COS 125 (PowerPoint) by ert554898


									COS 125

  DAY 8
    Quiz Graded
        9 A’s, 4 B’s, 2 C’s and 2 no-takes
        Any questions from the quiz?
        Next Quiz is Feb17
  Questions from last Class??
  Assignment #2 Due
  Capstone Projects
        Proposals due Feb 10
    Today we will discuss Common Internet Tools and
     Multimedia on the Internet
        We complete the HITW text in a week and then concentrate
         on Web Design (Castro text) for the rest of the semester
How Telnet Works

    Used for remote logins
      Allows you to run commands just as you
       were on that remote computer’s keyboard
      Requires
          Telnet server (remote machine)
          Telnet client (you!)

      Works mostly for UNIX and LINUX
      Windows NT and 2000 has limited server
How File Compression Works
  Many file Transferred over the internet are
  Takes a larger files and makes a smaller one from it
  Some Files Can be expanded to original after it is
        Windows
             .zip
             .arj
        Macs
             .sit
             .hqx
        UNIX
             .gz
             .z
How File Compression Works
    Method one (lossless)
    Look for Redundancies in the file and replace
     with tokens that are smaller than the
     redundant areas
        Works great for text based files
    Example for a text file
        Replace “the” with t1 or T1
        Replace “there” with t2 or T2
        Replace “that” with t3 or T3
        Of course you have to be able to handle an
         occurrence of the token in the original file
             Place after ~ … t1 become ~t1
How File Compression Works

  Method (Lossy)
  Removes detail to reduce file size
  Cannot recreate original
  Usually used for Graphics
      jpeg
      mpeg
Example lossy using jpeg

                      95 KB

How Internet Searching Works

    3 Basic types
        Indexes

        Search Engines
        Meta Search Engines
How Search Engines Work
How Meta-Search Engines Work

    Uses Internet agents
        Software bots (short for robots) that do work
         for you
    Bots “go” the other search engines like and, run the
     search and “bring” the results back to
How Internet Agents works
    “Intelligent” pieces of software that act in your
        Many are invisible to the users
    Uses Good
        Searching for info
        Shopping
        Web Site Maintence
    Bad
        Denial of Service
        Cyber terrorism
Controlling Bots on your web site

    Place a Robots.txt file in your web server
        Bots are to read and follow directions
        The "/robots.txt" file usually contains a record
         looking like this:
                User-agent: *
                Disallow: /cgi-bin/
                Disallow: /tmp/
                Disallow: /~joe/

    Part of the Robots Exclusion Protocol
JAVA Applets
    Creation
        Code
        Compile to byte-code
        Insert into web page
          <applet code=“applet.class” width=200 height=200>
          <param name=“something” value=“somethingnew”>
         Can be in <head></head> or <body></body>

    Interpretive version of JAVA
       Brings Dynamic capabilities to HTML
     <script language=“JavaScript”>
     <!-- (html comment)
     Lines of script code….
    Can be in <head></head> or <body></body> Jack.htm
ActiveX Controls

  Only works with Microsoft Browser on
   Microsoft operating systems
  Allows HTML code to use a application
   on the PC through Microsoft COM
   (Component Object Model) model
  Require the CLASSID for the application
   you wish to use
Using the Microsoft Media Player
through ActiveX
 <OBJECT ID="WindowsMediaPlayer1" WIDTH=400
   <PARAM NAME="URL" VALUE="roya.mpeg">
   <PARAM NAME="rate" VALUE="1">
   … (more PARAM)
  <PARAM NAME="_cy" VALUE="10583">
Multimedia and the Internet
    Everything that has been done with audio and video can be
     replicated on the Internet
         Radio
         TV
         Film
    The Internet brings more “life” to audio and video
         Interactivity
         Combining multiple formats together
         Virtual reality
         First person simulations
    Downside
         Need lots of bandwidth
         Allows for dysfunctional social behaviors
              Escapism
              Social Withdrawal
Music and Audio on the Internet
    Download audio files and play them
        .wav
        .mp3
        .wma
        .au
    Most browser can play most audio files
        Plug-ins
        Helper applications
    Popular Audio Players
        Winamp
        Windows Media Player
        Realplayer
Problems with Multimedia files
    Audio and video files tend to be very
      Slow to download
      Can take longer to download the file than it
       takes to play the files,especially over a dial
       up connection
      One way to over come this problem is to
       “stream” the files
            Streaming Demo
Video and Audio Streaming

    Streaming is playing and downloading a
     file at the same time
        As soon as enough of the file has been
         downloaded..the applications will begin to
         pay the file amd hope the rest gets there in
    Most Popular of these technologies is
Internet Radio

    Many traditional radio station have
     started to broadcast over the Internet
      Larger audience increases ad revenue

    New Internet only Radio stations
      Netscape radio
How MP3’s are created

  An MP3 file is a compressed digtal
   music file (about 10-1 compression)
  Deletes sounds you can’t here
The MP3 Cycle
Making your own MP3

    You need a MP3 Ripper
        Compresses the digital audio (usually a CD
         audio track) and encodes in MP3 format
  There are issues with copyright violation
   if you rip copyrighted material and then
   distribute them
  This has created a major controversy
   and brought an end to many music
   sharing applications s like Napster
For next class

  Read through to Chap 40 (page 251)
  Think about Free Music File Sharing. Is it
      Legal?
      Moral?

      Ethical?

      Be prepared to define you thoughts

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