General Assignment guidelines

• Changes will be highlighted in green
• Important notices will be highlighted in yellow
• Assignments have to be strictly submitted according to guidelines. (will be put up later)
• Assignments can be done in groups of two. lone wolves will be given some extra credit.

Assignment on Interprocess Communication

Application

• Simulate journey of n cars traveling from Delhi to Agra.
• Assume that cars do not need to co-ordinate with each other (ignore collision).
• Speeds of each car should vary as a pseudo random process: i.e. 1 sec period the car will move forward a distance d(i) where d(i) is average_speed +- random_noise to take into account potholes in the way.
• There are 5 filling stations/rest areas along the way. A car will randomly choose to stop at a filling station/rest area and stop for a random amount of time (but at least 10 seconds) and no more than 3 minutes. The cars start with different capacities of fuel tank. Ensure that the cars will definitely stop at a filling station if they don’t have enough fuel to reach the next filling station. Again you can choose how much fuel you take on at a station.
• Display the positions, average speed and fuel status at the current position of the cars.
• On keyboard input you should be able to reposition the cars.
• At the end, report the time in which the cars have completed the journey

Implementation

Framework of the program

• There will be two types of processes. Use fork() to create these processes.
  • Control process : One control process should be able to communicate with the car processes. It will display the position and fuel status of the cars. It should be able to accept keyboard input and should be able to reposition the cars.
  • Car process : There will be n number of processes for cars. They will maintain speed, position, fuel status of the car and any other car specific variables.
• InterProcess communication : Implement using each of the following IPC primitives
  • Pipes
  • FIFO files
  • Message Passing
  • pthreads (the pthread package is not required to be downloaded. It is built in to glibc). Note in case of pthreads you will not use the fork
• Programming Style:
  • You should organize your code so that things are modular. You should separate out declarations/prototypes into header files.
  • You should make separate files for, the display/keyboard routines, the car and control processes and one file each for each of the possible IPC choices.
  • Use a makefile to define how to make each of the possible targets (carrace_pipes, carrace_fifo, carrace_mpc and carrace_pthreads) by suitable compilation, linking and preprocessor directives.
  • When programming application with different types of IPC (pipes, FIFO files and message passing) only file for interprocess communication routines should change. Other files should remain same. i.e. during compilation of different applications, different IPC files should be used. (define appropriate wrapper procedures so your main code need not change. You can use the #ifdef preprocessor directive to selectively compile the relevant code.)
  • There should be no warnings at the time of compilation.
  • Use ncurses to show different cars in different colours
• Background Reading
  1. Man pages for signal, alarm, umask, sigprocmask, gettimeofday, wait, execve, fork, pipe, open, ipc, clone, msgctl, msgsnd, msgrcv, rand, srand48
  2. Unix Network Programming by W. Richard Stevens
  3. The Linux Programmer's Guide
  4. linux pthreads tutorial. Do not download the package for pthreads. It is built in to glibc.
  5. ncurses for the display.( http://en.tldp.org/HOWTO/NCURSES-Programming-HOWTO/, http://web.cs.mun.ca/~rod/ncurses/ncurses.html )
  6. man pages for make to learn how to prepare a Makefile. 

You have to code using the framework of the files provided below.

.c .h files and a sample Makefile are now available.

Download

Last date for submission:

Submission with the pipes IPC primitive: Aug, 17 2003