Development Methodologies and Analysis

Learning Intentions

Identify and explain different development methodologies
Understand the term purpose and what functional requirements are

Success Criteria

I can identify and describe different development methodologies
I can identify functional requirements of a piece of software from its purpose

Computational thinking

Computational thinking is a way of thinking about a problem in such a way that makes it solvable by a computer system.
We write computer programs as a sequence of instructions called an algorithm.
There are several different steps to programming and these steps are often called the Waterfall Model.

The Waterfall Model

The Waterfall Model is a traditional way of developing software:

Analysis

Design

Dance

Implementation

Testing

The

Documentation

Dark

Evaluation

Every

Maintenance

Monday

Stage

Word

bUT WHY IS IT CALLED THE WATERFALL MODEL?

The Waterfall Model is a traditional way of developing software:

bUT WHY IS IT CALLED THE WATERFALL MODEL?

The reason we call it the Waterfall Model is that it goes from one stage to the next (cascading like a waterfall). But it's not the best name because each stage within the model has to be revisited over and over again. Unlike a waterfall, you can go back up the waterfall over and over again.
For example, testing comes after implementation, but what if there is a bug discovered when testing? Do we just proceed to the documentation stage or do we go back and try to fix the code?
The Waterfall Model is called an iterative model because of the fact that steps can be revisited over and over again.

The waterfall model

Notice that at each stage there are arrows going both forward and backwards

National 5

For National 5, we study the following areas in particular:
- Analysis
- Design
- Implementation
- Testing
- Evaluation
It should be noted however, that the Documentation stage is involved in every step of the process.

Development methodologies

There are other development methodologies such as agile development and Rapid Application Development (RAD).

Development methodologies: Agile

Agile development is a different method altogether, in which the client is involved at all stages and there is a lot of client involvement in which the client will test the product over and over as new features are added.
Each development cycle is called a sprint.
Agile development does however, have issues. The main issue is that documentation is scarce and often very minimal. It also can lead to the client constantly changing their requirements and being stuck in a perpetual development cycle.

Development methodologies: RAD

Rapid Application Development a provides another model of development.
It differs from both the Waterfall Model and agile development in that prototypes are created early on and the client can test the prototypes and ensure they are happy with it.
RAD is only suitable for smaller projects as it gets difficult to manage.
The concept behind RAD is that the time needed to build the software should be minimal.

Past Paper Questions

The software development process is described as iterative.

Explain why it may be necessary to return to the design stage.

1 mark

Explain why the development of software is called an iterative process

1 mark

Answer the questions on page 5 of the National 5 Computing Science book

Task

Analysis

Analysis is the first stage of the Waterfall Model.
The Analysis stage involves several meetings between the client and the developer.
During these meetings, the client will explain what they would like in the finished product, how they would like it and the developer will explain what can be done (if at all possible)
A document called the software specification is created and signed by both parties.

Analysis

Purpose of software is what the software should do.
This is agreed in the software specification by both the client and the developer.
Further to this, the developer will come up with the functional requirements for the software. These are things that the software must be able to do. The functional requirements should also outline and detail the inputs, processes and outputs of the program.

Answer the questions on page 5 of the National 5 Computing Science book

Task

Past Paper Questions

A program is being designed that will allow pupils to add money to their lunch money account. The user enters their name, an 8 character password and the amount of money they want to add. A button is then clicked and the updated
balance of the account is displayed.

Analyse the problem and identify all inputs, processes and outputs.

3 marks

Past Paper Questions

In a flight booking app, users are asked to enter their departure airport, destination airport, departure date, return date, number of adults and number of children.

A message will then be displayed showing the total flight cost and the duration of
the trip.

Describe two processes for the flight booking app.

2 marks