Please read DIC Projects first. This 0README is a supplement to the lectures. It describes a bit of the philosophy behind the course and some details of the source code given to you as a start.

Prerequisites

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++).

How Does It Work?

We will go over this in the lectures.

Compilation + Make

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.

Original v Generated Files

The following are the "original" (i.e., created by a human programmer) files.

Makefile    the makefile for the project
server.x    server rpc interface
server.c    server specific code
client.x    client rpc interface
client.c    client specific code
ed-script   to generate client_s.c from client_svc.c
xwindow.c   a collection of simple X11 procedures
transient.c gets a vacant program number

Details

rpcgen server.x generates server.h server_xdr.c server_clnt.c server_svc.c
rpcgen client.x generates client.h client_xdr.c client_clnt.c client_svc.c
client_s.c is a minor variation of client_svc.c mechanically produced by running an editor script on client_svc.c. We insert startclient(...) just above the svcrun() line.
Just the xwindow.c can be compiled as a stand-alone program xwindow7370 to check for X11 problems.
Note the use of static int i within procedures; such an i is not allocated on the stack. This makes i "stay/live" even after that procedure returns.
Keep the compiler flags -Wall -ansi -pedantic -std=c99 on; read-up on what these do. There should be zero errors/ warnings. The rpcgen generated code unfortunately is not as kosher. Note also that non-Linux OS may have ancient rpcgens that generate even worse code so far as these flags are concerned.
Our code uses alarm, fork, pipe s, and signal s. Our (simple minded) use of signals requires -D_BSD_SIGNALS.
The % make will compile the source code file deregall.c into a program named deregall7370. This can de-register transient RPC processes.
To clean up the project dir, invoke % make clean.
To archive a version, do % make tar

How to Run It

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.

Host names below can be IP addresses (better/ simpler actually). In the OSIS lab, we use private IP addresses 192.168.17.*
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
Run the "server" as a background process on a machine of your choice.\ % server7370 &
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.

Miscellaneous

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
See what libraries are actually in use: % ldd client7370 server7370