System development models specify how the activities of the development process are organized in the total system development effort.
Each model is designed for a specific purpose or reason that follows a particular life cycle but each may have similar goals and a common task. There are four types of System Development Models
- Waterfall Model
- Prototype Model
- Spiral Model
- Iterative Model
The waterfall model describes a system development method that is linear and sequential in nature following gradually downward similar to waterfall.
It is easy to understand Problem definition, Feasibility Study, Requirement Analysis, System Design, Coding and Testing, Implementation, System Maintenance
A prototype is an early approximation of the final system or product. This mode is useful for systems where requirements are not known in detail during development.
In this model, customers can realize the system requirement after the prototype is brought into operation. It allows more accurate, flexible design and development. It takes a low cost in design and development time.
- Requirement Analysis Quick Design Prototype Building
- Engineer The Product Refine Prototype User Evaluation
It is an evolutionary model developed by Barry Boehm in 1986. Each iteration of the prototype is represented as a cycle in the spiral. This model is risk-oriented.
It is a combination of a Prototype Model and a Waterfall Model. This model is used for large expensive and complicated projects. Planning, Risk Analysis, Engineering, Construction and Release, Custom evaluation, Customer Communication
An iterative life cycle model does not attempt to start with a full specification of requirements.
Instead, development begins by specifying and implementing just part of the software, which is then reviewed in order to identify further requirements.