COMPSCI 92L Lecture Notes - Lecture 2: Certificate Authority, Hypertext Transfer Protocol, Tim Wu
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11 May 2016
School
Department
Course
Professor
COMPSCI 92L
Astrachan
Spring 2016
1-27-16
Lecture 2: Web/Internet/Algorithms
● CS depends a lot on scaling and timing
● Content Distribution Networks (CDN) - allows replication of material synced throughout
websites across the world
○ displayed in URL of Facebook photo
● Internet is different type of network than cell/landline network
● Internet - network of autonomous systems (network of networks), packet-switched
network
● different networks affect how network traffic gets between an area’s receptors
○ ex. Zimbabwe’s Netflix network is different from those of US’s since Zimbabwe
just got Netflix access
● “bits v atoms” coined by Nicholas Negroponte
○ bits can be generated differently for free so that every person can watch an
episode at the same time (ex. Netflix episode)
○ atoms are physically tangible and can be copied (ex. copy of a Redbox DVD)
■ DVDs are designed to make it difficult to copy
○ more atoms in the world than iPv6 addresses (10^80 > 2^128)
● HTML 5: standard for web development
○ information from server to client rendered in a browser
○ platform differences b/w phone, laptop OS
■ ex. websites that adjust formatting according to what “Markup” you’re on
(phone markup, laptop markup, etc)
■ some smart websites automatically take this into account
● HTML’s webpage has another layer, JavaScript
○ interactive webpages, client, server
○ benefits of interacting client-side
○ drawbacks of not going to server
● UI/UX interaction w/ app/pages
● HTTP: Hypertext Transport Protocol
● browser renders the program to make it displayable on devices
● “view page source” (R click on a webpage) gives meta JavaScript codes
● “inspect” gives:
○ elements: JS code
○ styles: colors
● IPv4: 2^32, IPv6: 2^128
○ 4 bit standard to help route packets through the internet
○ Internet Engineering Force
● non-static webpages because traffic goes back and forth
● servers: Apache, NGINX, IIS7 (hardware + software + abstraction)
find more resources at oneclass.com
find more resources at oneclass.com