U1Ch2L13_HTTP&AbstractionOnTheInternet
Purpose: Students will get a basic understanding of what HTTP is.
Vocabulary: HTTP, Abstraction, Server, Client, TCP, URL,

• Abstraction: Reducing information and detail to focus on essential characteristics. It is typically possible to look at a system at many levels of abstraction, such as an “Internet Protocol Stack.”
• Server: A computer that awaits and responds to requests for data. (Example: a DNS server awaits and responds to requests for URLs to be translated to IP addresses.)
• Client: A computer that requests data stored on a server.

Example: When you type an address into your browser, your computer is the client and it sends the request to the DNS server.
!The important takeaway here is to understand that the system was constructed with layers of Abstraction where each layer only needs to concern itself with its specific job, and then hands it off to another layer.

Activity:  The Internet System – From Request to Response: Drawing & Explanation

• Include the following terms: TCP, IP, Router, DNS, Browser & URL, Client, Server & Human User.
• You are on your computer at home and want to access the high school website. Draw and explain how the terms above work together from the initial step of a request being made by a user on their computer to the final step when the user is viewing the information on their computer monitor. Please feel free to use your notes.
• DNS - The service that translates URLs to IP addresses.
• IP Address - A number assigned to any item that is connected to the Internet.
• TCP - Transmission Control Protocol - provides reliable, ordered, and error-checked delivery of a stream of packets on the internet. TCP is tightly linked with IP and usually seen as TCP/IP in writing.
• URL - An easy-to-remember address for calling a web page (like www.code.org).

HTTP:
Question: Where have you seen HTTP?
HTTP (HyperText Transfer Protocol) – It is the language/protocol that one computer uses to ask another computer to transmit a document (web page) over the Internet.

• ASCII text based protocol.
• Functions at the same level as DNS.

Video: https://www.youtube.com/watch?v=kBXQZMmiA4s&feature=youtu.be

Activity: Watch HTTP Traffic on Your Computer.
Open A Web Page in Explorer or Chrome: Tools/Developer Tools – Watch the Internet Traffic.
I used Chrome, select the 3dots to access Developer Tools/Network tab. I then went to Ford.com and Apple.
You will use your browser’s developer tools to discover what kind of HTTP traffic is associated with visiting different types of websites. You and your partner are going to look at least 5 different types of websites:

• http://example.com -- a very simple web page.  Use this first to investigate developer tools.
• A “static” website like: Wikipedia
• A news website like: ESPN.com, BuzzFeed, the New York Times, etc.
• A streaming site like: YouTube, or Spotify
• A site that accepts user input like: twitter, facebook, email, google docs.

For each type of website Above, Poke Around!

• Monitor the HTTP traffic generated by loading the page. Observe:
• Total amount of data received
• Number of HTTP requests actually generated by loading one page
• Total time to load the page.
• Types of data received through HTTP (it’s more than just HTML)

?Time Remaining? -> Take the online quiz at the end of U1Ch2L13