Mishaal Aleem
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>> What you have done in the assignment.

In this assignment I have written 4 C++ scripts. The client script
interfaces with the user. It reads the users input file line-by-line and
passes it to the edge server using TCP and the edges static TCP port. The
edge server interfaces with the client. The edge server numbers the lines
and sends them to the back-end servers using UDP and the back-end servers
static UDP ports. The back-end servers do not communicate with each other at
all. They simply receive lines from the edge server, and do the appropriate
bitwise computations. They also format the output string properly. Finally,
they send the computed lines back to the edge server over UDP using the
edge servers static UDP port. The edge server then sends the lines back to
the client using the same TCP connection that the client initially opened.
Finally, the client orders the lines and outputs them to screen for the
user. The servers all stay running so that if the user wants to run another
input file, they can simply call ./client <input_file> again.  


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>> What your code files are and what each one of them does.

client.cpp: Client which reads the input file, breaks it up into lines,
sends the lines to the edge server, receives the computed lines, and
outputs them to the screen
client.h: Client header file

edge.cpp: Edge server which receives lines from the client, appends them
with a number, sends them to the correct back-end server for computation,
receives  the computed lines from the back-end servers, and sends the
computer lines to the client
edge.h: Edge server header file

server_and.cpp:  Back-end server AND, which receives all AND ines, does all
AND computations (shows them on screen), and sends computed lines to edge
server
server_and.h: Back-end server AND header file

server_or.cpp:  Back-end server OR, which receives all OR lines, does all
OR computations (shows them on screen), and sends computed lines to edge
server
server_or.h: Back-end server OR header file

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>> What the TA should do to run your programs.

1. Open 4 terminal windows
2. In each terminal window, navigate to the folder containing all the
program files
3. Run the command "make all" in any of the terminals
4. In one terminal, run the command "make server_and"
5. In another terminal, run the command "make server_or"
6. In another terminal, run the command "make edge"
7. In the last terminal, run the command "./client <input_file>" (replace
<input_file> with the name of the input file)
8. The program will run and the output will show in the 4 terminal windows
9. To run another input file, simply run the command "./client
<input_file>" in the same terminal window as before
10. When you are all done, press "Ctrl+C" in the three server terminal
windows 

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>> The format of all the messages exchanged.

The client reads the input file line-by-line and sends each line as a
message to the edge server. It also sends an "over" message when its done
sending the file lines. 
The edge server appends a 3-digit number to the beginning of the line. So
for example, it appends "000:" to the first line, and "024:" to the 25th
line. 
The edge passes the appended and lines to the back-end and server, and the
appended or lines to the back-end or server along with a final "over"
message.
The back-end servers each write lines of the format "###: <NUM 1> <and/or>
<NUM 2> = <COMPUTATION>" for each line they receive, and send these lines
back the edge server and a final "over" message.
The edge server sends these lines, without modification, to the client and
follows with an "over" message.
The client sorts them and outputs them to the screen, but doesn't output
the first 4 character to screen ("###:"). 

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>> Any idiosyncrasy of your project. What conditions the project fails, if
any.

There are no known cases where the project fails.

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>> Reused Code: Did you use code from anywhere for your project?

I used code from "Beej's Guide to Network Programming" Section 6 in all
parts of my program: client, edge, back-end and, back-end or.
The following functions are derived from "Beej's Guide to Network
Programming":
get_in_addr
sigchld_handler

Other functions, including main() in client, prog() in the servers, use a
few lines based on "Beej's Guide to Network Programming" inside the function.
The blocks or individual lines are all marked with the comment "From Beej" to
signify the code which was from the guide.