Educational Computing

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EducationalComputing
CIS 204January 28-30, 2008

• David Goldschmidt, Ph.D.
• Computer Science
• The College of Saint Rose

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AdditionalPC Hardware
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Networks

• Hierarchical Networks
• Nodes are not equal
• Nodes interconnect instrict pattern
• Single point of failure
• Heterarchical Networks
• Nodes interconnected at random
• No node is more important than another

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The Internet

• Internet is a global decentralized heterarchical
  network made up of many smaller networks
• Information Superhighway
• Originally developed in 1960s as ARPANET
• Advanced Research Projects Agency NETwork
• Continued linked computer availabilityin case of
  nuclear attack
• Use in academia led to e-mail, file transfer,
  Web, etc.

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Internet Backbone Network
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Digital and Analog Communications

• Original telephone infrastructure designed to
  carry analog signals (voice)
• Modems translateanalog to digitaland digital to
  analog
• Digital modems use newer infrastructure
• e.g. fiber-optic cables
• No more analog....

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Local Area Networks

• Local Area Network (LAN) is a networkof machines
  coveringa limited geographicalarea
• Metropolitan AreaNetwork (MAN)covers more
  denselypopulated area

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Wide Area Networks

• Wide Area Network(WAN) covers multiplelocations
• Each location consistsof a LAN or MAN
• LANs and WANs areoften private networks

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The Internet as Global WAN

• The Internet is the worlds largest network
• Links millions of businesses, governments,
  educational institutions, and individuals

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How the Internet Works
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Internet Service Providers

• Internet Service Providers (ISPs) have direct
  connections to (or are part of ) the Internet
• ISPs sell temporary Internet accessto businesses
  and individuals
• Telephone access numbers
• Time Warner Cable
• Digital Subscriber Line (DSL)
• Leased line (e.g. T1, T3) through telephone
  company
• Satellite

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Internet Service Providers
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Internet Service Providers
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Internet Protocols

• What is a protocol ?
• A protocol describes how communicationshould
  take place
• e.g. Roberts Rules of Orders
• Transmit data over the Internet using 2
  protocols
• Transmission Control Protocol (TCP), which
  provides error handling, packet resubmission,
  etc.
• Internet Protocol (IP), which provides
  low-level packet-based communications

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Internet Addresses

• An Internet Addresses identifiesmachines on the
  Internet
• Numeric addresses
• e.g. 66.195.8.30, 128.113.2.9
• Non-numeric addresses
• e.g. www.strose.edu, www.rpi.edu

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Internet Addresses
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Use of the Internet

• How is the Internet used?
• File Transfer Protocol (FTP)
• E-mail
• Interactive Chat / Instant Messaging
• Newsgroups (e.g. USENET)
• Internet Telephony
• Videoconferencing
• World Wide Web

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Billions and Billions Served....
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File Transfer Protocol (FTP)

• FTP is a communications protocol fortransferring
  files between computers
• e.g. Publishing a Web site
• FTP sites on the Internet containdocuments,
  software, images, video, audio, etc.
• ftp//ibiblio.org/pub/docs/books/gutenberg/

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Voice Over IP

• Internet telephony using Voice Over IP (VOIP)

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World Wide Web

• World Wide Web (WWW)
• Invented by Tim Berners-Leein early 1990s while
  at CERN
• Web is decentralized andruns on top of the
  Internet
• Building blocks of the Web
• Uniform Resource Locator (URL)
• HyperText Transfer Protocol (HTTP)
• HyperText Markup Language (HTML)

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Uniform Resource Locators

• Uniform Resource Locator (URL) identifies the
  protocol, domain (machine) name, and file path of
  resource being requested
• http//academic2.strose.edu/math_and_science/golds
  chd

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Domain Name Registration
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HyperText Markup Language

• HyperText Markup Language (HTML) definespage
  layout, fonts, links, text, etc.
• HTML tags describe how Web browsersshould
  display text, images, etc.
• lthtmlgt
• lttitlegtWelcome to My Web Sitelt/titlegt
• ltbody bgColor"gray" text"black"gt
• ltimg src"people.gif" width"184" height"119"gt
• ltpgtWelcome to my cool new Web site.
• lta href"http//www.cnn.com"gtClick here for
  news.lt/agt
• lt/pgt

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Search Engines

• A search engine is an online software application
  that enables users to electronically locate and
  retrieve Web pages
• Keyword-based search
• How does a searchengine know aboutall those
  Web pages?

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Crawling the Web

• How does a search engine know aboutall those
  Web pages?
• Search engine software crawls the Web
• Records everything it sees in giant index
• How do search requests returnresults so quickly?
• LOTS of redundant data on redundanthardware
  distributed across the nationand the world

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Browsing the Web

• We browse the Web using Web browser software
• Internet Explorer
• Firefox
• Safari
• Opera
• Microbrowsers

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Multimedia on the Web

• Web pages incorporate graphics, animation,audio,
  video, etc.
• Software required to view/listen to various
  multimedia

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Graphics on the Web

• Images are available on the Web inmany different
  formats

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Graphics on the Web

• Graphics embedded inWeb pages using HTML

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Saving Images

• After finding an image, right-click on it, then
  select Save Picture As... or Save Image As...

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Audio on the Web

• Audio on the Web may be downloadedor streamed
• Formats includeMP3, WAV, WMV

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Video on the Web

• Like audio, video on the Web may bedownloaded or
  streamed

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Searching for Audio and Video

• Search for audio or video clips using Google
• Add keywords such as audio or video ormp3
  to your search
• Use Google Images to find images
• Use Googles filetype search
• e.g. add filetypewav to your search

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Searching for Audio and Video

• Search for audio using Altavista

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Searching for Audio and Video

• Search for video using YouTube

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Saving Audio and Video Clips

• To save an audio or video clip
• Right-click on the URL link to clip
• Select Save Target As... or Save Link As...
• Streaming audio and video might notsave to your
  own computer
• If not, add URL link as a bookmark or favorite

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Saving a Web Page

• Saving a Web page is tricky because there are
  usually multiple files (HTML, GIF, JPG, etc.)
• Save options
• Save entire Web page
• Save HTML only
• Save text only