Chapter 8

 Government and Universities over 30 years  Who’s connected today? ◦ Individuals ◦ Educational institutions ◦ Government ◦ Research ◦ Medical ◦ Businesses ◦ Everyone!

 1969 – US Department of Defense and Rand Corporation  Origins ◦ Cold War – fear that a bomb could demolish computing capabilities ◦ Several computers, geographically dispersed, networked together ◦ Plan – if one computer was disabled, others could carry on using alternative communication routes

 Messages divided into packets  TCP/IP protocol ◦ TCP – does the packeting and reassembling of the message ◦ IP – handles the addressing

 Research computers from universities  Defense contractors  Needed technical expertise to work on Internet

 Mid 1990s  Estimate over 333 million users worldwide  Part of our daily lives  Four factors ◦ TCP/IP standard ◦ Ability to link from site to site ◦ Ease of use of browser ◦ Growth of PC and LANs that can connect

 Unique address of a web page or file on the Internet  Case-sensitive

 Protocol – rules  Communication using links

 Address of the ISP  Domain names are registered  Ongoing fee is paid for each domain name

Represent the purpose of the organization of entity.com.gov.edu.org.net May be a two-letter country code

Directories and file names that specify a particular web page

 Computer with a modem or NIC  Internet service provider (ISP)  Browser  Related software

 Vehicle to access the Internet  Provides ◦ Server computer ◦ Software to connect

 ISP  Members-only services and information  Simple interface with clickable topics  Parent controls

 Used to explore the Internet  Dials the ISP  Display web pages

 Browser display window ◦ Displays contents of web page from each Internet site visited ◦ Screen limits how much of the site you can view at a time. The page can be scrolled using the scroll bar to see its entire contents  Status line – progress of data being transferred and other messages

 Welcome banner on title bar  Browser logo – animation indicates you are in the process of moving to a new site  Hot list ◦ Bookmark ◦ Favorites ◦ Store your favorite URLs  Browser control panel – menus and buttons

 Pull-down menu  Buttons ◦ Convenient shortcuts for commonly used functions ◦ Click button rather than locate command from pull-down menu

 Software that increases the functionality of a browser ◦ Audio-video ◦ Image viewing  Download from web sites  Install  Example ◦ Adobe Acrobat Reader ◦ Shockwave

Java  Write software that is machine independent  Programming language  Dancing icons  Sound clips  Flashing messages  Banners that scroll  Applets – Permits dynamic web pages  Display animations  Receive input  Perform calculations

 Clickable categories in the browser ◦ Sports ◦ Weather ◦ News ◦ Technology ◦ Comic strips  Enter the URL in the address text box and press

 User enters a URL  User computer sends request to the ISP server  ISP server sends request across networks of TCP/IP computers  Destination site is reached  Content is transmitted back to your computer (process in reverse)

Search engine  User specifies a search request  Browser links to Search Engine  Request returns matching pages based upon the Search Engine’s database  Results presented

 Search Engine builds database ◦ Searchable terms ◦ Related web sites  Spider, robot, bot ◦ Follows links across the web ◦ Automatically indexes pages to a database  One word  All words  Pages may be submitted by the owner

 Request same search using different engines yields different results  Databases built independently ◦ Size ◦ Content ◦ Search methodology  Metasearch – atomically puts the same request to several search engines

 Directory  Human involvement  Sites organized by content category  May concentrate on specific content areas  Subjective decisions regarding inclusion and importance  Search Engine  Spider, robot, or bot automatically builds database  Index on a few keywords  Index on all words on web page

 Index only a fraction of the Web  Approximately 20% to 33% of sites  More web pages added daily  Solution ◦ Same request to several search engines ◦ Metasearch

Directories  Yahoo!  NetGuide Metasearch Sites  MetaCrawler  Dogpile Search Engines  AltaVista  Excite  Google  HotBot  Infoseek  Lycos  Northern Light

 Add words  Enclose words in “quotes”  Use Boolean logic  Examples ◦ “World Trade Center” ◦ Jordan AND NOT Michael