Design Processes

Question 1

Pros (3) and Cons (4) of the Waterfall Method

Answer 1

+ Reflects standard engineering practice
+ Encourages breakdown of complex systems
+ Good for management of documentation

• Inflexible
• Needs an early commitment to requirements
• Late changes increase the costs
• Too slow

Question 2

Describe: Rapid Prototyping

Answer 2

Used when requirements are vague to help customer decide what they want.
- Easy to demonstrate and collect feedback

Prototype is then discarded to build the real system

Question 3

Describe: Evolutionary Prototyping

Answer 3

Use if requirements are vague and where time constraints on project may force early termination.

Prototype becomes the final product

Question 4

Pros (3) and Cons (3) of Prototyping

Answer 4

+ Helpful when requirements are vague
+ Flexible
+ Accomodates late changes

• Development process isn’t visible
• Poor structure can emerge
• Can’t manage large scale systems that would require any coordination between parties

Question 5

Describe: Spiral Lifecycle Model (4 stages)

Answer 5

Aim is to control risks through the project: the key idea is to evaluate the risks and reduce them.
Can terminate features at each evaluation.

4 Stages: - set objectives for current stage

                - evaluate risks
                - develop &validate current stage
                - plan next stage

Question 6

Pros (2) and Cons (1) of Spiral Lifecycle Model

Answer 6

+ adapts to fit projects
+clear process and evaluation

• late changes can have serious consequences

Question 7

When is Formal Systems Development useful?

Answer 7

For safety critical systems

Requires formal specification & proof

Question 8

Pros (2) and Cons (3) of Formal Systems Development

Answer 8

+ precise and error free
+ proof of specification

• Precieved as difficult
• Requires mathematical expertise
• Still requires validation

Question 9

Describe Incremental Development.

When is it useful?

Answer 9

Useful if time-to-market is critical
Prioritise requirements (list requirements in order of priority), each requirement is delivered as an increment

Question 10

Describe ‘Shift to Components’ Development? 3 phases

Answer 10

Requirements phase: analyse requirements so they can be mapped onto software components

Construction Phase: Build system from existing components and develop new components to integrate to an existing framework

Reuse & Maintain

Question 11

Pros (3) and Cons (3) of using Components to develop software?

Answer 11

+ Rapid development strategy
+ Encourages code reuse
+ Reducs costs and risks

• High initial set-up cost
• Can lose control of component set
• Sometimes components can be forced to fit a framework

Question 12

Describe the Fountain Lifecycle. How is it: incremental, iterative, parallel?

Answer 12

Incremental:

• develop and deliver on task at a time
• use a prototype system

Iterative:

• revisit any faulty tasks
• revisit any tasks where a change is requested

Parallel:

• Tasks are developed independently
  
  • this gives scope for multi-team development

Question 13

Describe Agile Methods of software development

Answer 13

• No big up front design
• Short increments with daily builds, passing all tests
• Pair Programming
• Anyone can modify the code base

Question 14

Pros (3) and Cons (3) of Agile Development Methods

Answer 14

+Avoids unproductive and wasteful documentation
+ Code is constantly up-to-date
+ Emphasis on testing

• Inflexible process
• Assumes good design will emerge by evolution
• Doesn’t work for large scale projects that require coordination