Implement the various functions in the different directories.  The
app_{simple/stress}_{client/server}.c are provided to you to test.  
Some functions you have already implemented in previous labs.

BUILDING AND RUNNING:

4 machines are used: bear, green, spruce, gile

Use make to compile. 
To run the application:
1, start the overlay processes:
	At each node, goto overlay directory: run ./overlay&
	The overlay processes on 4 nodes should be started within 1 min.
	wait until you see: waiting connection from network layer on all the nodes.
2. start the network processes: 
	At each node, goto network directory: run ./network&
	wait until you see: waiting for connection from SRT process on all the nodes.
3. start the transport processes and run the application:
	AT one node, goto server dicrectory: run ./app_simple_app or ./app_stress_app
	At another node, goto client directory: run ./app_simple_app or ./app_stress_app

To stop the program:
use kill -s 2 processID to kill the network processes and overlay processes

If the port numbers used by the program are used already, the program exits.