Introduction to software development life cycle (SDLC)

Generally in all other model we begin the process with a complete requirements specification. But in the Iterative model does not attempt to begin with a  complete specification of requirements and the iterative process begins with a very small part of  implementation of the requirements and enhances the versions iteratively until the implementation of the system completes and ready to be deployed and each iteration produces a new version of the product at the iteration end of the model.

Iterative model Diagram:

In this model, we create a piece of product in first iteration, then after reviewing it  will improve it in upcoming iterations until we get proper get particular product.

Example:

As shown in the above diagram in the first iteration the whole triangle is sketched lightly, in the iteration second lightly colors are filled and in the iteration third finishing is done. Here whole product is developed part by part in iterative model.

When to use iterative model:

• Whenever there is larger project i.e. with number of modules.
• Only some important requirements are defined and some other details can evolve with time.
• When the system has clear and completely defined requirement

Advantages:

• In the early stage of the life cycle, we can develop and make few functionalities works quickly.
• Requirements changes are allowed
• It supports changing requirements
• Application is produced at early stage where customer can evaluate and give the feedback.
• Suitable for complex and larger projects. Example: mission-critical / life critical projects.
• Changes / Modifications in the requirement is not much costlier
• In this model we can measure the progress
• Since this has iteration process, testing and debugging is easier
• We can plan for parallel development

 Disadvantages: 

• It is not suitable for smaller projects
• Progress of Project is mainly depends upon the risk analysis.
• For risk analysis, experience skilled resources are required.
• Requires more number of resources.
• An iteration of each phase is rigid

In the next chapter we will touch on Big Bang Model