CS686 - Dependable Computing
ASSIGNMENT 1
Due: February 5
Please type the Reading and Individual Activity parts of the assignment single spaced, 12pt type
with 1” margins, and indented paragraphs with no space between paragraphs. Be sure to include a
face page with course number and course name, assignment number, date, and your name.
For the project part, follow the project document guidelines.
The numbers after each question are the points allocated to that question.
Reading
Read papers 1, 2, and 3 on the class Web site. For papers 1 and 2, prepare a half-page summary.
Turn in your summaries. (20)
Individual Activity
1. The Ariane V software was written in Ada, and the semantics of Ada exception handling were
a factor in the failure. Acquire a copy of the Ada Language Reference manual and read about
the semantics of exception handling in Ada. Write a simple Ada program to illustrate exception
propagation in Ada and describe what happens to your program when an exception is raised.
The exact syntax is not important and there is no need to run the program. (20)
2. Define examples of useful systems that could be considered: (a) safe but neither highly reliable
nor highly available; (b) highly available but not highly reliable; and (c) highly reliable but
not safe. (20)
3. Carefully and precisely, state the dependability requirements for an automobile’s anti-lock
braking system. Carefully consider the issues noted in class. (20)
4. Assuming that Google is prepared to accept no more that a cumulative downtime of 100 min-
utes per year, carefully and precisely state this requirement in a form that will meet Google’s
intent. (20)
5. Make a list of the consequences of failure of a large-area, multi-player game such as Final Fan-
tasy. Separately, consider the effects of: (a) a defect in the graphics system that affects the
appearance of game elements; (b) a defect in the client code that causes a user’s computer to
crash; (c) a server defect that causes loss of game state for large numbers of players; (d) a net-
work defect that causes game availability to be limited in the U.S. on several weekday eve-
nings. (20)
Group Project
Complete this part of the assignment as a group. Turn in just one document for each question from
the group. All group members will receive the same grade.
1. Develop a functional requirements statement for your project. (20)
2. Develop a dependability requirements statement for your project. (20)