The World Wide Web
The concept of the WWW was first implemented by Tim Berners-Lee of
CERN (European Laboratory for Particle Physics) in March, 1989.
Berners-Lee intended to create a wide-area hypermedia information
retrieval system giving universal access to a large universe of
documents. Originally aimed at the High Energy Physics community, it
has spread to other areas and attracted much interest in user support,
resource discovery, and collaborative work. Currently, it is the most
advanced information system deployed on the Internet, and is equipped
to embrace many future advances in technology, including new networks,
protocols, and data formats.
Although the WWW was originally intended only to link documents,
recent advancements have expanded this concept. It is now possible to
transmit picture files, audio files, and even movies stored in a
variety of different formats (assuming the user has software to
support the different files). In addition, the WWW can support
documents written in PostScript, ASCII, and HTML among others.
Over the past few years, the WWW has grown at a phenomenal rate. As of
January 1993, the WWW was ranked 127th of all network services in
terms of sheer byte traffic. That August, the WWW was ranked 13th. In
addition, the amount of byte traffic across the National Science
Foundation's North American network attributed to WWW use multiplied
by 414 times during this period ("Entering
the World Wide Web: A Guide to Cyberspace", Kevin Hughes).
Imagine thousands of computers worldwide wishing to view the same
group of documents. Without any type of communication system, these
documents would have to be located on each computer, thus requiring
tremendous disk space and numerous copies of each document. Now
imagine a system of common links connecting all of these computers
together (the Internet). These computers can now "talk" to each other,
and can be given access to the same documents without needing to store
a copy on their own computer. But how do they get these documents?
There are many transfer methods (protocols) to choose from, but each
computer would need to have access to every protocol to obtain every
available document. Or, they could have access to only one
information system which could support almost every protocol available
(The World Wide Web). This is why the WWW was created.
The first things to decide, when making information available, is
which protocol to use. Different protocols have various strengths,
relative to intended use and data formats, for instance. The following
is a list of the protocols supported by the WWW, a description of
their capabilities, and a suggestion of when each should be used.
- WAIS
- Description: The Wide
Area Information Server (WAIS) automates the search and retrieval
of many forms of electronic information over wide area networks. Its
primary use is to search through documents for keywords and display
any matches occurring in its database.
- Information Retrieval: WAIS
is very useful to find available documents relating to a certain
subject in a particular database.
- Information Dissemination: WAIS
should be used when a person wishes to make a document available and
expects the user will locate this document using a keyword search.
- Network News
- Description: The
Network News protocol provides a list of Internet newsgroups
sorted by area of interest. A newsgroup is a group of articles written
by various users throughout the Internet on a specific topic.
- Information Retrieval: Network
News allows users to browse or read available news articles by
simply clicking on them.
- Information Dissemination: Network
News is used only for newsgroups and does not support any other
forms of information dissemination.
- Gopher
- Description: Gopher,
also known as the "Internet Gopher" allows users to browse for
resources using menus. When users find something they like, they can
read or access it through Gopher
without having to worry about domain names, IP addresses, etc.
- Information Retrieval: Gopher
is used when the geographical location of a document or group of
documents is known. For example, to view "The Guide to NIST",
first click on North America from the main menu, then
USA, then Maryland, then NIST, then NIST
General Information, and then Guide to NIST.
- Information Dissemination: Gopher
should be used when it is anticipated that the user will be accessing
a document by its geographical location. Gopher can also support
directory hierarchies, which allow documents to be grouped and
therefore be easier to locate in a directory structure.
- Telnet
- Description: Telnet allows users to
connect to a specified remote machine and appear as if they were
working from that machine. The user must have the necessary
permissions (as determined by the system administrator) to telnet
successfully.
- Information Retrieval: Telnet is primarily used to
run applications on remote machines that are not available on a user's
machine. Some possible applications are archie, gopher, WAIS, and
veronica. Specific logins are needed for different applications.
- Information Dissemination: Telnet should be used to
make an application available to the public. It should not be used to
make non-executable files, such as publications, available.
- Anonymous FTP
- Description: File Transfer
Protocol (FTP) transfers files to and from a remote network site.
Anonymous FTP is an anonymous version of FTP; the available
directories are generally restricted through user permissions. In this
instance, users would login as anonymous instead of using
their actual login name. This is permitted only when the remote site
is set up for such a login.
- Information Retrieval: FTP is used
to transfer a file when the exact location of the file is known.
Navigating through a directory structure and listing of the files in a
particular directory are supported. Viewing the contents of a file is
not supported. FTP should only be used to transfer a file from one
location to another.
- Information Dissemination: Anonymous
FTP should be used to make a file or group of files available to
the public to copy. It should not be used when the user may wish to
view the file before copying it.
- Whois
- Description: Whois
is a simple internet telephone book system. A list of colleges and
organizations is provided as an entry menu, each linked to their
respective electronic telephone listing. Once a location is selected
and a name is entered, a keyword search is performed to find the
telephone number of the person requested.
- Information Retrieval: Whois
is used to find out information about a particular person when their
organization is known.
- Information Dissemination: Whois
should be used only to make information about staff (email address,
phone numbers) available.
- HTTP
- Description: Hypertext
Transfer Protocol (HTTP) is used to transfer documents written in
Hypertext Markup Language (HTML). It
has the lightness and speed necessary for a distributed collaborative
hypermedia information system.
- Information Retrieval: HTTP
should be used with a WWW browser to access documents written in HTML when the URL is known.
- Information Dissemination: HTTP
is used for documents written in HTML.
Such documents must reside on a server that supports HTTP access.
Computers communicate with each other by various methods. One method
is the client-server method. One system serves the request(s)
of another (client) system. This model has been adopted in
information dissemination and retrieval processes.
A client is a software package located on the user's machine which
allows access to documents in the WWW. Clients usually provide an
attractive user interface that allows movement through documents to be
as easy as a touch of a button. Although Mosaic is a popular WWW
client, there are many other clients
available. Different clients (also known as browsers) are available
for different platforms.
A server is a program normally located on a remote machine which
responds to incoming connections by a client and provides a service.
There are many varieties of WWW
server software to serve different forms of data.
Any user wishing to access information through the WWW must use a
client. In addition, any information made available must be done so
through a server. When users type the URL of the document they wish to view, the
client searches for the server which handles that URL and "asks" for the document using the
specified protocol. The server finds the document and "hands" it to
the client for viewing. The document only resides on the client's
machine while being viewed. This entire process happens relatively
quickly (between a couple seconds and a couple minutes) - even if the
connection stretches to the other side of the world!
There are many other references which go into further detail regarding
what the WWW and the Internet offer. Many of them are located online.
Some books that were used to help write this document are:
Complete citations are available in the references section.
You may also want to:
Last Edited: Tuesday, 23-Jul-1996 13:55:14 EDT
Written by: Craig
Schlenoff