COS 125 by fjzhangweiqun


									COS 125

   Assignment #2 Corrected
       10 A’s

   Capstone Projects Proposals (over) Due
       Missing 6 proposals
   Today we will discuss Multimedia on the Internet and
    Begin Shopping and Doing Business on the Internet
       We complete the HITW text this week and then
        concentrate on Web Design (Castro text) for the rest of
        the semester
           Assignments will get harder as the course progresses

   Next Quiz is Feb 26 over the rest of HITW test
       20 M/C, 4 Short essays, One extra Credit
Free Music File Sharing

   Is it
       Legal?
       Moral?
       Ethical?
       Define your thoughts
Music & File Sharing
   Hottest applications this decade
   Forced the music Industry to “rethink” its
    distribution channels
       The problem
            People buy CD and rip them to MP3s
                 Not a Problem
            People place these MP3 in a shareable locations
                 Not a Problem
            Other people copy the shared out MP3s
                 Copyright violation!
                 Buying a CD allows personal use and not redistribution
            Who’s at fault?.. The person who made the MP3’s
             or the person that copied them?
                 Open debate
Apple iPod response

   Apple recognized a need for digital
       No easy & legal way to obtain that
       Developed a really easy to use music
        appliance  iPod
       Create iTunes to load music onto iPods
   iPod lead to podcasting

   Digital jukebox for PCs
   Music source
       iTunes Store (DRM protected)
       Personal owned CD’s
   Listen to music on PCs or download
    to iPod
   Can create CD’s (unless DRM
How KAZAA Works

   KAZAA has two types of Computers
       PC’s that share out files
       SuperNodes that keep directories of
        “who has what”
       Any computer that has a Broadband
        connection can be a Supernode
How KAZAA works

   After you download KAZAA and
       You computer broadcasts looking for
       When it find one it uploads your file
       When you look for a specific file you “query”
        the supernode
       The supernodes tells your computer where you
        can find the file on someone's else computer
       You download the file from the other computer
Kazaa Licenses
   You agree not to use the Software to:
    2.1 Transmit or communicate any data that is unlawful, harmful, threatening, abusive,
    harassing, defamatory, vulgar, obscene, invasive of another's privacy, hateful, or
    racially, ethnically or otherwise objectionable;
    2.2 Harm minors in any way;
    2.3 Impersonate any person or entity or falsely state or otherwise misrepresent your
    affiliation with a person or entity;
    2.4 Forge headers or otherwise manipulate identifiers in order to disguise the origin of
    any data transmitted to other users;
    2.5 Transmit, access or communicate any data that you do not have a right to
    transmit under any law or under contractual or fiduciary relationships (such as
    inside information, proprietary and confidential information learned or disclosed as part
    of employment relationships or under non-disclosure agreements);
    2.6 Transmit, access or communicate any data that infringes any patent,
    trademark, trade secret, copyright or other proprietary rights of any party;
    2.7 Transmit or communicate any data that contains software viruses or any
    other computer code, files or programs designed to interrupt, destroy or limit
    the functionality of any computer software or hardware or
    telecommunications equipment;
                  Index Server            File List
                                         List of
   Uploads List
 Of Available Files
 When Connects             2.
                                        From All
                      Search Query
                                     Current Clients
                                           Large P2P

Client PC                     Client PC                Client PC
How BitTorrent Works
   Downloads from more than one source (a
   A user searches for a particular Video or
    Music CD
       Freely available torrent clients
       Get a small “pointer file”
          Address of tracker server
          Information about all the “bits” of the
       Tracker server informs client about the seed
        computers that have knowledge of all the
        parts of the file
 Bit torrent technology
How Video on the Internet Works

   Three methods of delivery
       Multicast (MBone)
       Streaming Video
       Videoconference
            Requires webCam
How Streaming Video Works

   Same as Streaming Audio
   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 play the file and hope the rest
     gets there in time
    Demo from Learn The Net
Video Conferencing
   Many Software solutions for Video
   NetMeeting built into
       Windows 2000
       Windows XP
       Just add
         WebCam
         Microphone

   Works on H.323

   Small Digital cameras
       Best ones work on USB 2.0
       Avoid Parallel port versions
   Used to create videos
Multicast and MBone
   Video files and streams tend to be
    very large
       What happens when thousands of
        people want to see the same video at
        the same time
       Video 100MB * 10,000 viewers
            We need 1000 GB of band width at the
             source of the video
       A better way?
            Think of how cable TV works
   What would happen if the server sent one
    copy of the video file to each location that
    had users and let the routers make
    individual copies for each user
   Each multicast router copies the files and
    send copies to each network that requires
    the file
   Source only has to send one file
       Multicast routers handle the individual users
Unicast ---------------------Multicast
Virtual Reality

   3-D illusion in 2-D space
   Requires special plug-ins or browser
How VRML works
   VRML code is plain (ASCII) text.
   The code describes object(s) attributes, such as, geometry,
    size, color, textures and location within the virtual world.
   In order to view VRML scenes you must have a VRML capable
    browser. Usually an add-on plug-in or a browser designed for
   When a user encounters VRML on a website the browser
    receives instructions from the server on the other end.
   The server sends VRML code to the user's browser. The VRML
    viewer then interprets the instructions and displays the
   Downloaded VRML text files are interpreted locally, on the
    users computer, by the VRML player and rendered in real-
    time by the CPU.
   The files range in size from under 100 kb to several
    megabytes, so bandwidth directly effects download or access
   Once the world is loaded, the user's experience is dictated by
    the CPU performance. High performance processors allow
    faster and smoother navigation through VRML world
Animations on the Web
   Animation are still created as they always
       Series of pictures that are slightly different
        that are displayed one after another
   Different ways of accomplishing this
    technique on the web
       Client Pull
       Server Push
       Animated Gifs
       Macromedia Shockwave
       Macromedia Flash
Client Pull

   The clients loads the first picture in
    the series and sets a timer
       Then load the second
       Then the third
   Uses special “Meta” refresh tag in
   Very Slow
   example
Server Push

   Web Server pushes new pictures in
    the series to the browser
       Only works in Netscape
       Requires special server side
   Nobody uses it any more
Animated Gifs
   Probably the easiest way to create an
       Lots of free tools available

   We will be using Paint Shop Pro in this
   Example
   Macromedia Software
       Shockwave
       Flash
   These are classes all by themselves
   Examples

                 Picture Source:

   Intranets are private Internets
    limited to a specific organizational
   Has many of the same applications
    as the Internet
   Segmented away from the Internet
    by firewalls
       We’ll discuss firewalls later
       May allow VPN access through firewalls
Intranets applications
   Internal e-mail
   Databases
   Scheduling
   Collaboration tools
       Groupware
       Chat & IM
       Whiteboards
       Videoconferencing
       Document management

   Virtual Private Networks
   Encrypted traffic that travels in
    “tunnels” between encryption &
    decryption devices
Shopping on the Internet

   Shopping on the Internet involves
    many technologies
       Databases
       Encryption
       Cookies
       eWallets
       HTML
How Online Shopping works
   Demo from Learn The Net
   Steps
       Find the product you want
            Database and search technologies
       Fill out order form with Personal Info and Credit Card info
            Data is encrypted and sent to eMerchant
       eMerchant verifies Credit Card and info electronically
            SET and other protocols
       eMerchant confirms orders to customer
            By e-mail
       EMerchant contacts distribution center to ship product
            UPS, FedEx or USPS
How Cookies Work

   A cookie is a small text file written
    by a web server to your hard drive
       Look for a cookies directory on your PC
   The web server that wrote the
    cookie can read and or modify the
    cookie (so can sophisticated
   They are used to track users
   Advantages                      Cookie from my PC

       Allows you to auto-login to site
       Keeps you from entering your info all the time
       Helps eMerchant do business
   Disadvantage
       Cookies stay on PC and don’t follow the user
       Spy-ware! (discuss later)
       Other people can see your info
Online shopping carts
   Requires login to site
       Data store in Database at the
        eMerchant site
       EMerchant creates a cookie on your PC
   As you add stuff to you cart, your
    cookie gets modified
   When you are ready to “check out”
    you cookie is read and then erased
    after you have placed the order
How Electronic Wallets Work
   Online equivalent of a real wallet
       Store information
          Personal
          Credit Cards

       Encrypted
   When you need info on online you
    “open” your wallet and provide the
   Not widely supported
Online auctions

   One of the mostly successful
    eCommerce business models
   Works like a regular auctions except
    everything is done Virtually
   Online Auction Guide

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