The Internet and the World Wide Web ICS 61– Winter, 2015.
-
Upload
ralph-oliver -
Category
Documents
-
view
218 -
download
2
Transcript of The Internet and the World Wide Web ICS 61– Winter, 2015.
![Page 1: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/1.jpg)
The Internet and the World Wide Web
ICS 61– Winter, 2015
![Page 2: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/2.jpg)
Why computers?
Arithmetic Replicate human thinking Store and retrieve information Control other hardware Communicate Entertain Educate
![Page 3: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/3.jpg)
J. C. R. Licklider
Man-Computer Symbiosis, 1960:
The hope is that, in not too many years, human brains and computing machines will be coupled together very tightly, and that the resulting partnership will think as no human brain has ever thought and process data in a way not approached by the information-handling machines we know today.
![Page 4: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/4.jpg)
The “Galactic Network”
Licklider’s 1962 concept of a global computer network.
Also in 1962, Licklider became the first head of computer research at DARPA.
![Page 5: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/5.jpg)
2 Types of networks
Circuit switching Path decided on before data transmission starts Dedicated circuit (e.g. actual copper wire in early
telephony) Packet switching
Break message into small chunks (“packets”) Each chunk has a destination address inside Each chunk may take a different path from source
to destination
![Page 6: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/6.jpg)
Leonard Kleinrock
Proposed packet switching in 1960.
His computer at UCLA became the first node on the Internet in September, 1969. SRI UCSB Utah
Then called “Arpanet.”
![Page 7: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/7.jpg)
What do the packets look like?
Current system, called TCP/IP, was adopted by the Internet in 1983.
IP: Internet Protocol TCP: Transmission Control Protocol
![Page 8: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/8.jpg)
The IP Address
32 bits, written as four eight-bit (0-255) numbers
128.195.4.228 http://whatismyipaddress.com/
Originally, the first 8 bits specified the network, and the remaining 24 bits designated the computer on that network
New version of IP (v6) has 64 bit addresses http://www.nytimes.com/2011/02/15/technology/15internet.html?
scp=1&sq=internet%20addresses&st=cse
![Page 9: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/9.jpg)
Why Protocols are necessary
Big-endian v. little-endian Little-endian: later digits more significant
Intel x86 architecture Irvine CA USA
Big-endian: earlier digits more significant Motorola processors thirty two
![Page 10: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/10.jpg)
Why Protocols are necessary
Big-endian v. little-endian Little-endian: later digits more significant
Intel x86 architecture Irvine CA USA
Big-endian: earlier digits more significant Motorola processors thirty two
Blefuscu v. Lilliput in Gulliver’s Travels, 1726
![Page 11: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/11.jpg)
The IP Packet
IP Version number Total length of packet Source IP Address Destination IP Addr. Time To Live (TTL) Checksum Data being transmitted (000110100100101…)
No guarantee packets arrive, or arrive in order.
![Page 12: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/12.jpg)
TCP
Provides a “virtual circuit” between two computers. Defines a port HTTP: 80, IRC 194)
Guarantees reliable and in-order delivery of packets. TCP packets have sequence numbers. TCP programs at each end acknowledge packets
and resend if necessary. TCP practices congestion avoidance and
provides error checking.
![Page 13: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/13.jpg)
TCP/IP packet
![Page 14: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/14.jpg)
UDP
User Datagram Protocol “Lightweight” when compared to TCP,
doesn’t provide reliability or ordering. Same port facilities, provides error checking. Better for many time-sensitive purposes. Used for games, VoIP, IPTV.
![Page 15: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/15.jpg)
The Layers of the Network
Application Layer (FTP, HTTP, IMAP) Transport Layer (TCP, UDP) Network Layer (IP) Data Link Layer (802.11, Ethernet, WiMax) Physical Layer (Modems, Coax, Ethernet)
![Page 16: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/16.jpg)
The World Wide Web
Tim Berners-Lee, 1989 - 1991 “Any network-accessible information could be
referred to by a single ‘Universal Document Identifier.’”
More conventions, languages, and protocols: URL, HTML, HTTP
Mosaic (from NCSA), 1993-1995 Client-server architecture
![Page 17: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/17.jpg)
Uniform Resource Locator
![Page 18: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/18.jpg)
More URL
scheme://[user:password@]domain:port/path?query_string#fragment_id scheme: how to connect, e.g. https domain: where to connect port: optional (if omitted, determined by scheme) path, etc: what to ask for
query string: info for program, e.g. q=The+Stanley+Parable
fragment: position in document encodings: %2D = - %24 = $ %20, + = space
![Page 19: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/19.jpg)
Peer to Peer Architecture
Each computer is connected every other computer.
![Page 20: The Internet and the World Wide Web ICS 61– Winter, 2015.](https://reader036.fdocuments.us/reader036/viewer/2022062715/56649d6e5503460f94a4f7ec/html5/thumbnails/20.jpg)
Client-Server Architecture
Client:•Rendering•Sound•Some rules•Some physics
Server:•Game State•All rules•All physics•All AI