What is the difference between waterfall model iterative waterfall model prototyping model and spiral model?

Answer 1

The Waterfall model is a linear sequential approach to software development in which each phase of the development process must be completed before moving on to the next. The Iterative Waterfall model is similar to the Waterfall model, but includes a feedback loop in which each phase is revisited and revised based on feedback from the previous phase.

The Prototyping model is an iterative approach to software development in which a prototype is created and refined based on feedback from users and stakeholders. This model is often used for projects with high levels of uncertainty or where requirements are not well-defined.

The Spiral model combines elements of both the Waterfall and Prototyping models, with each iteration of the development process consisting of four phases: planning, risk analysis, engineering, and evaluation. This model emphasizes risk management and allows for flexibility and adaptation throughout the development process.

Overall, the main differences between these models lie in their approach to project management and development, with each model offering its own set of advantages and disadvantages depending on the specific needs of the project.

Answer 2

There are 2 main methods of software modeling

· Predictive(e.g.waterfall) - Good when requirements are well understood and have low technical risk.

· Adaptive(e.g.spiral) - Good when requirements and needs are uncertain. High technical risk

In a failure - In a predictive LC it will be expensive because we get to know the failure after finishing everything but in adaptive LC only an iteration is wasted.

There several phases in the waterfall model

a. Planning

b. Requirements

c. Specification (b and c together we call analysis)

d. Design

e. Implementation

f. Maintenance

This is called a Functional Decomposition and also a top down approach (Where we see from above and identify the big picture first and then go in to higher details)

In the waterfall model, before going to the next phase we have to freeze the previous step (no turning back). This is good when we have a good understanding about the project at the beginning.

But iterative models gives us more flexibility through giving chance to revisit early phases. Spiral model is a adaptive model.

This is an adaptive SDLC that cycles over and over again through development activities until project is complete. Here we go through some major steps,

1. Plan

2. Analyze and Design

3. Construct prototype

4. Test and integrate

These steps iterate till completion of the project. This is also can be viewed as a divide and conquer approach. In first few iterations complex or risky parts of the system are handled.