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Software Engineering

Ian Sommerville

Chapter 21

Software evolution - all with Video Answers

Educators

Chapter Questions

02:19

Problem 1

Explain why a software system that is used in a real-world environment must change or
become progressively less useful.

Akash M
Akash M
Numerade Educator
03:16

Problem 2

Explain the rationale underlying Lehman’s laws. Under what circumstances might the laws
break down?

Pronoy Sinha
Pronoy Sinha
Numerade Educator
01:31

Problem 3

Briefly describe the three types of software maintenance. Why is it sometimes difficult to
distinguish between them?

Hubert Agamasu
Hubert Agamasu
Numerade Educator
00:47

Problem 4

As a software project manager in a company that specialises in the development of software
for the offshore oil industry, you have been given the task of discovering the factors that
affect the maintainability of the systems developed by your company. Suggest how you might
set up a programme to analyse the maintenance process and discover appropriate
maintainability metrics for your company.

Jennifer Stoner
Jennifer Stoner
Numerade Educator
01:50

Problem 5

From Figure 21.7, you can see that impact analysis is an important sub-process in the
software evolution process. Using a diagram, suggest what activities might be involved in
change impact analysis.

Emily Himsel
Emily Himsel
Numerade Educator
01:25

Problem 6

What are the principal factors that affect the costs of system re-engineering?

Manik Pulyani
Manik Pulyani
Numerade Educator
02:20

Problem 7

What are the essential conditions for software re-engineering to be successful?

Arul Sharma
Arul Sharma
Numerade Educator
03:16

Problem 8

Under what circumstances might an organisation decide to scrap a system when the system
assessment suggests that it is of high quality and high business value.

Jennifer Stoner
Jennifer Stoner
Numerade Educator
04:19

Problem 9

What are the strategic options for legacy system evolution? When would you normally replace
all or part of a system rather than continue maintenance of the software (with or without reengineering)?

Akash M
Akash M
Numerade Educator
02:22

Problem 10

Explain why problems with support software might mean that an organisation has to replace
its legacy systems.

Rashmi Sinha
Rashmi Sinha
Numerade Educator
01:35

Problem 11

Do software engineers have a professional responsibility to produce code that can be readily
evolved even if this is not explicitly requested by their employer?

Rashmi Sinha
Rashmi Sinha
Numerade Educator
03:16

Problem 12

The management of an organisation has asked you to carry out a system assessment and
suggested that they would like the results of that assessment to show that the system is
obsolete and that it should be replaced by a new system. This will mean that a number of
system maintainers will lose their jobs. Your assessment actually shows that the system is
well maintained and is of high quality and high business value. How would you report these
results to the management of the organisation?

Jennifer Stoner
Jennifer Stoner
Numerade Educator