Class 2 - The Internet and the World Wide Web

Welcome to the second day of the class!

Today you'll need to watch a video about the course.

You'll need to do the reflection portion again as you did for the previous class reflection. Remember to include details about that lecture for that particular day and make sure to relate it to your own experience

Also, please conduct some research to find out the differences between the internet and the World Wide Web, and post your findings in the appropriate assignment heading.

Course Material

Objectives

From going through this material you should be able to understand:

• What is the difference between the internet and the world wide web?
• How the OSI Model is used to understand how computers communicate
• How TCP/IP relates to the OSI Model
• How we come to understand the idea of the World Wide Web

What is the difference between the internet and the world wide web?

These two terms are not the same. While there are more formal definitions out there, the goal of what I write out on these pages is to give you a casual reference. Taking a casual approach is partly why I wanted to give write this out for you all.

I want you to think of the internet as the collection of computers around the world (and in space) that are able to communicate with each other. The way these systems communicate, what to communicate and how has to be formalized/standardized into protocols. A popular analogy for protocols is to think of them as different languages (and potentially vocabulary subsets) needed for communication. One such protocol, the hyper text transfer protocol (http for short), is the method used by our computers to connect to other computers that store text, images and other content that forms the basis for a webpage. Our ability to request this content, which is transferred over as data, and then converted by our browser into colors, images, text and other cool content, including links to other servers that have other data. When we click on a link on a webpage, it often takes us to another server where we can request information from that server instead. I would say that this collection of servers that store this content is the World Wide Web. I'll refer to the World Wide Web as the Web for short.

Think of the Web as a smaller part of the Internet.

As an example, many of you have played a game on the Internet, like Fortnite, in which your voice and game play actions were transferred to other computers so that your actions can be viewed by others in the game. However, you would not mention that you played Fortnite on the Web. Even though the web can display certain portions of the experience, like fortnite.gg (opens in a new tab). Those stats and being able to review them as well as leaderboards is a separate part from the game itself.

Here's one more example. BitTorrent is another way that computers end up talking to each other. It uses a specialized protocol often used for sharing large files (so I've heard 👀). While there may be web pages that provide more information, which would be on the Web, using it via the internet is what would cause you to potentially get into trouble if used on the university networks. However, visiting this site on the web that explains bittorrent in a web page format (opens in a new tab), should not cause you any issues, as you are only learning more about it. (Emphasis on should).

These are differences that you should be aware of.

OSI Model (7 Layers)

I won't say much here as the video sums it up quite nicely. Please watch this first (opens in a new tab)!

The important part though is that the internet works because it builds on top of a variety of structures. Most textbooks networking courses describe these as different layers. I won't be a big stickler in having you remember the names of each of the levels or anything. But I would rather you remember that each level works and builds on top of each other to perform different tasks, Similar to how computers and programming languages work in general, building higher level languages on top of lower level constructs, all the way down to binary 1's and 0's. In addition the OSI Model is conceptual more than technical, and each of the layers only ever talks to its neighboring layers to help with abstraction.

TCP/IP and its relation to the OSI Model

Here's another short video (opens in a new tab) that relates to TCP/IP to different layers.

I also wanted to provide a small table showing some of the most popular ports and their applications. A larger comprehensive listing can be seen on Wikipedia (opens in a new tab)

All of these different applications use these different ports to communicate with other computers about the particular information on that port. Some of these port numbers have been officially assigned, while others were unofficially claimed by application creators.

World Wide Web Primer

Watch this last video (opens in a new tab). From it, you'll learn more about:

• The World Wide Web
• Web Browsers
• Domain Name System (DNS) and how it translates to IP addresses
• Hosts files
• The anatomy of URLs
• The Hyper Text Transfer Protocol (HTTP)
  • Types
  • Status Codes

Specifically, you'll learn more about how the information is processed between our computers and a server.

Addendum about hosts

So if you try to do some hosts work on youro own, you may not get correct IP addresses. For example, previously if I had an IP address that I wanted to use for nintendo.com, the server (like Nintendo) may refuse answering to a direct IP address. There are some servers that do not allow you to access them via ip address directly, mostly because they are shared servers and many of the domains are under a single IP. Also, Edge does not support hosts files. The ghost of IE lives! Remember, editing hosts files is a "kids don't try this at home" (You've been warned), With hosts and it being an override, there is this temptation to play around, like for example having a line in your hosts file that points datamishandlers.com to 157.240.3.35. (I think you all can come up with something more entertaining for sure)

References and Further Reading

• [1] Tim Berners-Lee. 2010. Long live the web. Scientific American 303, 6 (2010), 80–85. Retrieved May 28, 2024 from https://www.jstor.org/stable/26002308 (opens in a new tab)
• [2] Barry M. Leiner, Vinton G. Cerf, David D. Clark, Robert E. Kahn, Leonard Kleinrock, Daniel C. Lynch Jon Postel, Larry G. Roberts, and Stephen Wolff. 2009. A brief history of the internet. SIGCOMM Comput. Commun. Rev. 39, 5 (October 2009), 22–31. https://doi.org/10.1145/1629607.1629613 (opens in a new tab)
• [3] Ben Segal. 1995. A short history of Internet protocols at CERN (opens in a new tab). (1995).