COS 125 DAY 8

Agenda Quiz Graded 4 A’s, 6 B’s, 5 C’s, 1 F and 1 no-take Should have been better! Any questions from the quiz? Next Quiz is Feb17 Questions from last Class?? Assignment #2 Due Problems?? Capstone Projects Proposals due Feb 10 Today we will discuss Common Internet Tools and Multimedia on the Internet We will complete the HITW text in the next week and then concentrate on Web Design (Castro text) for the rest of the semester

Objectives Using Common Internet tools How Telnet works How File Compression works How Internet Searching works How agents work How Java, ActiveX, and JavaScript Work Enjoying Entertainment and Multimedia on the Internet How Music and Audio work on the Internet The infamous MP3 file

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 support

Example

How File Compression Works Many file transferred over the internet are compressed Takes a larger files and makes a smaller one from it Some Files can be expanded to original after it is received 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 275KB 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 the work for you Bots “go” the other search engines like google.com and yahoo.com, run the search and “bring” the results back to you

How Internet Agents works “Intelligent” pieces of software that act in your interest Many are invisible to the users Uses Good Searching for info Shopping Web Site Maintenance Bad Distributed Denial of Service attacks 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 Can be in or

JavaScript Interpretive version of JAVA Brings Dynamic capabilities to HTML <!-- (html comment) Lines of script code…. --> Can be in or Jack.htmttp://perleybrook.umfk.maine.edu/samples/Black Jack.htm

ActiveX Controls Only works with Microsoft Browsers 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 HEIGHT=300 CLASSID="CLSID:6BF52A52-394A-11D3-B C04F79FAA6"> … (more PARAM)

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 downloads Audio and video files tend to be very large 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 time Most Popular of these technologies is RealPlayer RealPlayer

Internet Radio Many traditional radio station have started to broadcast over the Internet Larger audience increases ad revenue potential New Internet only Radio stations Netscape radio

How MP3’s are created An MP3 file is a compressed digital music file (about 10-1 compression) Deletes sounds you can’t hear Affects quality

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 violations if you rip copyrighted material and then distribute them This has created a major controversy and brought an end to many music sharing applications 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 your thoughts