CPE 401/601 Computer Network Systems

Spring 2015

Programming Assignment 1: Online Social Network

Due on Thursday, February 26, at 1:00 pm

Online Social Network


In this assignment, we will develop a simple multi-threaded Online Social Network.

The code that you develop in this part will serve as a basis for the following programming assignments. You must create a pair of programs (client and server). The server will act as a central repository where clients will post and access wall posts and exchange messages. All communications happen through the server. Clients establish a TCP session with the server when they become online. Clients also notify the server when they terminate.

The server code should be started with a parameter of port-number. Similarly, client code should be started with parameters of user-ID, server-IP, and server-port (all separated with spaces).

The Server should use threads to handle client connections. Note that, you need to use locks to prevent concurrent writing of common data structures. Moreover, if threading pool is used, 3 bonus points will be added to the grade.

Message Formats

Following are the application level messages sent from/to the server using TCP sockets:

Note that, these formats are recommended (as we will not cross test). You need to implement these functionalities.

Sample XML files

publicProfile.xml content.xml


Report all major actions as the program communicates with other server/users in a file named Activity.log.

We assume user-IDs to be at most 32 characters without any white space characters.

When a malformed message is received report it in a log file named Error.log.

You may utilize localhost ( or actual IP address) to test your program by running multiple users on the same machine but within different folders (with different port numbers).

If testing on multiple machines, be sure that the machines are not behind a NAT (or within the same subnet).

You might get TCP messages in multiple segments even one byte at a time. Hence, you must check whether you have read all the message when parsing them (TCP streams).


You must submit all the source code in Python with sufficient comments to help understand the code.

You must include in your submission a file named Readme.txt that includes your name and a brief description of your submission, including the name of each file submitted along with a one line description of what is in the file.

If your code is not complete, tell us what works and what doesn't in Readme.txt file. If you are submitting code that does not compile, please tell us that as well. If you borrow code from someone else, you are required to tell us about it (this must also be documented in the code itself).

Finally, feel free to include a description of any problems you had or anything else you think might be helpful to us.


You should work individually.

Your project will be tested to make sure it works properly.

Your grade will depend on the functionality and the code quality. Hence, please pay careful attention to clean, modular and extensible design as you implement the project.

There will be bonus grades for extra functionality (such as a well designed GUI) not required by the project (optional and at the discretion of the instructor).

There will be bonus for students that point to major issues or add to program structure.


This document will evolve as we discuss the project and determine communication protocols and messaging formats.

Don't wait till the last minute to start this phase!

Last updated on Feb 13, 2015