CS475: Computer Networks - Socket Programming

Activity Goals

The goals of this activity are:
  1. To implement a multithreaded, multiplexed socket I/O application that implements an application layer protocol

The Activity

Directions

Consider the activity models and answer the questions provided. First reflect on these questions on your own briefly, before discussing and comparing your thoughts with your group. Appoint one member of your group to discuss your findings with the class, and the rest of the group should help that member prepare their response. Answer each question individually from the activity, and compare with your group to prepare for our whole-class discussion. After class, think about the questions in the reflective prompt and respond to those individually in your notebook. Report out on areas of disagreement or items for which you and your group identified alternative approaches. Write down and report out questions you encountered along the way for group discussion.

Model 1: TCP Socket Programming

Socket Programming Tutorial
Threaded Socket Programming Example

Questions

  1. Create a socket to connect to your favorite web server and make an HTTP request, printing its response to the screen.
  2. What port number does your server socket use, and what port should your client use to connect?
  3. How do we free up the primary server socket port for subsequent connections, so that they can be handled simultaneously?

Embedded Code Environment

You can try out some code examples in this embedded development environment! To share this with someone else, first have one member of your group make a small change to the file, then click "Open in Repl.it". Log into your Repl.it account (or create one if needed), and click the "Share" button at the top right. Note that some embedded Repl.it projects have multiple source files; you can see those by clicking the file icon on the left navigation bar of the embedded code frame. Share the link that opens up with your group members. Remember only to do this for partner/group activities!

Model 2: Multithreaded TCP Socket Programming


Questions

  1. What is different about this example? What can it do that the prior example cannot?
  2. Suppose you have multiple concurrent chat connections, but only one System.in standard input stream. How might you determine which socket should send each line that the user types in?

Model 3: TCP Socket Programming with Python


Questions

  1. Do you think this program would work with the Java socket programs? Why or why not?

Model 4: UDP Socket Programming

Questions

  1. Describe, in your own words, the behavior of the client and the server in this example.
  2. How does a UDP socket program differ from a TCP socket program, in terms of its design and behavior?

Submission

I encourage you to submit your answers to the questions (and ask your own questions!) using the Class Activity Questions discussion board. You may also respond to questions or comments made by others, or ask follow-up questions there. Answer any reflective prompt questions in the Reflective Journal section of your OneNote Classroom personal section. You can find the link to the class notebook on the syllabus.