topic 11
The Internet & WWW
the Internet
• worldwide connection of thousands of computer networks.
• these networks use a common language to communicate.
• transmission Control Protocol/Internet Protocol (TCP/IP)
– enables instantaneous transmission/reception of digital data
• the Internet is a cooperative community of networks.
• no particular body owns the internet.
the network
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the Internet is structured in an ‘hierarchical form’.
more than 500,000 networks in more than 150 countries.
bandwidth
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communication channels carry data on the Internet backbone
bandwidth- is a channel’s data carrying capacity.
bandwidth =
no. of bits of information passed/second
different Internet channels
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phone Lines (twisted pair)
coaxial cable
fibre Optics
microwave
satellite
http://www.southerncrosscables.com/media/user/images/submarinegraphic.jpg
fibre-optic cable
the Internet in Australia
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Australian telecommunication agencies carry internet traffic on
the Telstra backbone
Internet provided and maintained by Telstra Internet Direct
Telstra’s domestic internet capacity
– 1997 100Mbps
– 1999 1,000Mbps
– 2004 10,000Mbps
broadband connectivity
- fibre optic
- satellite
- microwave
tcp/ip
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TCP/IP
– data transmission protocol on which Internet is based.
– breaks Internet data into small ‘Information Packets’.
– each packet contains the data and the address where it is
being sent.
Routers
– computers routing ‘Information Packets’ through channels
to destinations.
TCP/IP
– keeps records of original data for rearranging packets in
correct order on arrival at destination.
internet traffic
Internet addresses
• IP address
• each computer on the Internet has a unique IP number.
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it consists of ‘4 bytes’, numbers ‘0 and 255’, separated by
periods
eg- 139.230.169.149
email
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e-mail is electronic transmission and reception of messages
between users on the Internet.
each user has a unique ‘e-mail’ address.
– eg- john@hotmail.com
– where ‘john’ is username, ‘hotmail.com’ is the domain.
an e-mail consists of
– ‘Title:’ or ‘To:’
– ‘Body’
– ‘Signature’
peer 2 peer
• two (or more) computers linked directly to each other
via their IP numbers
• allows real-time communication between machines
• some systems use servers to identify machines on
the network
• examples:
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ICQ
CU-SeeMe
MSN Messager
Skype (voice over IP)
voice over IP
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voice messages sent as packets over the Internet
computer to computer
computer to phone
operates on local area networks
many extra services
videoconferencing
• enables people to see and speak
• previously required dedicated lines
• bandwidth hungry
remote control
• Internet used to control devices remotely
World Wide Web
• most commonly used method of accessing
information the internet
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sound
graphics
animation
interactivity
a browser
tracking
assignment submission
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5 MB limit
all files in one folder
create archive of the folder
Send by email, lars@larsagundersen.no
Verify that I send a reply confirming that I have
received submission
• keep a copy in case!!
exam
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covering lecture content
2 hours + 5 mins reading
20 multi-guess (10 marks)
20 short answer (20 marks)
– brief responses and point form is encouraged
Web Searching
search engines
keyword searching
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easy to perform
strong returns
broad results
can be refined
search strings
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“John Howard” (the phrase)
John +Howard (the 2 words)
John or Howard (either word)
John -Howard (John but not Howard)
John * Howard (John and Howard separated by a
word)
• ~vehicle history (history and vehicle or synonyms)
advanced operators (Google)
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enrolments site:www.ecu.edu.au (this site only)
elections date:3 (last 3 months)
link:www.ecu.edu.au (pages with this link)
info:www.ecu.edu.au (information about this site)
related:www.ecu.edu.au (sites related to this site)
how search engines work
http://www.link2city.com/images/search-engine_-spider.gif
Google page ranking
• used to create a relevance rate for pages
• based on pages that link to a page
• relevance of a page determined by relevance of its
linking pages
• algorithm has 500 million variables, 2 million terms
• previous algorithms eg HotBot used number of links
to determine relevance
the search
synonyms
• I want to find out how many people are using the
Internet
• keywords
– Internet, usage, statistics
• I want to find out what jobs are available for digital
media graduates
– employment, occupations, opportunities multimedia, “digital
media”
meta search engines
• Dogpile
• Vivisimo
• MetaCrawler
• all4one
• search.com
specialty databases
• findlaw
• achoo
• beaucoup
• imdb
page visibility factors
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keywords in URL
keywords in page title
keywords as metatags
keywords as headings
keywords in bold face or large font size
keywords in text
reciprocal linkage text (links to the page)
URL extension eg. gov, edu, net, org