The Internet and Intranets
Objectives
Define the Internet and the World Wide Web
Visual, audio, and animation
Construct a timeline showing the Internet’s history
Explain the Web’s client/server nature
Understand the construction process for Web sites
Explain the Web’s business potential
List Web risks and limitations
Internet Basics
Largest machine ever developed
Currently, 100 million plus web sites
The Internet's graphical portion is known as the World Wide Web (WWW)
Web tutorials abound on the web. For example:
http://teche.cacs.usl.edu/tutorial/internet/cmu-www/outline.html
Pre-History
While the Internet began in 1969, it had been conceived considerably
earlier.
Vannevar Bush’s article “As We May Think” in the July 1945 Atlantic.
Bush credits Emerson, Leibnitz, and Babbage.
History
The Internet began in 1969 through a grant project from DARPA (Defense
Advanced Research Projects Agency)
The grants funded research into a decentralized communications system
that would not be dependent on any single physical site.
The web is based on ‘open standards’.
Ownership
In a decentralized structure, there is no central authority.
1983 the Term ‘Internet’ Appears
TCP/IP becomes the only set of network protocols used on ARPANET.
Generates the use of the term "Internet" as the network of networks which
either use the TCP/IP protocols or are able to interact with TCP/IP networks.
1982-1983 Desktop Computers
Desktop computers began to appear on the Web.
Many Desktop Computers come equipped with Berkeley UNIX, which includes
networking software that allows for relatively easy Internet connectivity.
1985-86 NSFNET Appears
The National Science Foundation (NSF) connected the nation's six supercomputing
centers together in a network called NSFNET, or NSFNET backbone.
The NSF supported institutions, such as universities, in their efforts
to connect to the regional networks which expanded access to the Internet.
1987
NSF awards a grant to Merit Network, Inc. to operate and manage future
development of the NSFNET backbone.
Merit Network, Inc. collaborates with International Business Machines
(IBM) Corporation and MCI Telecommunications Corporation to research and
develop faster networking technologies.
1989
Backbone is upgraded to "T1".
Able to transmit data at speeds of 1.5 million bits of data per second,
or about 50 pages of text per second.
‘93 Hypertext Transport Protocol
The European Laboratory for Particle Physics in Switzerland (CERN)
releases the World Wide Web (WWW).
– Developed by Tim Berners-Lee.
Utilizes hypertext transfer protocol (HTTP) and hypertext links,
– Changes the way information can be organized, presented and accessed
on the Internet.
1993, Backbone Upgrade
NSFNET backbone network is upgraded to "T3”.
Able to transmit data at speeds of 45 million bits of data per second,
or about 1400 pages of text per second.
1993-1994 Graphical Browsers
Graphical web browsers Mosaic and Netscape Navigator are introduced.
Due to their intuitive nature and graphical interface, these browsers
make the WWW and the Internet more appealing to the general public.
1995 New Network Architecture
The NSFNET backbone is replaced by a new network architecture, called
vBNS (very high speed backbone network system) that utilizes Network Service
Providers, regional networks and Network Access Points (NAPs).
The World Wide Web and HTTP
Allow you to create "links" from one piece of information to another.
Can incorporate references to media objects such as sounds, graphics,
and movies.
Web Pages
The Web presents information as a series of "documents," often referred
to as web pages, that are prepared using the Hypertext Markup Language
(HTML).
Hypertext Markup Language (HTML)
Using HTML, special sections of the document can "point" to other
information resources.
These special sections are called hypertext links.
Users viewing the webpage can select the hypertext link to retrieve or
connect to the information resource that the link is pointed toward.
Hypertext Links
Hypertext "links" can lead to other documents, sounds, images, databases
(like library catalogs), or e-mail addresses.
Non-linear Navigation
The World Wide Web is non-linear.
Non-linear means you do not have to follow a hierarchical path to resources.
Any of the shown paths will work.
Electronic mail or E-mail
Allows information to be sent between computers and people on the Internet.
The most widely used Internet resource.
Can be sent to multiple recipients.
E-mail Address Structure
Basic structure:
–username@host.subdomain.second-level-domain.first-level-domain
Two examples:
janedoe@sales.nw.widgets.com
johndoe@widgets.com
E-mail Address Structure Explained
"johndoe" is the name of the person sending or receiving the message;
that is, the username.
"widgets" is part of the domain name of the organization
"com" is also part of the domain name and indicates that widgets is
a commercial organization.
TCP/IP Protocol Suite
Internet mail works because of SMTP, Simple Mail Transfer Protocol.
SMTP is part of the TCP/IP suite of protocols.
SMTP is a protocol, or set of rules that enables electronic mail to
move through the Internet. Through SMTP, a UNIX machine can send mail to
a PC or Macintosh computer and vice versa.
What is an IP Address?
An IP (Internet Protocol) address is an identifier for a particular
machine on a particular network.
IP addresses are also referred to as IP numbers and Internet addresses.
Each machine on the Internet must have a unique IP address.
IP Address Form
An IP address consists of four sections separated by periods.
Each section contains a number ranging from 0 to 255.
Example = 198.41.0.52
Domains
Each Internet server is assigned to a domain.
Major Domains include:
– .com
– .edu
– .gov
– .org
– .mil
– .net
Domain Names
In the US, InterNIC assigns all of the domain names.
Each country, except the US, has a suffix.
E-mail and Multimedia
An electronic mail message is not limited to text.
Other types of files can be added to mail messages as attachments.
Attachments can be binary files such as a word processed document,
a spreadsheet or a graphic image.
Standalone Web Devices
PC-TV
Network Computer (NC)
PDAs
World Wide Web
Hyperlinked graphics became possible in 1993.
HTTP Protocol invented by Tim Berners-Lee
Uses a markup language called HTML
Web Files
Constructed either in plain or specialized editors.
A coordinated series of pages, properly hosted, is called a web site.
The default page is called the home page.
HTML Components
Java
Developed by Sun
Designed to run on multiple platforms
Hardware and O/S independent
A small Java program is called an Applet
Active X is Microsoft’s equivalent
Common Gateway Interfaces (CGI)
CGI is another way to add interactivity to web sites.
CGI Forms allows servers to capture information remotely.
Many web counters are CGI based.
Other Components
Frames
VRML
IRC
Web Telegraphy
File Transfers
Browsers
Client side software that serves as a web platform.
Reads and displays server based pages.
Extendable through plug ins.
What is a Browser?
A graphical browser allows the user to “point-and-click” to select
hypertext links.
Uses drop-down menus and toolbar buttons to navigate and access resources
on the Internet.
Browsers are Extensible
Browsers often include “helper applications” which are actually software
programs that are needed to display images, hear sounds or run animation
sequences.
These helper applications, or plug ins, are automatically invoked by
the browser when a user selects a link to a resource that requires them.
Make browsers extensible.
Text based Browsers
A text-based browser allows a user to see only text. Graphic elements
are not displayed.
Hypertext links are accessed by using the keyboard.
LYNX is an example of a text-based browser.
Different Browsers
There are many different types of browsers. All perform the same basic
functions (transferring hypertext) but many have specific features that
are unique. Examples of some common browsers are:
Netscape Navigator
Microsoft’s Internet Explorer
Mosaic
E-mail
Most popular web based application. Jan ‘98 Harris Poll indicates that
one in four US adults has e-mail.
E-mail addresses consist of multiple parts.
Last part is the domain name.
Recent figures indicate that 44% of US homes have computers. (UP 11% from
last year.)
What is Electronic Mail
Exchanging information via computer networks
Electronic mail addresses
Client/Server based
Intranets
A network, based upon Internet standards, that exists within a single
organization.
Web Site Issues
Name
Points of Presence
Line Capacity
Maintenance
ISP (Independent Service Provider)
Internet Business Functions
E-mail
Bulletin Boards
Index and Retrieval Services
File Transfer Protocol
Data Push
Internet Merchandising
Dell Computers
Yahoo
Slate
Wall Street Journal
Internet Revenue Sources
Advertising
Direct Marketing
Online Sales
Customer service
Value added Products
Risks
Security Compromises
Viruses
Password cracking
Charge account capture
Getting Hacked
Countermeasures
