|
(a)The
process of performance evaluation begins with an inventory:information
is
obtained about the design and specification of the existing system.List
and explain the other important steps and activities in the process.[5
marks ]
The process of
performance evaluation (after inventory )
•measurement :measure performance of existing system on its own
terms;
examine inputs and outputs
•modeling :construct causal or simulation model of system ,to
be used for
explaining and testing alternative configurations
•validation of model :assess accuracy of model,whether it accurately
predicts and explains behaviour of existing syste ;adapt if necessary
•change the model :that is,model the intended change in the system
and predict effects
•change the system :modifying the system itself,and observing
the results
In each case, award 1 mark, but only if the explanation is clear and
appropriate. The answers do not have to be divided into these five
parts; it is the information about activities that is most important.
[5 marks ]
(b)Software does not degrade in the way
that hardware does;it is not subject to physical wear and tear.So
why is software aintenance necessary?Give two possible reasons.[2
marks ]
Why is software maintenance necessary?
•because of changing needs or requirements
•because of changing environments
•because errors may be detected that demand correction
any two correct reasons, 1 mark each [2 marks ]
(c)Suppose that your company produces
a software package for stock control and
customer accounts in video rental stores.Explain,with the aid of examples,what
is
meant by the following types of maintenance :
(i)corrective maintenance
(ii)adaptive maintenance
(iii)perfective maintenance
(iv)preventative maintenance
In each case,explain the eaning of the term,and then give an example
of how and
why that type of maintenance might be carried out on your company
’s software
package.[8 marks ]
•corrective maintenance :correcting errors and problems once
they have occurred (1 mark);problems might be detected in the operation
of the system (1 mark)
•adaptive maintenance :changing system in response to changes
in requirements or methods (1 mark); system might need to be adapted
to deal with DVD rentals (1 mark)1 mark
•perfective maintenance : changing a working system to improve
performance or efficiency (1 mark); system is too slow in operation
(1 mark)
•preventative maintenance :inspection and review of the system
to detect errors or anticipate potential problems (1 ark); system
should be checked to make sure that customer data is being properly
recorded (1 mark)
in each case, one mark for the explanation, and one mark for any sensible
example—no example, no second mark [8 marks ]
|