Lecture 20: Internet Intro to IT COSC1078 Introduction to Information Technology Lecture 20 Internet James Harland [email protected]
Lecture 20: Internet Intro to IT COSC1078 Introduction to Information Technology Lecture 20 Internet James Harland [email protected].
Apr 01, 2015
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Lecture 20: Internet Intro to IT
COSC1078 Introduction to Information Technology
Lecture 20
InternetJames Harland
Lecture 20: Internet Intro to IT
COSC1078 Introduction to Information Technology
Lecture 20
InternetJames Harland
Lecture 20: Internet Intro to IT
Introduction
James Harland• Email: [email protected]• URL: www.cs.rmit.edu.au/~jah• Phone: 9925 2045• Office: 14.10.1 • Consultation: Mon 4.30-5.30, • Thu 11.30-12.30
Who am I? And where do you find me?
Lecture 20: Internet Intro to IT
Introduction to IT
1 Introduction
2 Images
3 Audio
4 Video WebLearnTest 1
5 Binary Representation Assignment 1
6 Data Storage
7 Machine Processing
8 Operating Systems WebLearn Test 2
9 Processes Assignment 2
10 Internet
11 Internet Security WebLearn Test 3
12 Future of IT Assignment 3, Peer and Self Assessment
Lecture 20: Internet Intro to IT
Overview
Questions?
Assignment 3
Peer and Self Assessment
Internet
Questions?
Lecture 20: Internet Intro to IT
Assignment 2
Some initial comments
Some people have submitted .docx files. This will be penalised.
Some people have not included blogs on Blackboard. This will be penalised.
Some people have worked individually without permission. Guess what will happen ….
Lecture 20: Internet Intro to IT
Assignment 3
Reflect
Answer reflection questions from tutorials
See last lecture for ideas Research
Write about a particular IT topic of your choice (5-6 paragraphs)electronic voting, information security, 3D user interfaces, digital music, digital video, electronic commerce, natural language processing, DNA computing, quantum computing, cryptography, malware detection and removal, Moore's Law, green computing, …
Lecture 20: Internet SE Fundamentals
Self and Peer Assessment
How well has each person contributed to the group?
Evaluated over the entire semester
Assessed on process, not product
Work out a grade for each person (CR, DI etc)
Then convert this to a mark out of 20
Submit list of marks to tutor with justifications
Repeat previous step until the tutor is satisfied
See guidelines in Blackboard material
Lecture 20: Internet Intro to IT
Communications Developments ????: Writing 1440: Printing press 1844: Telegraph 1877: Telephone 1919: Radio 1928: Television 1969: ARPANET (Advanced Research
Projects Agency) 1970's: Internet Protocol (IP) 1984: Domain names (.com, .org, etc) 1991: World Wide Web
Lecture 20: Internet: Images Intro to IT
Number of Internet Hosts
1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
0
100000
200000
300000
400000
500000
600000
Internet
Originally designed to survive nuclear war
Grew out of army research into missile communication
Key role in breaking down the Berlin Wall
Lecture 20: Internet Intro to IT
Lecture 20: Internet Intro to IT
Internet
Dedicated channel:
two nodes exclusively use a single channel
works like traditional telephone
Packet switching:
break data down into packets
send packets from many users along link
can exploit redundancies and variations in network
Lecture 20: Internet Intro to IT
Protocols
Transmission Control Protocol (TCP):
basic necessities for data transfer
connection-oriented
Internet Protocol (IP):
data-oriented
necessary for packet-switched network
“Should run on two tin cans and a string”
There is an implementation for carrier pigeons ...
Lecture 20: Internet Intro to IT
Protocols
Lecture 20: Internet Intro to IT
Application Protocols
Define messages sent and data formats used
Generally known by user
Examples include HTTP, HTTPS, FTP, etc.
Often specified in resource identifiers
http://www.mysite.com:8080/info/mypage.htmlhttp://www.mysite.com:8080/info/mypage.htmlhttp://www.mysite.com:8080/info/mypage.htmlhttp://www.mysite.com:8080/info/mypage.html
Lecture 20: Internet Intro to IT
World Wide Web (WWW)
Combination of 4 different ideas:
Hypertext: information format for moving documents around
Markup Language: codes embedded in text indicating structure and presentation meaning
Resource Identifiers (URI, URL, ...)
Client-server model: client software requests resources from servers
Note WWW is not the Internet …
Lecture 20: Internet Intro to IT
Internet Uses
File transfer & remote services
Instant messaging
Web browsing
Peer to peer (P2P)
Telephony
Streaming media
“Web 2.0”
....
Lecture 19: Internet: Images Intro to IT
InternetLisa?Hi Dad!
Listen!Lisa?Hi Dad! Listen!
Lecture 20: Internet Intro to IT
Internet Structure
Application Application
Transport Transport
Network
Link
Network
Link
Mordor sucks!
2 dor1 Mor3 suc 4 ks!
1 2 3 49 5 6 2
14
3
22
1
3
4
2 3 1 49 5 6 2
2 dor1 Mor3 suc 4 ks!
Mordor sucks!
Lecture 20: Internet Intro to IT
Internet Structure
1 Mor
1
6
6
Lecture 20: Internet Intro to IT
Network Layer (Internet Protocol) Real intelligence is in the network layer
Adds next destination to packet
Not complete list of addresses
Sends to next destination
Retrieves final destination packets for this node
Passes them to the transport layer
Routing tables can be updated when disconnections occur
Hop counts used to stop endless looping
Lecture 20: Internet Intro to IT
Transport layer
Transmission Control Protocol (TCP) often used
User Datagram Protocol (UDP) becoming more common
TCP
Establishes connection first
Send and wait for acknowledgement
Reliable
Can adjust flow control to avoid congestion
Often best for email (which is not real-time)
Older
Lecture 20: Internet Intro to IT
Transport layer
UDP
Doesn’t establish connection
Just sends and forget
Efficient
No congestion adjustment
Works well for DNS lookup
Often used for Voice over Internet Protocol (VoIP) applications such as Skype
Lecture 20: Internet Intro to IT
Internet addresses
Unique 32-bit identifier (up to 4,294,967,296)
Soon to become 128-bit identifier
Managed by Internet Corporation for Assigned Names and Numbers (ICANN)
ISPs get “blocks” of addresses
32-bit string represented as N1.N2.N3.N4 where Ni
is in the range 0..255
17.12.25.0 means
00010001 00001100 00011001 00000000
Lecture 20: Internet Intro to IT
Internet addresses
Dotted decimal notation is still not very kind to humans …
www.sludgefacethemovie.com -> ??.??.??.??
Translation done by name servers which look up the Domain Name System (DNS)
Domains such as rmit.edu.au can be structured by the domain owner (eg goanna.cs.rmit.edu.au)
Lecture 20: Internet Intro to IT
IPv4 vs IPv6
Internet Protocol version 4 (used since 1981) 32-bit addresses Can handle “only’’ 4,294,967,296 unique
addresses Exhausted in February 2011 IPv6 uses 128-bit addresses IPv6 can handle “only” 3.4×1038 addresses IPv5 didn’t change the IPv4 address space
and wasn’t successful for other reasons …
Lecture 20: Internet Intro to IT
Conclusion
Work on Assignment 3
Name 5 people who are unaffected by the Internet …
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