- Waterfall Model
- pros
- cons
- Best Scenarios
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.
In 'The Waterfall' approach, the whole process of software development is divided into separate phases. In this Waterfall model, typically, the outcome of one phase acts as the input for the next phase sequentially. The squential phases in Waterfall Model are
Requirement Gathering and analysis
All possible requirements of the system to be developed are captured in this phase and documented in a requirement specification document.
System Design The requirement specifications from first phase are studied in this phase and the system design is prepared. This system design helps in specifying hardware and system requirements and helps in defining the overall system architecture.
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.
Integration and Testing
All the units developed in the implementation phase are integrated into a system after testing of each unit. Post integration the entire system is tested for any faults and failures.
Deployment of System
Once the functional and non-functional testing is done; the product is deployed in the customer environment or released into the market.
Maintenance
There are some issues which come up in the client environment. To fix those issues,it realeases chunks of code like patches. Also to enhance the product some better versions are released. Maintenance is done to deliver these changes in the customer environment.
Some of the major advantages of the Waterfall Model are as follows −
- Simple and easy to understand and use
- Easy to manage due to the rigidity of the model. Each phase has specific deliverables and a review process.
- Phases are processed and completed one at a time.
- Works well for smaller projects where requirements are very well understood.
- Clearly defined stages.
- Well understood milestones.
- Easy to arrange tasks
The major disadvantages of the Waterfall Model are as follows −
- No working software is produced until late during the life cycle.
- High amounts of risk and uncertainty.
- Not a good model for complex and object-oriented projects.
- Poor model for long and ongoing projects.
- Not suitable for the projects where requirements are at a moderate to high risk of changing. So, risk and uncertainty is high with this process model.
- It is difficult to measure progress within stages.
Ultimate aim of the software application is that end user will find it useful, intuitive to use and makes them more productive in their day to day work. If one follows a waterfall approach then user may not need those features at all or may need something different. There are more chances of getting wrong. Agile exists for a reason and IMO it's mostly commonsense.