Question 8

Question 1

What is the probable content of this exam question?

Answer 1

(1) Discuss components and services.

(2) Specify usability or performance scenarios.

Question 2

Suggest 4 advantages of developing software by plugging together off-the-shelf components.

Answer 2

(1) Should be cheaper.
(2) Allows quicker development.
(3) Behaviour of well-tried components will be well understood.
(4) Components are replaceable with other components that have the same interface.

Question 3

Suggest 4 disadvantages of developing software by plugging together off-the-shelf components.

Answer 3

(1) We will be restricted to the capabilities of the components.
(2) Some additional software is likely to be needed.
(3) Adapters may be needed if interfaces are incomplete.
(4) Creating a system from pluggable components may be more difficult that it sounds.

Question 4

What is the difference between a provided and a required interface?

Answer 4

A provided interface describes the operations a component provides to other interfaces.

A required interface describes the operations a component requires from other components.

Question 5

What are the usual response measures for a performance scenario?

Answer 5

(1) Latency.
(2) Deadline.
(3) Throughput.
(4) Jitter.
(5) Miss rate.
(6) Data loss.

Question 6

Given the usual response measures for a performance scenario, choose 3 that would be most appropriate in the case of an internet radio service, and briefly explain your answer.

Answer 6

(1) Latency will affect hoe quickly a channel can start playing.
(2) Throughput must be sufficient to stream the service to the user.
(3) Data loss must be low otherwise some part of the broadcast will be missed.