3.1.11 Software Development Life Cycle

Question 1

what are the 5 steps of the SDLF?

Answer 1

1. specification requirements/ analysis
2. design
3. implementation
4. testing
5. evolution/ maintenance

Question 2

what happens during the specification requirements/ analysis stage?

Answer 2

the programmers, designers and the clients discuss the needs of the user so it is clear what is required

Question 3

what happens during the design stage?

Answer 3

the solution is planned, using the specification discussed in the previous section

Question 4

what happens during the implementation stage?

Answer 4

the designs are turned in code

Question 5

what happens during the testing stage?

Answer 5

written code is tested against the specification to ensure the code provides a solution to the problem

Question 6

what happens during the evolution/ maintenance stage?

Answer 6

changes/upgrade that the software goes through after it is delivered to the client

Question 7

advantages of the cyclical model {4}

Answer 7

• Clear defined stages.
• Simple to understand and use.
• Well understood stages.
• Easy to arrange tasks.

Question 8

disadvantages of the cyclical model {4}

Answer 8

• It’s difficult to measure progress within stages.
• Cannot accommodate changing requirements.
• No working software is produced until late in the cycle
• Risk and uncertainty is high

Question 9

what is the waterfall model?

Answer 9

each phase must be completed before the next phase can begin

Question 10

advantages of the waterfall model {4}

Answer 10

• Simple and easy to use.
• Easy to manage due to the rigidity of the model
• Phases are processed and completed one at a time.
• Works well for smaller projects where requirements are very well understood.

Question 11

disadvantages of the waterfall model {6}

Answer 11

• Lack of flexibility
• No working software is produced until late during the life cycle.
• High amounts of risk and uncertainty.
• Poor model for complex, object-oriented and long projects.
• Can be difficult to go back a step if needed.
• Poor model where requirements are at a high risk of changing.

Question 12

what is the spiral model?

Answer 12

four phases: Planning, Risk Analysis, Engineering and Evaluation.
The software project repeatedly passes through these phases in iterations

Question 13

advantages of the spiral model {5}

Answer 13

• High amount of risk analysis
• Good for large and mission-critical projects.
• Software is produced early in the software life cycle.
• More client consultation
• Ability to return and fix problems.

Question 14

disadvantages of the spiral model {4}

Answer 14

• Can be a costly model to use.
• Risk analysis requires highly specific expertise.
• Project’s success is highly dependent on the risk analysis phase.
• Doesn’t work well for smaller projects.

Question 15

what is the incremental model?

Answer 15

more than one development cycle occurs at a time, which are divided up into smaller, more easily managed iterations that passes through all the stages except maintenance (i.e requirements, design, implementation, testing)

Question 16

advantages of the incremental model {4}

Answer 16

• Generates working software quickly and early during the software life cycle.
• More flexible – less costly to change scope and requirements.
• It is easier to test and debug during a smaller iteration.
• Easier to manage risk because risky pieces are identified and handled during it’d iteration.

Question 17

disadvantages of the incremental model {4}

Answer 17

• Needs good planning and design.
• Each phase of iteration is rigid and doesn’t overlap any other
• Needs a clear and complete definition of the whole system before it can be broken down and built incrementally.
• Total cost is higher than waterfall.

Question 18

what is the v-shaped model?

Answer 18

Each phase must be completed before the next phase begins. Testing of the product is planned in parallel with a corresponding phase of development.

Question 19

what does the angular component and radius of a spiral model represent?

Answer 19

angular component represents progress

radius represents cost

Question 20

advantages of the v-shaped model {4}

Answer 20

• Simple and easy to use.
• Testing activities like planning, test designing happens well before coding. This saves a lot of time so a higher chance of success over the waterfall model.
• Defects are found at an early stage.
• Works well for small projects where requirements are easily understood.

Question 21

disadvantages of the v-shaped model {4}

Answer 21

• Very rigid
• Software is developed during the implementation phase, so no early prototypes of the software are produced.
• little flexibility so adjusting scope is difficult and expensive
• doesn’t provide a clear path for problems found during the testing phase

Question 22

what does the v-shaped model look like?

Answer 22

specification———review/test——–operational
requirements testing
\ /
high lvl design—-review/test—–integration
\ testing
detailed spec—— test——unit testing
\ /
implementation