Individual Assignment

The two software development methodologies that I have selected for this assignment are the Waterfall Model (as chosen by you) and the Spiral model (chosen by me).

These two methods often cause confusion amongst software developers as they are unable to decide which of the two is better for the software they are developing.

The first software model to be used was the waterfall. The spiral, that came later, is one of the most popular models in the field of software development.

I will go further into each of the above mentioned two models after I describe the four laws given in the prescribed text.

I will start with the Glass Law (dubbed law 1). If I was to describe the Glass law, I would say in a nutshell, requirements are the foundation of any project, and incomplete or misinterpreted or misjudged requirements are the key to failure.

What I mean by the above is that when the requirements are not clarified, incomplete, unstable or far too many to cope with, the project will face a high chance of failure.

A real world example, which added approximately $560M USD to the cost of the airport and became a modern era example of Glass law, was originally planned to automate the handling of baggage through the entire airport, but due to underestimation of complexity, changes in requirements, underestimation of schedule and budget and other causes was a drastic failure.

Moving to Boehm’s laws, the first and second law complement each other in a way.
The first law states that errors happening during the requirement and design period of a project become harder and more expensive to be fixed as the project advances.
In a nutshell, what Boehm implies in his first law is the sooner you detect an anomaly or issue in your system, the easier and cheaper it is to fix it or change it.

A simple example of this would be the implementation of new systems within big retail outlets and chains without training the staff and getting any input from them. This will cause cues at checkout counters and errors in the stock taking process.

Boehm’s second law states that prototyping significantly reduces the amount of errors that can occur during the design and requirements collecting phases. A simple explanation would be that requirements and design phases do not need to be entirely theoretical, instead performing prototyping as part of those phases will aid in the success of the project during the implementation time.

Boehm was the creator of the Spiral model, which I will explain in detail later and use as one of the models for this assignment.

Moving on to Constantine’s law, TO BE CONTINUED….

Moving on from the Waterfall and Spiral methodologies that will be used in this assignment. I will start with describing each of them as clearly and simply as possible.

The Waterfall model is often referred to as the linear and sequential model, for the flow of activities in this model are rather linear and sequential as the name suggests. In this model, the software development activities move to the next phase only after the activities in the current phase are over. However, once you have moved to the next phase, you cannot return to the previous one; basically you can go in one direction REQUIREMENTS only. The phases of this model are: * The Waterfall Model
Requirement Gathering * ANALYSIS
Analysis Phase * Design Phase * Coding Phase * DESIGN
Testing and Debugging Phase * Delivery Phase
CODING

TESTING

DELIVERY

The most important advantage of the waterfall model lies in the fact, that there is minimum planning overhead for the steps that are to follow. There is certain amount of discipline that is enforced as one has to only look into one phase of the process at any given point of time. The most important advantage is that the project does not slip on its schedule. The number of resources working on the project does not keep on increasing with each passing day, as the planning for the same is done at the start of the phase itself.
As anything in life, there are disadvantages to this model. The first and the foremost disadvantage is the inability of making changes to the system, once the system requirements have been frozen. In other words, one cannot go back to the previous stage.

The spiral model was introduced by Barry Boehm, due to the shortcomings in the waterfall and prototype models of software engineering. It is a combination of the said two models of software development. From the name of the model, it can be derived that the activities of software development are carried out like a spiral. The phases of the spiral model are as follows: * Planning Phase * Risk Analysis Phase * Engineering Phase * Coding and Implementation Phase * Evaluation Phase

The advantage of the spiral model is that it is a realistic model, which is often used in the development of large software. There is a systematic approach used in the spiral model, which is integrated into the iterative framework. This helps in ensuring there is no problems in the software. Since changes to the software can be made at any point of time in the software development process.

In the spiral model, it is important to have a member in the team, who is an expert at risk assessment. Without correct risk assessment, there are chances that the software can utterly be a failure. This may at times become an overhead for the both the client as well as the software development company, affecting the cost of the project.

The first software development methodology will be the Waterfall Model, the second software methodology will be one of your own choosing provided that it is not the Agile Methodology nor the Rational Unified Process (RUP or UP).

For both the software development methodologies do the following:

1. Describe each law in your own words. Illustrate with a practical example.
[4 + 4 = 8 marks] 2. Your first task is to describe each software development methodology clearly and completely in your own words. You may use diagrams, examples or UML to help you do this.
[4 + 4 = 8 marks]

3. Using the above four laws of the text, show where these are either implemented or missing in each software development methodology (Total Two). If a law is missing, explain the consequences and suggest how the process might be improved.
[4 + 4 = 8 marks]

4. For each software development methodology, give an example of a project which it would be well suited for and one which it would be inappropriate for (Total Two projects for each software development methodology). Justify your answers.
[4 + 4 = 8 marks]

Additional Item for ITECH6501

McIlroy’s law
Software reuse reduces cycle time and increases productivity and quality (L15)

5. Describe and illustrate this law with examples. This law was published in 1968; is this law still valid today? Justify your answer with examples.
[4 + 4 = 8 marks]
NOTE: All description should be in your own words. Your report should adhere to the guidelines for the presentation of academic work1. Please review the Plagiarism section in the Course Description.

Please refer to the marking criteria for more detailed breakdown of marks.
Marking Guide
□ ITECH3501 □ ITECH6501

Student Name: ____________________________ ID: ____________________

Describe each law (four laws) Illustrate with a practical example (four examples) | / 4 / 4 | Describe each software development methodology (two methodologies) Use of diagrams, examples or UML | / 4 / 4 | Using the first four laws of the text, show where these are either implemented or missing in each software development methodology. If a law is missing, explain the consequences and suggest how the process might be improved. 1. Waterfall Methodology 2. Any other methodology provided that it not the Agile Methodology or the Rational Unified Process (RUP or UP). | / 4 / 4 | For each software development methodology, give an example of 1. A project which it would be well suited for and 2. One which it would be inappropriate for (Total Two projects for each software development methodology). | / 4 / 4 | Total | /40 | Weight 10% | /10 | Additional item for ITECH6501 | /8 | ITECH6501 Total | /48 | ITECH6501 Weight 10% | /10 | Comments: |
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1 http://www.ballarat.edu.au/current-students/learning-and-study/resources/general-guide-for-the-presentation-of-academic-work