Exercise 3
        ==========

1. The assignment:

Using Spread, you should write a tool that reliably multicasts 
messages between n processes that reside on the same Spread network. 

The tool consists of only one program: 
	mcast - the tool's process. 

The mcast process should be run as follows:

mcast <num_of_messages> <process_index> <num_of_processes>

The num_of_processes indicates how many mcast processes will be run. 
The maximal number of num_of_processes is 10.

The num_of_messages indicates how many messages THIS mcast has to
initiate.  This number might be on the order of 50000.  Each message
should contain the creating process_index, the message_index, and a
random number, each of which is stored in a 4 bytes integer.
Therefore, each message should contain 12 bytes at least.  The
message_index is a per-process counter that is incremented each time 
a process initiates a message.

The requirement is for all of the processes to deliver all of the 
messages in AGREED order.

On delivery of a message the mcast should write to a file, 
in ASCII format, the packet id as follows:
   fprintf( fd, "%5d, %6d, %6d\n", 
	message->process_index, message->message_index, 
	message->random_data );

The output file name will be <process_index>.out

After all the mcast processes have been run, they get membership
messages and wait until all of them are running (thus, there is no
need for a separate start program).

To benchmark your program you should run a test with 8 machines where 
only 5 of them send 20000 packets each, for a total of 100000 packets,
and time how long the test takes. The other machines will get 0 as 
<num_of_packets>.  

Spread will already be running on the ugrad machines on its default
port, 4803.  

2. A final submission of documentation, writeup and code. Due 
Thursday,  March 27 at 11pm. This is an electronic submission. 
See instructions below.

This final report should also include a brief discussion of the
performance results you achieved. 
The programs should be complete, sound, and well-documented.

A makefile that compiles and builds your program with clearly
documented options (if needed) is required.

You should make a tar file named exactly as your login account with
all your documents and code (DO NOT include core files or object files)
and email the tar file as an attachment to cs437@cs.jhu.edu. The
subject of the email should be "Exercise 3 submission <account name>",
and in the body of the email write the names of the students that
worked on the exercise.

Please bring a printed version of the your submission to class Monday
March 31.