several stand-alone software development modules. In this example, each module passes through the requirement, design, development, implementation, and testing phases.

This model can be used when the requirements of the complete system are clearly defined and understood. Major requirements must be defined; however, some details can evolve with time. There is a need to get a product to the market early. A new technology is being used.

2). Spiral Model :- The spiral model combines the idea of iterative development with the systematic, controlled aspects of the waterfall model. This Spiral model is a combination of iterative development process model and sequential linear development model i.e. the waterfall model with a very high emphasis on risk analysis. It allows incremental releases of the product or incremental refinement through each iteration around the spiral.

The spiral model is a risk-driven software development process model. Based on the unique risk patterns of a given project, the spiral model guides a team to adopt elements of one or more process models, such as incremental, waterfall, or evolutionary prototyping
Spiral Model - Design The spiral model has four phases. A software project repeatedly passes through these phases in iterations called Spirals.
Identification
This phase starts with gathering the business requirements in the baseline spiral. In the subsequent spirals as the product matures, identification of system requirements, subsystem requirements and unit requirements are all done in this phase. This phase also includes understanding the system requirements by continuous communication between the customer and the system analyst. At the end of the spiral, the product is deployed in the identified market.

Design
The Design phase starts with the conceptual design in the baseline spiral and involves architectural design, logical design of modules, physical product design and the final design in the subsequent spirals.

Construct or Build
The Construct phase refers to production of the actual software product at every spiral. In the baseline spiral, when the product is just thought of and the design is being developed a POC (Proof of Concept) is developed in this phase to get customer feedback. Then in the subsequent spirals with higher clarity on requirements and design details a working model of the software called build is produced with a version number. These builds are sent to the customer for feedback.

Evaluation and Risk Analysis
Risk Analysis includes identifying, estimating and monitoring the technical feasibility and management risks, such as schedule slippage and cost overrun. After testing the build, at the end of first iteration, the customer evaluates the software and provides feedback.

The following illustration is a representation of the Spiral Model, listing the activities in each phase.

.

3). V Model :- In software development, the V-model represents a development process that may be considered an extension of the waterfall model, and is an example of the more general V-model. Instead of moving down in a linear way, the process steps are bent upwards after the coding phase, to form the typical V shape.
V Model is a highly disciplined SDLC model in which there is a testing phase parallel to each development phase. The V model is an extension of the waterfall model in which testing is done on each stage parallel with development in a sequential way. It is known as the Validation or Verification Model.
The V-model is a graphical representation of a systems development lifecycle. It is used to produce rigorous development lifecycle models and project management models.
What is V & V Testing??
In software project management, software testing, and software engineering, verification and validation (V&V) is the process of checking that a software system meets specifications and that it fulfills its intended purpose. It may also be referred to as software quality control.

4). Agile Model :- Agile SDLC model is a combination of iterative and incremental process models with focus on process adaptability and customer satisfaction by rapid delivery of working software product. Agile Methods break the product into small incremental builds. These builds are provided in iterations.
Agile modeling is a methodology for modeling and documenting software systems based on best practices. It is a collection of values and principles, that can be applied on an software development project.
Well executed Agile software development methodology helps teams significantly improve the quality of their software at each release. Not only that, it allows teams to adapt to change quickly. The Agile process consists of short, time-boxed iterations known as sprints. Each sprint results in a working product.
The 12 Agile Principles: What Are They and Do They Still Matter? Early and Continuous Delivery of Valuable Software. ...
Embrace Change. ...
Frequent Delivery. ...
Business and Developers Together. ...
Motivated Individuals. ...
Face-to-Face Conversation. ...
Working Software. ...
Technical Excellence.