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Lecture 03 Going Online Topics Basics Connecting to the Internet World Wide Web Internet...
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Transcript of Lecture 03 Going Online Topics Basics Connecting to the Internet World Wide Web Internet...
Lecture 03 Going Online
Topics Basics Connecting to the Internet World Wide Web Internet Applications Internet Ethics
© 2005 Prentice-Hall, Inc. Slide 1
Basics
Internet: worldwide collection of interconnected networks; Computers are no longer lonely ARPANET (1969): network for scientists that evolved into the Internet Internet backbone: major communications lines and nodes to which thousands of hosts are connected
© 2005 Prentice-Hall, Inc. Slide 2
Basics
No one group controls the Internet, but some organizations coordinate Internet activitiesThe Internet Society to assure the open development, evolution, and use of the InternetICANN (Internet Corporation for Assigned Names and Numbers): responsible for coordinating the assignment and allocation of domain names and internet addressesW3C (World Wide Web Consortium): create and maintain technical specification to keep pace with changing technologies used on the Internet
© 2005 Prentice-Hall, Inc. Slide 3
Connecting to the Internet
Bandwidth: amount of information that can be sent over the channel, in bps (bits per second)Broadband – high bandwidthNarrowband – low bandwidth
© 2005 Prentice-Hall, Inc. Slide 5
Connecting to the Internet
Narrowband Dialup service
Phone line Modem 56 Kbps
© 2005 Prentice-Hall, Inc. Slide 8
Connecting to the Internet
Broadband Cable
TV cableLAN PC card Cable modem1 M~10 Mbps
DSL (Digital Subscriber Line)Phone lineLAN PC card ADSL modemUpstream rate: 128Kbps~1.5MbpsDownstream rate: 1.5M~9Mbps
© 2005 Prentice-Hall, Inc. Slide 9
Connecting to the Internet
Broadband (cont)Satellite
Satellite discSatellite modemLAN PC cardUpstream rate:56Kbps~1.5MbpsDownstream rate: 400Kbps~1.5MbpsLatency – time lag in communication
Wireless AP (Access Points) Wireless LAN PC card Wi-Fi (Wireless Fidelity) standard
Wireless-B (IEEE 802.11b)/11Mbps/300ftWireless-A (IEEE 802.11b)/54Mbps/50ftWireless-G (IEEE 802.11g)/54Mbps/Far better than A
© 2005 Prentice-Hall, Inc. Slide 9
Connecting to the Internet
ISP (Internet service provider) Communication software (Dialup/ DSL) Hinet/ Seednet
Information service gateway Communication software (link to the information network of AOL) user ID and password AOL (America OnLine)/ MSN
Direct LAN connection T-1 line (1.544Mbps) T-3 line (44.736Mbps)
© 2005 Prentice-Hall, Inc. Slide 10
Connecting to the InternetProtocol TCP/IP (Transmission Control Protocol/Internet Protocol)
Protocol: set of rules for how computers communicate, defining message format and interaction patterns Packet: the part of a message that contains the data and the address the message is being sent to Packet switching
TCP dividing files into packets IP routing each packet to destination
© 2005 Prentice-Hall, Inc. Slide 11
Connecting to the Internet
IP (Internet Protocol) addressIdentify each device attached to the Internet by numbersFour numbers, each 0~255, separated by periods, e.g., 206.28.104.10
Fixed vs. Dynamic IP address Domain names
Identify each device attached to the Internet by symbols, e.g., ailab2.et.ntust.edu.twtop-level domains: denote affiliation
.com/.eduDNS (Domain name system)
Translate domain names to IP addresses
© 2005 Prentice-Hall, Inc. Slide 12
Connecting to the Internet
URL (Uniform Resource Locator)Identify each resource on the Internet, e.g., ftp://ailab2.et.ntust.edu.tw/www/InfoTech/Lecture01.pptFour parts
access method: ftpDomain name: ailab2.et.ntust.edu.twPath name: www/InfoTechResouce: Lecture01.ppt
© 2005 Prentice-Hall, Inc. Slide 12
Connecting to the Internet
Client program runs on user’s computer
Internet browser/ FTPPro Server program – runs on server computer
© 2005 Prentice-Hall, Inc. Slide 14
Connecting to the Internet
More devices to connect to the Internet
televisions/ Freezer video game consoles PDA/ cellular phones Internet appliances
A specific device to go online at anytime, any place
© 2005 Prentice-Hall, Inc. Slide 13
World Wide Web
WWW, the Web (World Wide Web)Website
Web serversContaining webpages and server programsHome page – first page you see at a site
WebpageA document containing multimedia data and hyperlinksHyperlinks – allow user to click on an icon and be taken to other resources on the InternetDocument structure is specified by HTML/ XML/…
© 2005 Prentice-Hall, Inc. Slide 17
World Wide Web
WWW, the Web (World Wide Web)
BrowsersA client program which interprets a webpage and interacts with the Web serverIE/ Netscape/ KKman/ Mozilla Firefox
HTTP (Hypertext Transfer Protocol)
A protocol for client and server programs to communicate © 2005 Prentice-Hall, Inc. Slide 17
World Wide Web
HTML (HyperText Markup Language)
A language to format a webpage using paired tags, e.g., <i> </i>; <a> </a>Define how each multimedia component in a webpage is displayed
XML (eXtensible Markup Language)
A meta-language to define the language for formatting a webpage© 2005 Prentice-Hall, Inc. Slide 12
World Wide Web
Browser Plug-insSoftware modules that are integrated into a browser to add flexibilityAnimation/ multimedia displays
Applets or ActiveX controlsStreaming audio and video
Media is presented continuously instead of being downloaded
Java RTE/ Flash player/ Window Media Player/ RealJukebox/ QuickTime/iPIX Movies/ Acrobat Reader/ Liquid Player
© 2005 Prentice-Hall, Inc. Slide 18
World Wide Web
Common operations of Browser Back: go to previous page Forward: go to next page Stop: ends transmission Refresh: reload Web page Bookmarks (Favorites): have browser remember favorite sites Location bar: where user enters URL
© 2005 Prentice-Hall, Inc. Slide 21
World Wide Web
Finding information on the Web Browsing: just looking around portals
Portal: a site that provides a number of services Classified Index databaseYahoo/ Yam/ Excite..
Searching: trying to find specific information by using search engines
Search Engine: a program that goes to the Internet or within a Website to search for webpages users needGoogle/ Yahoo/ Excite/ MSN/Hotbot/ Ask Jeeves/ Infoseek/ AltaVista/ Metacrawler/
© 2005 Prentice-Hall, Inc. Slide 26
World Wide Web
Tips for searching the Net Read the rules for each search engine Try multiple search engines Follow hyperlinks Choose search terms carefully Be persistent Use FAQ (Frequently Asked Questions)
lists answers to questions asked often at a particular site
© 2005 Prentice-Hall, Inc. Slide 29
Internet Applications
Resource retrieval WWW
Web server user-friendly multimedia documents hyperlinks interactive frames Integration of Internet applications, e.g., FTP, email, ..
© 2005 Prentice-Hall, Inc. Slide 32
Internet Applications
Resource retrieval (cont)FTP (File Transfer Protocol)
FTP serverEasily download/upload filesAnonymous FTP sites
JukeboxHelp a client program to gather mp3 and other audio files from Internet music resources
© 2005 Prentice-Hall, Inc. Slide 33
Internet Applications
Communication E-mail
e-mail server file attachments
Newsgroups Mailing lists or listservs
push technology – information is delivered automatically from the server to client programs
ChatInstant messaging (Whiteboarding)
© 2005 Prentice-Hall, Inc. Slide 34
Internet Ethics
Netiquette Using all capital letters is considered SHOUTING Never send unsolicited e-mail (spam) Consider your audience when forwarding Internet content
© 2005 Prentice-Hall, Inc. Slide 36
Internet Ethics
Netiquette (cont) Never reveal others’ personal information Be patient with people who are justgetting online (newbies) Don’t comment on others’ spelling,grammar, or punctuation
© 2005 Prentice-Hall, Inc. Slide 37
Internet Ethics
Netiquette (cont) Keep private communications private Consider e-mail attachment sizebefore sending to someone (using dialup) Confirm virus warnings before forwarding Use an anti-virus program
© 2005 Prentice-Hall, Inc. Slide 38