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Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 1
Topic 1 - Introduction to the Internet, Web, and Web browsers
Outline1 History of the Internet2 The Internet today3 Host Machines and Host Names4 The Client/Server Software Model5 Personal Computing6 The World Wide Web 7 Web Browsers8 Searching the Internet
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 2
History of the Internet ARPAnet
Implemented in late 1960’s by ARPA (Advanced Research Projects Agency of DoD)
Networked computer systems of a dozen universities and institutions with 56Kbps communications lines
Grandparent of today’s Internet Intended to allow computers to be shared Became clear that key benefit was allowing
fast communication between researchers – electronic-mail (email)
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 3
History of the Internet
ARPA’s goals Allow multiple users to send and receive info
at same time Network operated packet switching
technique Digital data sent in small packages called packets Packets contained data, address info, error-control
info and sequencing info Greatly reduced transmission costs of dedicated
communications lines Network designed to be operated without
centralized control If portion of network fails, remaining portions still
able to route packets
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 4
History of the Internet
Transmission Control Protocol (TCP) Name of protocols for communicating over
ARPAnet Ensured that messages were properly routed
and that they arrived intact Organizations implemented own networks
Used both for intra-organization and communication
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 5
History of the Internet
Huge variety of networking hardware and software appeared ARPA achieved inter-communication between all
platforms with development of the IP Internetworking Protocol Current architecture of Internet
Combined set of protocols called TCP/IP The Internet
Limited to universities and research institutions Military became big user Next, government decided to access Internet for
commercial purposes
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 6
History of the Internet
Internet traffic grew Businesses spent heavily to improve Internet
Better service their clients Fierce competition among communications
carriers and hardware and software suppliers Result
Bandwidth (info carrying capacity) of Internet increased tremendously
Costs plummeted
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 7
The Internet is a network of networks that are spread all over the world
Networks that are geographically close are called Local Area Networks (LANs)
Often in the same building The university’s network is a prime example
The Internet is a largely heterarchical network containing many individual LANs
A heterarchical network contains many nodes that are interconnected.
A hierarchical network contains a tree-like structure where some nodes are superior to others.
The Internet today
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 8
The Internet today
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 9
A characteristic of a heterarchical network is that it is a robust network.
If some nodes are removed, data can still be sent between nodes
Hierarchical networks do not lend themselves to robustness
The Internet also has dynamic routing, where the route of the data is determined at the time of transmission based on current network conditions.
The Internet today
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 10
The Internet today
How big is the Internet? Number of networks Number of servers Number of domain hosts Number of (indexed) web pages / web sites Usage statistics Number of countries Amount of stored information
What about the Deep Web?
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 11
Each computer on the Internet is a host machine.
Each computer has a unique Internet Protocol (IP) address, such as 124.110.24.1 Some computers have a permanent IP address Some computers borrow an IP address while
they are connected to the Internet An IP address is not human-friendly
Host Machines and Host Names
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 12
The IP address for most host machines are mapped to a Domain Name Service (DNS) address in order to be more people-friendly
The DNS address consists of a host name followed by a domain name
Example DNS Address: mail.yahoo.com Host Name is: mail Domain Name is: yahoo.com
Host Machines and Host Names
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 13
Each domain name consists of: Institutional site name Top Level Domain name (TLD)
Example: cse.fau.edu cse.fau is the Dept. of Computer Science and
Engineering at Florida Atlantic University edu refers to an educational site
Host Machines and Host Names
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 14
Examples of TLDs include: .com a commercial organization .edu a US educational site .net a network site .au Australia .fr France .hk Hong Kong .es Spain ... (many others)
Host Machines and Host Names
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 15
New TLDs have been added as the original set became overloaded
While each machine has a unique IP address, it can have multiple DNS addresses (called aliases)
Anyone can register a DNS address When you type in a DNS address, a
domain name server translates it into an IP address.
Host Machines and Host Names
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 16
Clients and servers are host machines A client is the host machine that requests
information from the server The server is a resource that provides a
service for (many) clients The client/server interaction is the
foundation for all Internet communication
The Client/Server Software Model
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 17
The Client/Server Software Model
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 18
Some companies use servers that do not need to be installed on the client to supply commercial software to clients
Application Service Providers (ASPs) provide software through subscriptions
The software is “rented” with this arrangement
The Client/Server Software Model
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 19
Personal Computing
IBM 1981, introduced IBM Personal Computer Made personal computing legitimate in
business, industry and government organizations
Computers were “stand-alone” units Info only shared between computers through
exchange of discs Machines could be linked
Over telephone lines Over Local Area Networks (LANs)
Led to distributed computing
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 20
Personal Computing
Computers today As powerful as million dollar machines from 20 years
ago Workstations
Most powerful desktops today Provide users with enormous capabilities
Information easily shared over networks Networks controlled by servers
Common programs and data used by client computers Popular operating systems
UNIX, MacOS, Windows XP, Linux Portable devices (PDAs, tablet PCs, cell phones) with
great computing power
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 21
The World Wide Web (WWW or Web) has become a popular means of accessing information and services.
The Web allows computer users to easily locate and view multimedia-based documents.
Introduced in 1990 by Tim Berners-Lee The Web and the Internet (Net) are not the
same. A Web browser is the software necessary to view
information. Some browsers are integrated into other
software, such as an email client.
The World Wide Web
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 22
Navigating the Web only takes a few commands.
The information in the Web is organized as hypertext, graphics, video, and sound
The text in a Web page may contain hyperlinks that, if clicked, allows you to view related information on other Web pages.
You control where you go and what information you see via these hyperlinks
The World Wide Web
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 23
A Web page is a document on the Web that you view through your Web browser
The act of reading Web pages and clicking on hyperlinks is called browsing
Browsing can be seen as a way of exploring
Each Web page has a unique address called a Uniform Resource Locator (URL) that you can use to jump directly to it
The World Wide Web
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 24
The World Wide Web
World Wide Web Consortium (W3C) (www.w3.org) Founded in 1994 by Tim Berners-Lee
Devoted to developing non-proprietary and interoperable technologies for the World Wide Web and making the Web universally accessible
Standardization W3C Recommendations: technologies standardized by
W3C include Extensible HyperText Markup Language (XHTML),
Cascading Style Sheets (CSS) and the Extensible Markup Language (XML)
Document must pass through Working Draft, Candidate Recommendation and Proposed Recommendation phases before considered for W3C Recommendation
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 25
Web browsers Popular browsers (and market share as of Jan 2005)
(Source: http://www.w3schools.com/browsers/browsers_stats.asp)
Microsoft’s Internet Explorer: 69.9% Firefox: 18.7% Mozilla: 4.1 % Opera: 2.1% Netscape: 1.4 % Others (Safari, Camino, Epiphany, iRider, and several others...):
3.8 % Browser portability
Great challenge Great diversity of client browsers in use Many different platforms also in use
Difficult to Know capabilities and features of all browsers and platforms in
use Find correct mix between absolute portability, complexity and
usability of features
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 26
Web browsers Different browsers can be distinguished from each other
by the features they support. Modern browsers and web pages tend to use many features and techniques that did not exist in the early days of the web.
Some of contemporary browsers’ elements and features: ActiveX Ad filtering Autocompletion of URLs and form data Bookmarks for keeping track of frequently accessed
locations Cascading Style Sheets Cookies which enable a website to track a returning user Caching of web content Digital certificates Download management DHTML Embedded images using established graphics file formats
such as GIF, PNG, JPEG, SVG Flash
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 27
Web browsers Browser elements and features (cont’d)
Favicons Fonts, size, color Forms for submitting information Frames and IFrames History of recently visited pages HTTPS Integration with other desktop applications Offline browsing of cached content Java applet JavaScript for dynamic content Plug-ins Session management Tabbed browsing Tables XHTML and XML
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 28
Searching the Internet Search engines
Web sites that sort through by keywords and categories
Google (www.google.com) The rest
Store information in databases Returns list of sites as hyperlinks
Meta-search engines Do not maintain databases Aggregate results from multiple search
engines Meta Crawler (http://www.metacrawler.com/)
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 29
Fun Assignment (FA) # 1 Select a browser of your preference and:
Explore all its menus and options Customize it to your needs and preferences Compare against other browsers Use it to explore Google
Fall 2005 - Introduction to Internet Computing Copyright © 2005 Dr. Oge Marques 30
Links of the day Blackboard @ FAU:
http://blackboard.fau.edu/ Wikipedia, the free encyclopedia:
http://en.wikipedia.org/wiki/Web_browser Google:
http://www.google.com/
Contribute your own favorite links via Bb’s Discussion Board (“Useful links” forum)