9.5. Programming Assignment 5 – Add BRB feature to Multi-threaded Chat Server

In the previous section (A Multi-threaded Chat Server), we review the strategies for writing asynchronous and threaded servers. In particular, we apply those strategies toward developing a multi-threaded chat server.

I am providing to you a working chat server and client program complete with a graphical user interface. The client program uses wxPython [wxPython] to implement the graphics, which was also used in the web programming project. You should not need to modify the client program at all.

The application layer protocol used by the chat application is similar to IRC. For example, the user of the client program might send /nick newName to change the name attributed to their messages. Also messages /quit or /quit parting message may be used to announce their departure and close the connection. The functions string.replace() and string.strip() from the string module are used to help with the needed string processing.

You are to modify the chat server to implement a be right back (BRB) feature. You will notice a Be Right Back button in the graphical client application. When that button is clicked on, a message is sent to the server of the form: /brb message, where message is text taken from the user input window, if any is available. After the BRB button is clicked on, the text of button changes to I’m Back. Similarly, when the button is clicked on a second time, a message of /back message is sent to the server.

The behavior of the server should be to announce when the user is away and back again to all the users. While the user is away from the chat session, no messages should be sent to the user. After they are back, any messages still in the queue, which have not previously been sent to the user should be sent at that time.

You can find example code to model your code after in the existing handling of /nick and /quit.

This is actually a fairly short programming assignment in terms of how much code you need to add to the program. The main goal is that in going through the program, you gain an understanding of how sever programs work. To supplement the programming assignment and to facilitate your comprehension of the program, you will also find below some reflective questions to answer and submit as the second part of homework covering server programming.

9.5.1. Files to Download

The first three files below are all needed for the client part of the chat application.