development-models

Waterfall

What is the waterfall model?

• The Waterfall Model is a sequential software development process divided into distinct phases

• Each phase must be completed before the next one begins

Steps

1. Requirement Gathering and Analysis: All possible system requirements to be developed are captured and documented clearly

2. System Design: The requirements are translated into a design. Architects and designers define the overall architecture and identify the main components

3. Implementation: The actual code is written in this phase based on the design documents, turning the system design into a functional program

4. Integration and Testing: All the components and modules are integrated and tested to ensure that the entire system works as expected

5. Deployment: The product is released to the market or handed over to the client. It may involve installation, customization, and training

6. Maintenance: Post-release, the system needs regular maintenance to fix bugs, improve performance, or add new features

The Waterfall Model in Software Engineering

Benefits and drawbacks

Suitability

• The Waterfall Model is most suitable for projects where requirements are well understood and unlikely to change

• It works well when high quality and compliance are essential, and there is a clear understanding of the project’s goals and constraints

Iterative (Agile)

What is the iterative model?

• The iterative model s a type of Agile software development methodology that promotes adaptability and high customer involvement

Steps

1. Identify user stories and requirements

   1. Work closely with stakeholders to gather functional and non-functional requirements

   2. Requirements are often written as user stories (e.g. As a user, I want to…)

2. Plan the sprint (Sprint Planning)

   1. Break down requirements into tasks

   2. Choose a set of tasks (features) for the current sprint (a short time-boxed development period, usually 1–4 weeks)

   3. Define the sprint goal

3. Design the solution

   1. Decide how the selected features will be built

   2. Focus is on simple and adaptable design, not heavy upfront documentation

4. Develop the features

   1. Write code for the selected tasks in the sprint

   2. Developers often work in pairs or small teams (e.g. pair programming)

5. Test continuously

   1. Perform unit testing, integration testing, and acceptance testing during the sprint

   2. Testing is ongoing, not saved for the end

6. Review progress (Sprint Review)

   1. Demo the working software to stakeholders

   2. Collect feedback and identify changes or improvements

7. Reflect on process (Sprint Retrospective)

   1. The team reflects on what went well and what needs improving in the next sprint

   2. Focus is on team performance and process optimisation

8. Release (may happen after every sprint or set of sprints)

   1. Deploy working software to users or staging environment

9. Repeat

   1. Move to the next sprint with updated priorities and feedback

Benefits and drawbacks

Suitability

• The iterative model is most suitable for small to medium-sized projects where requirements can change and customer involvement is high

Rapid Application Development (RAD)

What is RAD?

• Rapid Application Development (RAD) is a software development methodology that emphasises fast and iterative development

Steps

1. Requirement planning: Gather general system requirements, define constraints and assumptions

2. User design and prototyping: Collaborate with users to develop prototypes, ensuring alignment with user needs

3. Construction or iterative development: Build the system incrementally, with continuous user feedback and adaptation

4. Cutover or deployment: Transition the product into the live environment, including user training, support, and documentation

5. Maintenance and updates: Continue to adapt and improve the system based on user feedback and needs

Rapid Application Development (RAD) Model of Software Development

Benefits and drawbacks

Suitability

• Rapid Application Development is most suitable for projects where rapid delivery is required and where requirements can be developed and refined on the go