Introduction to Computer Science

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Introduction toComputer Science

• The Internet and World Wide Web

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What is the Internet?

• The Internet is a large connection of networks.
• The Internet is not controlled by any agency.
• It contains a variety of services, one of which
  is the World Wide Web.

When I took office, only high energy physicists
had ever heard of what is called the World Wide
WebNow even my cat has its own page. Bill
Clinton, 1996
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ARPANET

• The Internet started as ARPANET in 1969
• US Dept. of Defense
• Allow scientists to share information
• Continue to function if parts were destroyed
• Originally just four main computers housed in
  four different universities

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NSFnet

• National Science Foundation attached its network
  (NSFnet) to the ARPANET in 1986.
• Became known as the Internet
• In 1995, the NSF removed itself as the primary
  manager of the Internet.

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The Internet Backbone

• The Internet backbone handles the bulk of
  Internet traffic.
• The points of connection are National Access
  Points (NAPs), also called point of presence
  (POP).
• An ISP/OSP that has a direct connection to a NAP
  is referred to as first-tier.

Read moreabout theInternetinfrastructure at
http//computer.howstuffworks.com/
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Connecting to the Internet

• "Dial" into an ISP or OSP using a phone modem,
  DSL, cable modem, etc.
• ISPs and OSP have permanent connections to the
  Internet.
• The ISP/OSP provides temporary access to the
  Internet through their connection
• Once connected, you request web pages and other
  services, likee-mail and news groups.

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America Online

• America Online is a very popular online service
  provider.
• In addition to Internet access, AOL users get
  easy-to-use news and entertainment.
• AOL provides a portal service to users, making
  access to different types of information easier.

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Broadband DSL and Cable

• Broadband connections allow more data to travel
  between your computer and the Internet.
• DSL and Cable are the two most common broadband
  choices for home users. Both cost approximately
  40-50 per month.
• DSL (and ISDN) relies on the telephone cables
  managed by your local phone company.
• Cable relies on the Coaxial cables managed by
  your television cable company.

• The number of broadband users in the US nearly
  tripled in the past two and a half years to more
  than 48 million subscribers, according to a
  report by the US Federal Communications
  Commission (FCC).
• http//www.computerweekly.com/
• September 2004

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Dial-up Internet Access

• Dial-up Internet access is still quite popular.
  Although it is a slower type of connection, it
  has some benefits
• Affordable
• Uses standard phone lines
• Adequate for most web surfing and e-mail

• As prices dropped over the past year, broadband
  use at home has surpassed that of dial-up in the
  United States, reaching 53 of residential Web
  users in October, according to Nielsen/NetRatings.
  
• http//yahoo.usatoday.com/
• December 2004

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Connection Speed Trends
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Bright Idea

• Visit http//www.rr.com/rdrun/ and research cable
  internet access.
• What type of internet access is the major
  competitor to cable?
• Visit www.howstuffworks.com to find out how cable
  modems work.
• What type of cable is used for cable internet?
• Why do connections speeds vary with a cable modem?

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World Wide Web

• The Web is a service on the Internet.
• The Web is a collection of web documents on the
  Internet.
• Each web document has an address, called a URL,
  or Uniform Resource Locator.
• We use web browsers to display web pages, just as
  we use Word to display Word documents.

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The W3C

• The World Wide Web Consortium
• Non-profit organization based out of MIT (Mass.
  Institute of Technology)
• W3C members include hundreds of software and
  hardware companies
• Directed by Tim Berners-Lee, founder of the WWW
• Sets standards for many areas of the Internet

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Web Browsers

• Web browsers are applications that read web pages
  (HTML files).
• Microsoft's Internet Explorer is the most common
  browser.
• Others include Netscape Navigator, AOL, Opera,
  and Mozilla.
• New browsers have better support for Web
  standards and greater security.
• You should upgrade to a recent browser when
  possible.

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Microbrowsers

• Handheld browsers have limited graphics
  capabilities
• Some Web sites have alternate version sites for
  users with such devices
• Obviously, web designers need to take into
  consideration the small screen size of handheld
  browsers when adding content and features to a
  site.

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Finding Web Pages

• Enter the domain name for a web site in the
  browser's address bar.
• The browser finds the server and requests the
  default page (usually index.html).
• home.html is another default.
• The server honors the request and the browser
  downloads the web page from the server to your
  computer.
• This whole process can take place in just a few
  seconds.

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Anatomy of a URL
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Downloading

• When you view a Web page, you are viewing a copy
  of that page that has been downloaded to your
  computer.
• You are not looking at the actual page on a Web
  server.
• Pages that are large or contain a lot of
  graphics, download slower and will take longer to
  display.
• Web designers need to find the balance between an
  attractive site and one that downloads quickly.

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Bright Idea

• Visit www.howstuffworks.com and research
  top-level domain names.
• What was the intended purpose of .net and .com?
• Visit www.google.com and do some research.
• What is cybersquatting?
• How much was spent for domain names like
  business.com and altavista.com?

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Web Pages

• Most Web pages are written in a language called
  HTMLHypertext Markup Language.
• Your web browser reads HTML and translates it
  into a user-friendly web page with pictures and
  colored text.
• HTML, it its basic form, controls the markup
  (look) of text.
• Bold, italics, size, color, etc are all
  controlled by HTML
• This word is ltbgtboldlt/bgt, and this word is
  ltigtitalicizedlt/igt.

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HTML is Plain Text

• HTML is a plain text language that can be written
  using any plain text editor.
• Notepad is sufficient for writing even the most
  complex web pages.
• Although programs like MS Word can save files as
  .html, this does not make them an ideal HTML
  editor.
• There are hundreds of free and cheap HTML editors
  with various features available for download.
• There are also popular programs such as FrontPage
  and Dreamweaver that create web pages.

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Basic Web Page
Marks the beginning of the HTML document
Marks the beginning of the body of the page. The
part that people see in their browsers
Tells the browser which version of markup
language is being used
Header information for the Web page. Used by
search engines
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Cascading Stylesheets

• Cascading Style Sheets control the formatting of
  HTML elements
• HTML sets the structure of the document, while
  CSS gives the page color and other
  characteristics
• One css file can be used to format thousands of
  web pages so that they all have a similar look.

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Uplodaing (Publishing)

• After the page is made, upload the page to a Web
  server
• Your ISP may provide server space for you
• Your UCF fees include space on the UCF Web server
• When you store a page/site on someone else's
  server, you have to follow their rules

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File Transfer Protocol

• FTP is the protocol used to upload and download
  files between a local computer and a server
• You will use FTP to send your Web pages to the
  UCF server
• You can FTP within the browser, or
• You can download and install an independent FTP
  program. I use WS_FTP.

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Promoting Your Site

• Promoting your site will get more users there.
  This will increase traffic, and perhaps revenue
• Give your URL to friends/family
• Include your URL in your e-mail signature
• Post your URL in discussion boards and newsgroups
• Submit your URL to a search engine or web
  directory

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Search Engines

• Search Engines continually build a database of
  Web pages by collecting titles, descriptions, and
  page text.
• They use programs called spiders or robots to
  search the Web and collect data.

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A Good Search Engine

• Two key factors make a search engine a good
  search engine.
• The size of its database
• The larger the database, the more likely your
  search results will contain the most recent
  information
• The ranking of results based on searches
• Relevant sites to the users search words must be
  located at the top of the listings. Otherwise,
  users will try a different search engine.

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Using Search Engines

• Learn basic search techniques to improve search
  results
• Use quotation marks for exact phrases.
• Use and signs to include or exclude words.
• Use and and or operators to widen or narrow
  the search.

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Web Directories

• Web directories are lists of web sites organized
  by topic.
• A hierarchical structure is used to make finding
  sits for a particular topic easy.
• Sites in web directories are added by people, so
  the site is really about the topic the user is
  interested in.
• As the programming behind search engines
  improves, the emphasis on web directories
  declines.

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Portal Sites

• Provide a variety of services and links on one
  page
• Want you to make them your home page
• The page that displays when you start your browser

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Web Communities

• Families of related (sometimes loosely) Web sites
• WebReview provides articles and forums for web
  designers.
• iVillage provides info on a wide range of topics
  geared towards women.
• Yahoo Groups maintains web communities for all
  types of groups.

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Online Communications

• E-mail
• The recipient's e-mail address is entered into
  the TO field
• The message is delivered to the appropriate
  mailbox and stored
• The recipient logs into their mail server and
  uses Post Office Protocol (POP) to download the
  message to their local computer
• Newsgroups
• A newsgroup is a collection of threaded
  discussions about a particular topic
• Chatting
• Allows multiple users to communicate in real-time

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Netiquette

• Netiquette is the code of acceptable behavior
  while on the Internet.
• Keep messages brief
• Use clear subjects
• Dont use all caps
• Avoid sarcasm
• Dont write e-mails when upset
• Include your name

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Multimedia

• Combination of elements
• text
• graphics
• sound
• video
• Multimedia can add richness to a Web site, but
  may greatly increase the download time.

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Web Image Formats
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Bright Idea

• Visit www.yahoo.com and research handheld devices
  for communication.
• What is a blackberry?
• What is wi-fi?
• What is bluetooth?
• Visit www.nokia.co to find out about mobile
  browsing.
• What is the benefit of an xhtml browser?
• Are choices extremely limited for xhtml-capable
  phones?

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Animated GIF Images

• An animated gif is a series of still GIF images
  shown in rapid succession to create an animation.
• Movies are like this. A movie is a series of
  still photographs shown one-by-one so that we see
  movement.
• Animated GIFs are fine for simple animations, but
  they can quickly become large (file size) and
  slow down the download process.
• Flash animations can make cool animations with a
  relatively small file size.

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Thumbnail Images

• Small versions of a large image
• Very useful on the Web
• Improves download time for the Web page
• Let Web users know what the image is before they
  decide to wait for a possibly long download.

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Raster (Bitmap) Images

• Lite-Brite displayed images made up of individual
  pegs of color.
• Bitmap images (raster graphics) work the same
  way.
• However, a computer generated bitmap can produce
  millions of different colors and the points of
  light are very small.

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Creating Bitmaps

• We dont use Lite-Brites, to make bitmap images,
  instead, we use computer hardware and software.
• Adobe Photoshop
• Jasc Paint Shop Pro
• Microsoft Paint
• Digital Cameras
• Scanners

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Vector Images

• Vector graphics do not use a bit map structure.
  Instead, they use instructions that describe the
  size, shape, and color of the parts of the image.
• This allows vector images to be resized quite
  easily without affecting quality and without
  affecting filesize.

• Like all vector images, the one above is made up
  of many polygon shapes. These shapes overlap each
  other in layers and together create the boat.

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Audio on the Web

• Waveform is the digital reproduction of a natural
  sound.
• Natural sounds are analogthey are varying
  strengths of a wave.
• A digital sound uses sampling to produce a sound
  similar to the natural sound.

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Audio Formats

• Popular formats include
• WAV
• MP3
• WMA (Windows Media)
• RM (Real Media)
• Some formats can be played from the browser,
  others require a plug-in (supplemental
  application)

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Bright Idea

• Visit www.howstuffworks.com and research how mp3
  files work.
• How does the mp3 format make audio files smaller?
• What is perceptual noise shaping?
• Visit www.apple.com to research the AAC format.
• What are some advantages of AAC over MP3?

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Common Plug-ins

• Plug-ins are often used when browsing the web.
  Some well know apps include
• Acrobat Reader (Adobe)
• Flash Player and Shockwave (Macromedia)
• QuickTime (Apple)
• Real Player (Real)
• Windows Media Player (Microsoft)

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Streaming Media

• Some audio and video can be played while it is
  downloading
• Allows users to start enjoying the media without
  a long wait
• Slow Internet connections can cause the media to
  stop playing intermittently while more of the
  file is downloaded

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Video on the Web

• Video for the Web must be reduced in size and
  quality for fast downloads.
• Most web video will have a grainy look and
  display in a small size.
• Video can be embedded into a web page.
• The user will need a player (plug-in) to watch
  the video.

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E-commerce

• B2B (Business to Business) or B2G
• The book publisher sells the text books to the
  UCF bookstore
• B2C (Business to Consumer)
• The UCF bookstore sells the books to students
• C2C (Consumer to Consumer)
• Students sell the books to other students

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Shopping Carts

• Technology that keeps track of a customers items
  prior to purchase.
• Cookies are often used for this
• Shopping carts allow us to shop around different
  parts of the online store before starting the
  check-out process.
• Some online stores can even remember what we
  put in our shopping carts the previous week or
  month.

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Online Resources

• http//www.google.com/help/basics.html
• http//www.davesite.com/webstation/net-history.sh
  tml
• http//computer.howstuffworks.com/internet-infras
  tructure.htm
• http//www.tucows.com/htmledit95_default.html
• http//searchenginewatch.com/
• http//www.albion.com/netiquette/corerules.html
• http//userguide.website2go.com/p1161.html

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The End

• Make sure you carefully read this chapter after
  going through this presentation on your own and
  in lecture.
• Dont feel like you have to read the whole
  chapter at once. Read five pages at a time, but
  do it.
• Pay special attention to the terms in bold and
  italics. Can you define them without the book?
  Can you explain what they do and how they work?
• Use the review material at the end of the
  chapter. This will help solidify what youve read
  and prepare you for the exams.