waterfall model | Different phases with advantages and disadvantages (2023)

Introduction to the waterfall model

The waterfall model is one of the earliest models of software development, where tasks are performed sequentially, starting from the top with feasibility and through various tasks with implementation into the live environment. Requirements feed into the design, which feeds into construction or implementation, and finally into testing. Since the testing process occurs at the end of the model, routing the feeds up the waterfall was a challenge.

To work on the waterfall model, we need to understand its application approach, which is based on both internal and external factors, which can be as follows:

• No ambiguous requirements in the application.
• Stability of the product definition.
• It's technology understood.
• It's not dynamic.
• Extensive resources with relevant expertise are available to support the product.
• Short length project.
• The good document, clear and firm requirements.

To begin the history of the waterfall model, I would like to say that the first example of the waterfall model was presented in a 1970 article by Winston w Royce. Since then, the waterfall model has said that one should not move to another phase until the previous phases have been fully tested, checked, and verified. It emphasizes the logical sequence of phase steps. Its operation is similar to water flowing over the edge of a cliff.

This software development approach is called waterfall because it systematically descends from one phase to the next. The waterfall model has been widely used in science since it was first published by Winston W. Royce in 1970area of ​​software development. In the software development process cycle, programming models are used to plan the various application phases. One such model is the waterfall model.

Phases of the waterfall model

Below are the phases of the waterfall model:

From the above infographics, we can understand that the waterfall model has a total of 7 phases of the design and development software cycle which are as follows:

1. Requirements
2. Analyse
3. Design
4. Coding / Implementation
5. To test
6. Operation / Deployment
7. maintenance

So we can see that the waterfall model works hierarchically from top to bottom, completing one phase with full verifications and then moving to another phase including phase processes like conception, initiation, analysis, design, construction, test, production/implementation and Maintenance. To get a concise knowledge of the waterfall model, we need to deeply understand its processes with its working model. A primary prerequisite phase must be understood before the deep phases of knowing begin. It is about the feasibility study for the software product. It addresses the financial and technical aspects of the project requirements. This phase is about correcting the measures based on the analyzed advantages and disadvantages. Thus, the best solution is chosen.

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1. Requirements

In particular, we need to know and understand what we need to design, what we need to develop, its processes, its functionality, etc. It provides input material for the product to be manufactured; This is how the upcoming product is examined, completed and marked. It also gives us the opportunity to determine the hardware or software requirements of the product that is designed, developed and captured at all stages.

2. Analyse

It leads to designing models, schemas and business rules.

Not only this requirement is divided into two parts:

• Requirements gathering and analysis:First, all information and requirements for product development are collected from the customer and prepared for analysis. The main task of this part is to eliminate incompleteness and inconsistencies related to software product development.
• Requirement Specifications:The requirements analyzed above are then documented in an SRS document (Software Requirement Specification). It serves as a link between the customer and the SRS development team. All future disputes will be managed and resolved solely through this SRS documentation.

3. Draft

After the first phase is completed and verified, this is the next most important phase to study as it is used for system design. It helps to specifysoftware and hardwareProduct design requirements. It also helps in the overall architecture of the system design. Therefore, in this phase, the requirements specification is mainly studied and verified. It is also helpful in transforming the SRS document into a functional design and developing the software product. So we can say that in the design phase one creates the overall architecture for the software development project.

4. Implementation

After the system design is fully verified, the implementation phase follows. In this phase, the inputs from the system design are taken over and initially developed in small programs, so-called units, which are tested and implemented in the next phase. Each unit in the implementation phase is developed and tested for full functionality, akaUnit-Tests. In this phase, the system design is implemented in source code with fully functional program modules. It includes the development, testing and integration of the software.

5. Integration and Testing

Each unit design and development in the earlier phases are picked up from the implementation phase which after testing each unit is integrated into a module or system for various tests like stress test, load test, etc. The test environment undergoes constant software testing to determine if there is any flow or flaws in the design or code. Testing is performed to maintain the stability and feasibility of the software so that the customer is not faced with glitches or bugs during production. In this phase, the entire system is thoroughly tested for errors and failures after implementation.

System tests consist of three different types of activities that can be specified below:

• Alpha (α)-Test:The tests performed by the development team.
• Beta (b)-Test:It's the tests done by a friendly team of customers and users.
• acceptance test:It is done afterAlpha-Tests und Beta-Tests. This happens after delivery by the customer. After the customer has performed tests, a decision is made whether to accept or reject this software. This is the phase in which errors are debugged.

6. System Provisioning / Operation

Once the non-functional, functional, alpha and beta tests are completed, the software product is deployed to the user's or customer's system or released to the market. The deployment phase includes installation, migration and support of the complete system in the user or customer environment.

7. Maintenance

It is the last but most important stage in the waterfall workflow model. This step occurs immediately after installation and includes making the appropriate change to the product or system, or improving, changing or modifying attributes related to performance issues related to the system. Its main task is to improve the performance of the system with the result of software output with maximum accuracy.

These changes made during the maintenance phase mainly relate to initiated changes to be made by the customer or users after the installation and testing phase, including bugs such as bugs revealed during live use of the system or requests made by customers. In this way, the customer receives timely and scheduled maintenance and support for the developed product. You will be amazed that the effort in the design and development phase of the software product is only 60% compared to the effort in the maintenance phase.

There are three types of maintenance given below:

• Corrective Maintenance:During the design and development phase, some errors are not discovered; they are only taken into account if the customer uses them. This is corrective maintenance only; H. fixing problems or bugs that were not discovered during the development phase.
• Perfect maintenance:This maintenance is carried out at the customer's request in order to expand and improve the functionalities of the system or the software.
• Adaptive maintenance:The maintenance required to change the system environment is usually needed to port the existing system to a new climate, computer or system, or possibly with a new operating system. This phase is too important as it leads to better system performance.

So, in the above discussion, we know well each phase of the waterfall model with complete specifications. So we can say that the waterfall model is very important in the software field compared to the mechanical industry because each phase has its own importance, resulting in a more productive and stable software.

Pros and cons of the waterfall model

Below are the advantages and disadvantages:

Advantages:

• It allows for departmental division and control.
• A timeline with deadlines can be set for each development phase, and a product can progress through the phases of the development process model in sequence.
• As it goes through stages that are easy to understand and explain, it overcomes many problems and makes it very easy to use.
• Due to the rigidity of the workflow model, it is very easy to manage as each stage in the waterfall model has specific review and delivery processes.
• The waterfall model works well for smaller projects where the requirements are very well understood.
• The schedule can be set with deadlines for each development phase, and a product can cycle through the phases of the development process model.
• Clearly defined stages.
• Well understood milestones.
• Easy to arrange tasks.
• Process and results are well documented.
• Reinforces good habits: define-before-design.
• Design-before-Code.
• The model works well for smaller projects and projects where the requirements are well understood.

Disadvantages:

• Not a good model for complex and object-oriented projects.
• Not suitable for projects with a medium to high risk of change.
• It is difficult to estimate the time and cost involved in each phase of the development process.
• Not a good model for complex and object-oriented projects.
• Working software is not produced until late in the life cycle.
• Cannot meet changing needs.
• It's not easy to measure progress within phases.
• High level of risk and uncertainty.
• Bad model for long and ongoing projects.
• Adjusting the scope during the lifecycle can kill a project.
• No feedback path.
• No phase overlap.
• Change requests can only be considered with difficulty.
• Risk and uncertainty are high with this process model.

Where to use the waterfall model?

Now that we've circled all the scenarios, we come to a point where we want to know where we can use the waterfall model.

• In a defense project, the waterfall model is mainly used. The requirement is clear because it analyzes them well before moving to the development phase.
• This can also be used in migration projects where the requirements are just the same platform or the languages ​​may vary/change.

Diploma

So, overall, we can say that waterfall model is most suitable for small software development projects compared to large projects because design, development and implementation in small project is easier when working on waterfall model. Finally, in this model, all previous phases must be completed when moving to the coming phases. So, for large projects, the problems and errors are common because it is a large model. The testing phase continues every time it is implemented by the waterfall model, resulting in less optimization and accuracy of the software.

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