The Internet and the World Wide Web

CIT 230

Web Design

History of the Internet• Began as ARPANET in 1950’s

• Funded by the Department of Defense– Purpose was to share resources among DOD contractors and

encourage research in computer networking

• Many academic institutions signed on

• Continued to grow but limited to academic and military uses, not for general public.

• 1989 “Internet” begins to evolve into a common medium with the advent of the Hypertext Transfer Protocol and the birth of the World Wide Wait, er… Web!

1989 - World Wide Web– Tim Berners-Lee and CERN

– Wanted a standardized way in which scientists could communicate with each other

– Codified HTML, based on SGML

– Hyperlinking used.

– Web metaphor emphasizes the intricate interconnectedness of the WWW

– Milestone: 1993-National Center for Supercomputing Applications (NCSA) develops Mosaic.• Marc Andreesen at U of Illinois.

• Later Mosaic becomes Netscape

What is the Internet?• Collection of computer networks

• Meta-network (a network of networks)

• Uses a fixed set of protocols

Backbones

• Transportation analogy– sidewalks, streets, boulevards, highways and

interstates

• Backbone is the internet equivalent of the interstate.

• NAPs: Network Access Points– connect the backbone to regional networks

• San Francisco, San Jose, Chicago, New York, and Washington, D.C. are major backbone access points in the U.S.

Protocols

Internet Protocols (TCP/IP)

• Universal Translator of Networking

– Auto recovery and rerouting built in to the protocol in case of damaged node (Nuclear attack)

– Check/recheck protocol

– Packet switched• breaking down large chunks of data into smaller ones called

packets

• IP moves these packets from node to node.

• Delivery is based on unique IP numbers or addresses

• At delivery, TCP verifies that all the info is intact and reassembles it

Internet Protocols (TCP/IP)

• Transmission Control Protocol / (over) Internet Protocol

• Developed for military

– so hardware communication could occur regardless of manufacturer

Hypertext Transfer Protocol

• Hypertext Transfer Protocol

– HTTP://

– Protocol used to send information (text, graphics, audio, video) across the World Wide Web

– HTTP request sent from users browser to the HTTP server and the response is the web page displayed in the browser

• Hypertext

– Links that make the web interconnected

Extensible Hypertext Markup Language

• XHTML

– a set of codes or commands that control how text and images will appear when it is transferred to a users browser from the server

• Uses tags

– open and close tags

• <h1></h1>

– to mark up the text for formatting

• <h1>This is a Heading</h1>

Web Browsers• Program that sends requests to the HTTP server

• Displays the server’s response

• Examples– Netscape Navigator

– Internet Explorer

• Browser Types– Graphical-text, sound, images-still and moving

• Tend to be slower

• Ability to bookmark sites visited

– Non-graphical, text only browsers• Early development, ASCII text only, Very fast

Web Addresses• Uniform Resource Locator (URL)

– textual address of the data storehouse

• Each part of the URL has a meaning

http://www.byui.edu/academics/index.htm

– http:// -indicates the protocol to be used– www -identifies the web server – byui – identifies the location or company– edu – identifies the location’s domain type – /academics – identifies a subdirectory on the server– index.htm – identifies the specific page being requested.

Domain Name System

• The text version of the IP address

• Each domain name has a unique IP address associated with it

IP Address URI

157.201.10.1 www.byui.edu

136.1.240.21 www.ford.com

Top Level Domains• An indication of the kind of domain

– .edu-educational

– .gov-government

– .com-commercial

– .mil-military

– .net-networking

– .org-nonprofit organization

• Seven new top level domains proposed to be added in November of 2000– .aero-air-transport

– .biz-business

– .coop-cooperatives

– .info-multi purpose

– .museum-museums

– .name-individuals

– .pro-professions

Top Level Domains/2nd Level Domains

• In 2001-.biz, .info and .name were made operational

• Second Level Domain

– The part of the address that actually identifies the organization

• .byui in the previous example

Search Engines and Web Directories

• The card catalogues of the Internet

• Search services offer subject guides to aid in a search– Yahoo! Is really a service with catalogued entries

• Search engines-Lycos, Alta Vista, Info-seek, Google

• Meta-tags used to assist in the search

• Automated-more like a database search.

• Often more current and able to report more minute details of information that may be useful

Search Techniques

• AND

– docs containing both words

• OR

– docs with either or both words

• NOT

– omit specified words

• Boolean logic

• Can use + and – signs as well

FTP

• File Transfer Protocol

• Prior to the web, the way to transfer files over the internet

• Usually UNIX system– odd commands like “get” and “put”

• Telenet – allows users to log on to remote systems and

search directories for files and search databases for information

Usenet

• Electronic newspaper

– Articles posted to a news server

– Read by anyone with a newsreader

• software that allows access to a news group

– Newsgroups are interactive

• readers can respond to articles by posting their own articles

• Forms a discussion thread

– Netiquette rules are enforced

ISPs

• Internet Service Provider– company that allows subscribers to connect to

the internet• Phone, cable, satellites

– Basic services: email, simple web hosting

– ISP selection• local access to avoid long distance charges

• Reliability-little down time and 24 hour access

• Cost varies-shop around

• Connection speed