Waterfall Model (Theory)

1.   Compare Waterfall Model vs. V Model (Difference & Similarities)

Waterfall Model

The waterfall model is a breakdown of project activities into linear sequential phases, where each phase depends on the deliverables of the previous one and corresponds to a specialization of tasks. It is also called a classical model used in system development life cycle to create a system with a linear and sequential approach. It is termed as waterfall because the model develops systematically from one phase to another in a downward way. All these phases are cascaded to each other in which progress is seen as flowing steadily downwards (like a waterfall) through the phases. The next phase is started only after the defined set of goals are achieved for previous phase and it is signed off, so the name "Waterfall Model". Let’s take a look at an example of a software engineering project plan using a waterfall model. In this example, we’ve scoped out tasks for adding a new app feature. When one task or milestone is complete, the next one begins. For example, deployment can’t happen until the Testing + Revision phase wraps. The following sequential phases are performed in waterfall model to complete any task or project.

Figure 1: Waterfall Model

 

 

1.     Requirement Analysis

The first phase in waterfall model which involves the understanding of what needs to be design and what is it function or purpose of the project is identified. Here, the specifications of the input and output are well documented, studied and marked which helps to understand the clear vision of the project for the future reference.

 

2.     System Design

The requirement specifications from the first phase are studied in this phase and system design is prepared. System Design helps in specifying hardware and system requirements and also helps in defining overall system architecture. The software code to be written in the next stage is created now.

 

3.     Implementation

With inputs from the system design, the system is first developed in small programs called units, which are integrated in the next phase. Each unit is developed and tested for its functionality, which is referred to as Unit Testing.

 

4.     Testing & Integration

All the units developed in the implementation phase are integrated into a system after testing of each unit. The software designed, needs to go through constant software testing to find out if there are any flaws or errors. Testing is done so that the client does not face any problem during the installation of the software. Because of every time interaction with the clients/users, the software will be good in quality in a quantitative way.

 

5.     Deployment

Once the functional and non-functional testing is done; the product is deployed in the customer environment or released into the market. First, we can deployed the different version of the product to the public for testing purpose. After received the good feedback, then we could deploy the full product to the market for publicly use.

 

6.     Maintenance

After deployment of the product into the market, there are some issues which would come up in the client environment. Such changes occur either from customer-initiated demands for improvement, or from vulnerabilities found during the system's live use. To fix those issues, patches are released. Also to enhance the product some better versions are released. That’s why, maintenance is done to deliver these changes in the customer environment.

 

 

V. Model

 

The V-model is a type of SDLC model where process executes in a sequential manner in V-shape. It is also known as Verification and Validation model. It is based on the association of a testing phase for each corresponding development stage. Development of each step directly associated with the testing phase. The next phase starts only after completion of the previous phase i.e. for each development activity, there is a testing activity corresponding to it.

Here it corresponds the two main factors in this model. One is Verification, which involves static analysis technique (review) done without executing code. It is the process of evaluation of the product development phase to find whether specified requirements meet.

And another is Validation, which refers to the dynamic analysis technique (functional, non-functional), testing done by executing code. Validation is the process to evaluate the software after the completion of the development phase to determine whether software meets the customer expectations and requirements.

So V-Model contains Verification phases on one side of the Validation phases on the other side. Verification and Validation phases are joined by coding phase in V-shape. Thus it is called V-Model.

Figure 2: V-Model

 

1.     Business Requirement Analysis

This is the first phase in the development cycle where the product requirements are understood from the customer’s perspective. This phase involves detailed communication with the customer to understand his expectations and exact requirement. This is a very important activity and needs to be managed well, as most of the customers are not sure about what exactly they need. So, this stage is also known as main Requirement Gathering stage.

 

2.     System Requirement Specification

Once you have the clear and detailed product requirements, it is time to prepare the complete system requirement. The system requirement specification will have the understanding and detailing the complete hardware and communication setup for the product under development. The system test plan is also developed based on this phase.

 

3.     High Level Design (Architectural Design)

Architectural specifications are understood and designed in this phase. Usually more than one technical approach is proposed and based on the technical and financial feasibility the final decision is taken. System design is broken down further into different modules taking up different functionalities. The data transfer and communication between the internal modules and with the outside world (other systems) is clearly understood.

 

4.     Low Level Design (Module Design)

In this phase the system breaks down into small modules. The detailed design of modules is specified, that’s why it called low level design. It is important that the design is compatible with the other modules in the system architecture and the other external systems. Unit tests which helps to eliminate maximum faults and errors at the early stage in the system, can be designed at this stage based on the internal module designs.

 

Validation Phases

The different validation phases in the V-Model are explained in details below:-

 

1.     Unit Testing

Unit tests designed in the module design phase are executed on the code during this validation phase. Unit testing is the testing at code level and helps eliminate bugs at an early stage, though all defects cannot be uncovered by unit testing.

 

2.     Integration Testing

After completion of unit testing Integration testing is performed. In integration testing, the modules are integrated and the system is tested. Integration testing is performed on the Architecture design. This test verifies the communication of modules among themselves.

 

3.     System Testing

System testing is directly associated with the system design phase. System tests check the entire system functionality and the communication of the system under development with external systems. Most of the software and hardware compatibility issues can be uncovered during this system test execution. It also tests the functional and non-functional requirements of the developed application.

 

4.        User Acceptance Testing (UAT)

UAT is associated with the business requirement analysis phase and involves testing the product in user environment that resembles the production environment. UAT verifies that the delivered system meets user’s requirement and system is ready for use in real world.

 

 

Comparison between Waterfall & V. Model

 

Basis	Waterfall Model	V. Model
Cost	The cost of waterfall model is low.	This model is expensive.
Simplicity	It is simple and straight forward model.	It is little hard to implement & understand than waterfall.
Flexibility	Flexibility of this model is Rigid.	Little more flexible than waterfall.
Process	It is a sequential Model Process.	It is also a sequential Model Process.
Way of execution	Steps move in a linear continuous way.	Steps move in simultaneous process.
Re-usability	Re-usability is limited.	Can re-use for some extent to.
User Involvement	Only in the beginning.	Only in the beginning too.
Testing	Testing only performs after the development.	Testing performs and planning in every phase.
Durability	Guarantee of success rate is low.	Guarantee of success rate is high.
Debugging rate	Software made using Waterfall model, the number of defects are less in comparison of software made using V-model.	Software made using V-model, the number of defects are greater in comparison of software made using Waterfall model.
Requirement Specification	Requirement Specification is necessary in the beginning.	Requirement specification is also necessary in the beginning.
Used Criteria	Less used nowadays.	Widely Used than the waterfall model.

 

Bibliography

TeamGantt. https://teamgantt.com. [Online]

ToolsQa. https://www.toolsqa.com. [Online]

Tutorials Point. https://www.tutorialpoint.com. [Online]

WiKiPedia. https://www.wikipedia.org. [Online]