Homework 11

22C:116, Fall 2001

Due Friday Dec 7, 2001, in class

Always, on every assignment, please write your name legibly as it appears on your University ID and on the class list!

1. Problems from Text:
   problem 12 on page 579
   problem 22 on page 580
   problem 22 on page 580
   problem 8 on page 667
   problem 19 on page 668
   problem 25 on page 669

2. Problem: Consider the following steganographic coding technique, used to apply watermarks to source code: Many lines in many source programs are indented. All indents of 8 or more spaces can be done using tabs. Therefore, when a line begins with up to 7 spaces and a tab, or with 8 spaces and no tab, it is indistinguishable, in print or on the screen, from a line beginning with just a tab. How many bits of the watermark can be encoded in each tab-indented source line?

3. Problem: Consider a fault tolerant system based on the Amoeba or Demos model, where each application has capabilities allowing it to communicate with other applications under the kernel. When one of the servers fails, it is essential to allow the replacement server to somehow take over for the server that failed. This is not a process migration problem, formally speaking, yet it has many aspects that are similar to the process migration problem. What mechanisms required for process migration are applicable to this problem, and how are they used to solve the problem.