A White Board Project using ONR RPC

This course expects that you are already comfortable in the use of networked machines based on Linux/Unix and X11. Learn to login to remote machines via ssh without having to interactively type your password each time; read 2350/ NetworkLab #ssh

Students whose Linux OS programming skills are rusty should study examples for {alarm, fork, pipes, signals, bash scripting} much simpler than what you see in our project files. At WSU, we expect CEG 4350/6350 OS Internals and Design to have taught these. Recommended book: W. Richard Stevens and Stephen A. Rago, Advanced Programming in the Unix Environment, Addison-Wesley, ISBN: 0-201-56317-7. http://www.apuebook.com/

Some of you worry this is C and not C++. C is a subset of C++. Also, the code does use lower-than-what-is-typical-in-C++ libraries. One of the goals of this course: Expose you to the basics of systems programming relevant to distributed computing. If you know C++ well enough, you should be able to fully understand C. Some quick equiv C v C++: malloc/free v new/delete mem allocation; static v private scope; static v static life time; e1? e2 : e3 v e1? e2 : e3 conditional expression;

RPC background is not expected. Several of the RPC lib procedures will be discussed in class. On Linux, these have become part of C std lib; on other OS you may have to explicitly give -lrpcsvc to the linker (ld of gcc or g++).

We will go over this in the lectures.

Expand the tar ball of source code 7370-WB-C-RPC-2014.tbz using tar xvvfj 7370-WB-C-RPC-2014.tbz

It is expected that you will study the source code closely. It is only 800+ lines. You should become so familiar with it as if you wrote it. The only exception is xwindow.c; just read the comments.

The source code as given is ready to be built using make. There should be no compilation/link warnings except possibly in rpcgen-erated code. It should also run without any glitches. If these are not working out (i) in the OSIS Lab, report problems to me, (ii) on Linux systems elsewhere, I may be able to help, but there is too much ground to cover. Below % is my bash prompt as a non-root user.

Some of you may wish to use your own Linux boxes for 7370 work. But Linux installations out-of-the-box are typically not "open" enough for us. Check your Linux Setup first.

1. Host names below can be IP addresses (better/ simpler actually). In the OSIS lab, we use private IP addresses 192.168.17.*
2. In the source code as given: The server is one process running on host H1. The client consists of two processes both running on host H2. It is ok, but not desirable that H1 == H2. H2 is where the X11 server is also running, using the bash-equaivalent of export DISPLAY=H2:0.0
3. Run the "server" as a background process on a machine of your choice.
   % server7370 &
4. Run the "client" from one or more machines of your choice. The client needs four arguments:
   % client7370 <srv-mchn-nm> <wb-nm> <wb-disp> <color>
<srv-mchn-nm> is the name of the machine running your server; <wb-nm> is the name of the whiteboard you wish to create/join; <wb-disp> is the name of the machine you are logged in for the X11 display; <color> is a 6-hex-digit X11 RGB color number for lines of this client;

Here are a few bash procedures: A simple "smoke test" with all the processes running on localhost and kill all and deregister 7370 related processes. Read man killall and man pkill.

smokeTest7370() {
  ./server7370 &
  echo -n Server started, press Return to continue; read
  ./client7370 localhost b0 localhost ff0000 & # RGB=ff0000 = red
  echo -n client started, press Return to continue; read
  ./client7370 localhost b0 localhost ff00 & # RGB=00ff00 = green
  echo -n client started; press Return to continue; read
  ./client7370 localhost b0 localhost ff & # RGB=0000ff = blue
  echo -n client started, press Return to continue; read
  rpcinfo -p
}

killall7370() {
  killall -q server7370 client7370
  ./deregall7370 536871065  # change this to your server num
  ./deregall7370
  rpcinfo -p
}

freshStart7370() {
  killall7370
  smokeTest7370
  ps
  rpcinfo -p
}

Locate where rpcinfo is. Perhaps it is in /usr/sbin instead of /usr/bin. Read its man page. Here is an example invocation on Linux machines:

% rpcinfo -p
   program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    ... more lines

Do the above after a fresh reboot. This shows the presence of other standard RPC processes. After you "close" your WB project demo, the list then should be the same.

1. Learn to use backtrace(); it will offset the time you may otherwise waste in debugging. http://www.gnu.org/software/libc/manual/html_node/Backtraces.html
2. See what libraries are actually in use: % ldd client7370 server7370