Question

CPSC 362 Foundations of Software Engineering - Chapter 2-3 Below is the simple process model. What development activity would you choose to add first to this process and why? Problem statement Code Compile Unit test Release Problem Problem Debug A simple process. Discuss advantages and disadvantages of the waterfall process model. What does it mean for a process to be iterative and incremental? What is the difference between the evolutionary prototyping life cycle model and simple process model (code and fix)?

Answer 1

1>> In the given Simple Mode in the figure, I would like to add Requirements Gathering and Analysis after the Problem Statement. Because we know the problem description and we need to derive the requirements using the given data so this phase is needed.

2>> Advantages of waterfall model

• This model is simple and easy to understand and use.
• It is easy to manage due to the rigidity of the model – each phase has specific deliverables and a review process.
• In this model phases are processed and completed one at a time. Phases do not overlap.
• Waterfall model works well for smaller projects where requirements are clearly defined and very well understood.

Disadvantages of waterfall model

• Once an application is in the testing stage, it is very difficult to go back and change something that was not well-thought out in the concept stage.
• 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.

3>> An Iterative process is one that repeats a series of operations cyclically, with the intention of coming closer and closer to some desired result. In mathematics, for example, the Newton-Raphson method is used to approximate the solutions to algebraic equations. Often a direct solution of an equation is difficult to obtain: sometimes there is no known way to so. But it is often possible to approximate a solution, essentially by trying a value, and then repeatedly using that value to get a more accurate solution. If the calculation of the new approximation is easier than finding a direct solution, iteration is worthwhile.

An Incremental approach to producing something can be seen as producing more and more of it each time. This is in a bit of contrast to the notion of an iterative approach, which is best viewed as producing an improved version of some targeted solution. An incremental approach produces a new thing by changing the old one.

4>> Evolutionary Prototyping Life cycle model is a combination of Iterative and Incremental model of software development life cycle. Delivering your system in a big bang release, delivering it in incremental process over time is the action done in this model. Some initial requirements and architecture envisioning need to be done.

It is better for software products that have their feature sets redefined during development because of user feedback and other factors. The Evolutionary development model divides the development cycle into smaller, incremental waterfall models in which users are able to get access to the product at the end of each cycle.

Feedback is provided by the users on the product for the planning stage of the next cycle and the development team responds, often by changing the product, plan or process. Therefore, the software product evolves with time.
All the models have the disadvantage that the duration of time from start of the project to the delivery time of a solution is very high. Evolutionary model solves this problem in a different approach.

Evolutionary model suggests breaking down of work into smaller chunks, prioritizing them and then delivering those chunks to the customer one by one. The number of chunks is huge and is the number of deliveries made to the customer. The main advantage is that the customer’s confidence increases as he constantly gets quantifiable goods or services from the beginning of the project to verify and validate his requirements. The model allows for changing requirements as well as all work in broken down into maintainable work chunks.

Application of Evolutionary Model:

1. It is used in large projects where you can easily find modules for incremental implementation. Evolutionary model is commonly used when the customer wants to start using the core features instead of waiting for the full software.
2. Evolutionary model is also used in object oriented software development because the system can be easily portioned into units in terms of objects.

A Simple process model 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 fully before the next phase can begin. This type of software development model is basically used for the project which is small and there are no uncertain requirements.

• Phases in this model are processed one at a time.
• Each stage in the model is clearly defined.
• This model has very clear and well undestood milestones.
• Process, actions and results are very well documented.
• Reinforces good habits: define-before- design,
  design-before-code.
• This model works well for smaller projects and projects where requirements are well
  understood.