Lesson 13: HTTP and Abstraction on the Internet
Objectives:
Students will be able to:
Explain how layers of protocols allow the Internet to function.
Use developer tools in a modern browser to explore the HTTP traffic associated with visiting common websites.
Identify abstractions used in the development of Internet protocols.
Describe how a protocol or layer of the internet acts as an "abstraction" for other layers
Vocabulary
DNS - The service that translates URLs to IP addresses.
HTTP - HyperText Transfer Protocol - the protocol used for transmitting web pages over the Internet
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).
Journal – Activity
Prompt: today we are going to talk about HTTP and Abstraction on the Internet. Turn to your neighbor and define what you think the word abstraction means.
We’re rounding out our understanding of how the many protocols and systems of the Internet work together to make the Internet function.
We want to think of the protocols as working in “layers”.
This picture here (also on first 2 pages of HTTP and Abstraction on the Internet - Resource) is a simplified version of what’s known as the “Internet Protocol Stack.” We’ve studied each layer separately but now you can begin to see how they work together.
We imagine outgoing information going DOWN the stack and incoming information going UP the stack.
All of this happens in the network software on each computer, whether that computer is your phone, a laptop, or a server like a DNS or web server (routers are a special case that only look at the IP layer).
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. This makes the very complicated task of digital network communication possible.
At the top layer, for example, DNS just thinks is “speaking DNS” to some other computer - the DNS protocol does not even need to know how the other layers work It just relies on them doing their jobs.
Where do you see the words HTTP?
Activity – In your journal create a list of all the things you already know about HTTP
Video Link: The Internet: HTTP and HTML - Video
Activity – HTTP in Action – Activity Guide – Pair Activity
Follow directions on the Activity Guide. At the conclusion of the Activity answer the following questions. Staple your answers to the Activity guide and turn in both completed forms to the in box.
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