Vocabulary Prototype: A preliminary sketch of an idea or model for something new. It’s the original drawing from which something real might be built or created. Binary - A way of representing information using only two options. Bit - A contraction of "Binary Digit". A bit is the single unit of information in a computer, typically represented as a 0 or 1. Bandwidth - Transmission capacity measure by bit rate Bit rate - (sometimes written bitrate) the number of bits that are conveyed or processed per unit of time. e.g. 8 bits/sec. Latency - Time it takes for a bit to travel from its sender to its receiver. Protocol - A set of rules governing the exchange or transmission of data between devices. ASCII - ASCII - American Standard Code for Information Interchange. ASCII is the universally recognized raw text format that any computer can understand. code - (v) to write code, or to write instructions for a computer. IETF - Internet Engineering Task Force - develops and promotes voluntary Internet standards and protocols, in particular the standards that comprise the Internet protocol suite (TCP/IP). Internet - A group of computers and servers that are connected to each other. Net Neutrality - the principle that all Internet traffic should be treated equally by Internet Service Providers. To / From Address: Like an IP address, included on every message sent over the Internet. Dropped Messages: Poorly formed messages cannot be delivered and so are dropped, just like a letter with a bad address on it. Tomorrow you’ll discuss more technical reasons messages are dropped. Multiple Hops: A message travelling across the Internet will visit many routers as each tries to forward it along the most efficient path to its destination. Different Paths: Routers respond to traffic on the Internet in real time. The best path at one moment might be backed up a few seconds later. Routers choose the current best path to get the message through Router: a computer designed to receive and redirect packets of information based upon the addressing information (e.g. an IP address) contained in the packet. Packets - Small chunks of information that have been carefully formed from larger chunks of information. 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. 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. URL - An easy-to-remember address for calling a web page (like www.code.org).

U1L13 HTTP and Abstraction on the Internet CS Principles U1L13 HTTP and Abstraction on the Internet

U1L13 HTTP and Abstraction on the Internet Objectives SWBAT: 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.

U1L13 Vocab 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). Abstraction: Reducing information and detail to focus on essential characteristics. It is typically possible to look at a system at many levels of abstraction, depending on how much detail is necessary to approach the challenge at hand. Server: A computer that awaits and responds to requests for data Client: A computer that requests data stored on a server

HTTP HTTP like DNS is an ASCII-text based protocol - it’s just two computers sending text messages to each other. What makes it a protocol are the rules of the “conversation” the two machines are having. It is a call-and-response protocol for a client/server relationship, where a client requests a web page or other content (image, sound, video, etc.) from a server. The server looks for it and sends it back. HTTP is a “high level” protocol that sits on top of all the other protocols and internet systems. The text message conversation between the computers is being broken up into TCP/IP packets, and all the data gets sent as bits over wires and airwaves, taking different paths, and it gets interpreted reassembled at the end. This is a perfect example of abstraction on the Internet, as one layer makes use of the functionality provided by the layer below it, without worrying about the details of how this functionality is achieved. HTTP doesn’t have to worry about anything other than the text protocol of HTTP works. The network software and devices on your and others’ computers handle looking up addresses, breaking down data, packeting, routing, transmission and interpretation and reassembly.

HTTP (HyperText Transfer Protocol) HTTP is a high level protocol, that defines how users of the Internet (clients) request and receive data like web pages, images, video, audio, and files from the servers containing them. A client will send a request to the server with an identifier for a desired piece of data, and the server will attempt to respond to the request, typically by returning the information requested.

 

Investigate HTTP traffic on your computer We can actually watch HTTP traffic on our computers through tools in the web browser! In pairs, open and complete HTTP in Action - Worksheet During the activity: Access the developer tools of their browser. Monitor the HTTP traffic generated by visiting a variety of websites. Record their findings, using the resource as a guide.