Software Engineering, Exam, December 11, 2002.

• Start by reading all the questions, to see if anything is unclear. I plan to visit around 10:30 to clarify questions.
  

• Answers may be written in Swedish or English, or any reasonable mixture of those.
  Dictionaries may be used.

• Start each answer on a new page. Please hand in the pages in the correct order.

• For each question, I give its points and a maximal length of the answer. The optimal length is usually around half of this maximum. (This does not include drawings.)

• A checklist of common mistakes that cost points:
  • Answer all 11 questions. A bad answer never gives less points than no answer.
  • Read the question again after you have written the answer. Verify that you have actually answered the question. Verify that you answered all parts. Verify that you have not hidden the answer between many other irrelevant comments about the topic.
  • In particular, don't forget to give an example if that is requested, and make it a concrete one.
  • Avoid unclear or missing argumentation; risky words are 'of course', 'self-evident', 'better', 'wrong', ...
  • When a question asks you to compare two things A and B, make sure to highlight the contrasts: their differences. I do not want a full description of A and a full description of B, leaving it to me to find the differences.

• Good luck!

1. Given a fixed budget, explain the benefits of incremental development on
   1. usability
   2. functionality
   3. presence of faults
   (3 points, 1 page)

2. Some software is made for a single customer, while other software is developed to be sold on an open market. Explain the resulting differences in the requirements elicitation phase.
   (4 points, 1 page)

3. Explain why a software designer could be interested in tracing a requirement back to its stakeholder(s).
   (3 points, 1 page)

4. A logical three-tier architecture is to be implemented. What kind of requirements influence the choice between a physical three-tier architecture and a client-server architecture with a thin client?
   (5 points, 2 pages)

5. Sometimes the safety of a system requires its availability. Sometimes safety and availability are conflicting requirements.
   1. Give an example of each case.
      (2 points, 1 page)
   2. Point out the crucial difference between the two cases.
      (2 points, 2 lines)

6. Discuss the concept of N-version programming. What is the idea behind it? What are the problems?
   (4 points, 1 page)

7. Consider the following program that given i, computes n, the square of i.

   if i < 0 then i := -i;
   n := 0                                endif;
   while i > 0 do
      i := i-1;
      n := n + 2*i + 1
   endwhile

   1. Give a set of test data (values for i) that constitute a branch coverage test. Show clearly what steps you take to arrive at these values.
      (4 points, 1 page)
   2. Using this program as an example, explain the concept infeasible path.
      (2 points, 0.5 page)
   3. Is the potential error in this program most likely to be discovered by inspection, by a branch coverage test, or by a black box test? Why?
      (3 points, 0.5 page)

8. What are the advantages and disadvantages of using statistical testing with the purpose of finding faults?
   (4 points, 1 page)

9. Discuss the advantages and risks of algorithmic cost modelling (such as the COCOMO model).
   (4 points, 1 page)

10. Describe the relation between software metrics and external quality attributes.
    (4 points, 1 page)

11. Many of the articles argue in favour of creating software in a more orderly fashion than today's practice.
    1. Why do all the "more orderly" techniques move work from the later stages of a project to the earlier stages?
    2. What can be the problems of shifting the work balance in this way?
    (6 points, 2 pages)