CP1030 - Introduction to Information Technology
Semester 2, 1999

The Internet

What is it?

A wide area network (WAN) that links millions of computers worldwide.
Began in 1969 as a research network ARPANET:
- ARPANET scientists developed the Internet protocols (TCP/IP), standards that enable the transfer of data through the Internet,
- sponsored by the US government,
- linked Dept of Defence research centres and university researchers.
Other universities joined...
- the net keeps growing with 150,000 new users per month (accurate?).
- current estimate: 25 million users in 147 countries (old estimate).
Note that an internet (lowercase i) is any network of networks, but
THE Internet (capital i) refers to the global network that anyone can access.
This is a common mistake.

Genesis

The Web began at CERN, the European Centre for Nuclear Research.
CERN has several accelerators
- Large teams of physicists use the accelerators for particle physics research
- These teams may be scattered through many European countries
- Experiments are extremely complex and require yeats of advance planning and construction of equipment
- The web grew out of the need to have these large teams of dispersed researchers collaborate with a large collection of constantly changing documents
  - reports
  - blueprints
  - drawings
  - photos
  - others...
A CERN physicist, Tim Berners-Lee proposed a web of linked documents in March 1989
First operational prototype of the web was running 18 months later
The first graphical interface for the web was released in February 1993, and was called Mosaic
Mosaic was so popular, its author, Marc Andreessen, left the NCSA (National Centre for Supercomputing Applications) and founded Netscape Communications Corporation.

(More on networks later in the course)

So Why the Success?

Design:
- The Internet was designed during the cold war.
- If it was built around a central office, it could be easily disabled.
- Therefore if one Internet node fails information is transfered or rerouted around the broken node.
Implications:
- No one person or organisation owns the Internet.
- Anyone can add a new node (computer or LAN) to the Internet.
- The consumers are also the producers.
Computers initially isolated people
- hard to use
- needed mathematical or electronic background
- new language
- new ideas and concepts
- computer were not a communication device
- fear (largely superficial apparent ominous complexity)
The Internet
- needs little technical information
- is based on information rather than technology
- provides a sense of community
Internet users are also very protective
- netiquette - a self-regulated system of behavior
- Blue ribbon campaign - to stop Internet censorship
Hype:
- "Internet" and "Web" etc. are buzz words.
- Internet is one of the main reasons people are buying PCs these days
MONEY!
- Businesses are making money, web designers, advertisers (hotmail)
- e-commerce is big business
- businesses without a web site appear inferior

Internet Access

Direct Access
- Uses a direct network connection to the Internet
  using the TCP/IP network protocol to transfer information.
Dial-in Access
- You use a modem to connect to a computer which has direct access.
- You need special software conforming to the
  - serial line Internet protocol (SLIP), or
  - point-to-point protocol (PPP).
- These internal protocols are designed to improve communication through telephone lines.
- With SLIP/PPP access you can:
  - view graphics
  - run graphical applications (eg. Netscape)
- Without, you are limited to text-based displays.

Limitations of the Internet

Not suited for transferring real-time voice and video.
The connection between two computers on the Internet is not guaranteed.
Transfer rates can be fast or quite slow depending on:
- the time of day,
- the amount of network traffic, and
- the weather.

Uses of the Internet

electronic mail
Usenet newsgroups
file exchange
Gopher & Wais
World Wide Web

Electronic Mail

Used to send messages to other Internet users all over world.
- Very efficient - send and receive a reply within minutes.
- Typically less formal than pen and paper.
To send a message to someone you need an address.
An address comprises two components:
- User name - identifies the sender or recipient
- Domain name - identifies the computer system on which the user has an account
For example, to comment on the course, send me a message at either:
```
Lindsay.Ward@jcu.edu.au
lindsay@cs.jcu.edu.au
```

Mailing Lists

Often groups of people with a similar interest will form a mailing list.
For example - cp1030@jcu.edu.au.
Any mail message sent to the list gets reposted to each member of the list.
Lists can be moderated by an administrator or unmoderated.
You subscribe/unsubscribe by emailing the list administrator.
When the list becomes large:
- a more diverse range of people are in the list
- the volume of mail increases
- the volume of relevant mail decreases
- probably better to start a news list or web page

Netiquette

The peril of email:
- You read a message.
- It makes you angry.
- You reply...
- You calm down.
- You reread the message.
- You've over-reacted or misread the message...
For important messages consider seriously your reply over time.
Don't send junk mail or advertising material.
When using mailing lists:
- read the list for a while before mailing a message,
- make sure your message is relevant and concise,
- don't reproduce private communications without consent,
- send (un)subscription requests and personal emails to the administrator, not to the list.

Usenet News

Usenet is a world-wide distributed discussion system.
Consists of a set of newsgroups.
Newgroups are named hierarchically by subject.
There are thousands in number!

For example:

alt.beer       alt.buddha.short.fat.guy
aus.ads.jobs   jcu.forsale
jcu.announce   rec.aviation.aerobatics
rec.guns       rec.bicycles.off-road

Articles or messages are posted to newsgroups.
The articles are then broadcast to other interconnected computer systems.
Anyone (with appropriate software) can post & read news messages.
Netiquette:
- Firstly read the group news.answers.
  - Answers for frequently asked questions (FAQs).
  - Guideline for posting messages.
- Read the newsgroup for a week or so before posting a message.
- Don't flame other news users.
  - Reduce the discussion to a personal level.

File Transfer (FTP)

The transfer of files and programs.
- typically from a public archive
- also between different computer systems to which you have access
Uses the File Transfer Protocol (FTP)
FTP archives can be searched by file name using the program archie.

Gopher & WAIS

Client-Server based information retrieval systems.
Once at a server you can:
- retrieve information via a text-based menu
- search the server by content or file-name
- use a link to go to another server

Limitations of FTP, Gopher & WAIS

FTP, Gopher & Wais were developed with text-based user-interfaces.
Files were retrieved and stored on the local machine.
Separate programs were needed to access the information depending on the type of file.
Once computers and networks became powerful and affordable enough to
- automate the file retrieval,
- display multimedia documents
the World Wide Web was possible.

The World Wide Web (Web, WWW or W3)

A world wide hypermedia system.
Documents on the web contain multimedia formats:
- Text
- Images & Figures
- Animation & Video
- Sound
Also contain hyperlinks to other documents stored anywhere on the web.
- Appear as:
  - highlighted or underlined images or text,
  - icons, or
  - hotspots in images.
Programs
- Browser (Netscape, Internet Explorer, others)
- Plug-ins - used to view content that the browser doesn't understand (extends its functionality)

Addressing

The Uniform Resource Locator (URL)

For example, http://www.blah.com/ is a URL. It gives the exact path to the page. This path can be followed from anywhere. It is called an absolute address since it is ABSOLUTELY specified. It can only be interpretted in one way.

URLS are a textual (easy) way to represent an Internet Protocal (IP) number, which identifies a computer on the Internet (more on this in Data Communications).
e.g. 207.46.131.137 is the IP# for the URL http://www.microsoft.com.
Once at that computer though, there can be many different web sites and pages with different URLs.

Internet addresses begin with http://

Often www follows (stands for World Wide Web), but not always.

Email uses the same system, but instead of specifying a page after the web site (domain)
(e.g. cs.jcu.edu.au/~lindsay)
a user's address is included before the site, with an @ separating
(e.g. lindsay@cs.jcu.edu.au)

Organisation	Code	Country	Code
Commercial organisation	com	Australia	au
Educational institution	edu	Canada	ca
US government organisation	gov	Germany	de
US military organisation	mil	France	fr
Networking organisation	net	Japan	jp
Private organisation	org	United Kingdom	uk

CP1030 - Introduction to Information Technology Semester 2, 1999