SDLC - Spiral Model

Whenever the models are dependent on each other, in this case we develop the application part by part. For example: An application is divided into modules called module A, B, C, Spiral model is flexible for requirement changes. A software project repeatedly goes through each phases in iterations hence it is called spiral. By using spiral model customer can use the product at early stage.

In the spiral model the requirement is divided into sub modules as shown in above diagram these modules are depending on each other. For Module-A there will be separate requirement, design, coding, and testing, and each and every module will go through these phases cycle.

When to use Spiral model:

• Whenever there is long-term project then spiral model is useful
• Whenever user is not sure about their requirements
• When it is new product line
• If project is mission critical
• For medium to high-risk projects

 Advantages of Spiral model:

• Flexible for changes: Any time can requirement changes are possible
• Since it is module to module development, clarity in process
• Customer can use the product at early stages at least the basic models
• Since customer can get the product hence there will be approval and documentation control.
• Additional Functionality can be added at a later date.

Disadvantages of Spiral model:

• It is not suitable for short-term projects
• There are no parallel deliverables
• Can be a costly model to use
• If there is major issue time consumption will be more