ise554 the www for elearning 3.1 www concepts. “the www principle of universal readership is that...

ISE554

The WWW for eLearning

3.1 WWW Concepts

“The WWW principle of universal readership is that once information is available, it should be accessible from any

type of computer, in any country, and an (authorized) person should only have to use one simple program to

access it. ”

The World Wide Web

was developed in 1989 by Tim Berners-Lee

of the European Particle Physics Lab (CERN) in

Switzerland

NCSA Mosaic

was originally designed and programmed for X by Marc Andreessen and Eric Bina at NCSA.

Version1.0 was released in April, 1993.

Version 2.0 was released in December 1993, along with version 1.0 releases for both the

Apple Macintosh and Microsoft Windows

Tim Berners-Lee’s slides to introduce the WWW (1993)

Tim Berners-Lee

Tim Berners-Lee

“The WWW uses hypertext as the method of presentation... links can lead from all or part of a document to all or part of

another document.

Documents need not be text: they can be graphics, movies and sound, so the term hypermedia (multimedia hypertext)

applies equally well to the WWW.”

Tim Berners-Lee

“Whilst hypertext is a powerful tool for finding information, it cannot cope with large amorphous masses of data. For

these cases, computer-generated indexes allow the user to pick

out interesting items from textual input.”

“Whilst hypertext is a powerful tool for finding information, it cannot cope with large amorphous masses of data. For

these cases, computer-generated indexes allow the user to pick

out interesting items from textual input. There are therefore two operations a reader can use: the hypertext jump and

the text search.”

Tim Berners-Lee

“The web ... was designed without any centralized facility... There is no central control.

To publish data you run a server, and to read data you run a client.”

Tim Berners-Lee

“A feature of HTTP is that the client sends a list of the representations it understands along with its request, and

the server can then ensure that it replies in a suitable way.”

Internet protocolsSets of rules that allow for inter-machine communication

on the Internet.

E-mail (Simple Mail Transport Protocol or SMTP) Telnet (Telnet Protocol)

FTP (File Transfer Protocol) Usenet (Network News Transfer Protocol or NNTP)

HTTP (HyperText Transfer Protocol)

Anatomy of a URL

For example, the URL of the home page of the House Committee on Agriculture of the U.S.A. House of Representatives:

http://www.house.gov/agriculture/schedule.htm

1.Protocol: http 2.Host computer name: www 3.Second-level domain name: house 4.Top-level domain name: gov 5.Directory name: agriculture 6.File name: schedule.htm

Domain name examples

.com commercial enterprise .edu educational institution .gov U.S. government entity .mil U.S. military entity .net network access provider .org usually non-profit organizations

Languages

CGI JAVA

VRML XML

Languages

CGIprograms for data that conforms to the CGI specificationJAVA

VRML XML

Languages

CGIprograms for data that conforms to the CGI specificationJAVA"Write once, run anywhere.”VRML XML

Languages

CGIprograms for data that conforms to the CGI specificationJAVA"Write once, run anywhere.”VRMLfor the creation of three-dimensional worldsXML

Languages

CGIprograms for data that conforms to the CGI specificationJAVA"Write once, run anywhere.”VRMLfor the creation of three-dimensional worldsXML“to separate form from content”

A method for graphical input on the WWW

Lesley Parks & Ernest Edmonds

The objects were constructed from a combination of graphics primitives (lines,

circles, ellipses, boxes) with semantic information (constraints & textual descriptions). The data defining such an object was capable of being stored in and retrieved from a knowledge base accessible from a Web server. The results

of the user's interaction with the object was to be returned to the server.

Knowledge Server

Browser

Knowledge Server

Browser

Knowledge Server

Browser(face,x,y,z)

Good design

Animation and fun

Superbad.com

“There is no reason why anyone would want to have a computer in their home”

Ken Olson, President of DEC, 1977

Study these links provided from the web site

Laura Cohen: Understanding the World Wide Web

World Wide Web Consortium