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18.3-18.4 Internet Services and Steaming Technology on the Internet. Annie 5C (17). What is/are included in Internet services?. World Wide Web (WWW) FTP e-mail remote logon online chat discussion forums Newsgroups. 18.3.1 World Wide Web. Most widely used Internet service
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18.3-18.4 Internet Services and Steaming Technology on the Internet Annie 5C (17)
What is/are included in Internet services? • World Wide Web (WWW) • FTP • e-mail • remote logon • online chat • discussion forums • Newsgroups
18.3.1 World Wide Web • Most widely used Internet service • browsing by IE, Safari, etc. • Transmitted by HTTP • use other relevant application software programs to open the file • e.g. Adobe PDF Reader (PDF file), RealPlayer (video)…
Multimedia Elements on the WWW • usually composed of a large variety of multimedia elements • In graphics • Bitmap graphic file format: BMP, JPG, GIF, PNG • Vector graphic file format: SWF, WMF, EPS • In audio • stored in compressed format • WAV, WMA, MP3, AAC • support audio streaming • In video • WMV, RM, MOV, AVI • all support video streaming
Media Players • Play the audio and video file downloaded from the Internet • Windows Media Player, RealPlayer, QuickTime Player, i Tunes, etc.
Plug-ins • Allow to play audio or video file on web browser • keep the web browser efficient and its file size small • Up-to-date Popular Plug-in application Flash player, Shockwave Player, QuickTime, RealPlayer
18.3.2 File Transfer Protocol • A popular way to transfer files on the Internet • Servers and clients are involved in an FTP transfer
User’s Authentication • Need a username and a password to login • Anonymous FTP • anyone can access the FTP server without login accounts
File Transfer Mode • ASCII • Send plain text • Binary • Transmits the file bit by bit • Reassembles the bit stream into a single file after transfer complete
Command Line Interface • Put • Upload a file from a computer to an FTP server • Get • Download a file from an FTP server to a computer • allow user to manage file transfers in batch
18.3.3 E-mails • Transmit from through mail servers • Run an e-mail program Email address format Francescahi@hotmail.com User ID Mail server domain name
SMTP (Simple Mail Transfer Protocol) • Most popular protocol • Communication btw two mail servers • not allow receiver’s mail server to request e-mails from the sender • Disadvantage: • unable to authenticate email sender • Lead to spam and computer viruses spread by e-mail • transmit of ASCII text-based messages
POP (Post Office Protocol) • most widely used e-mail transmission standard for large organizations • allow user download to their mailbox • can read email anytime
IMAP (Internet Message Access Protocol) • More advanced alternative to POP • Store all of e-mails on the mail server • Advantage: • accept more than one user access the same mail box at the same time • can access the same mail box in different web browser or e-mail program
date subject attachment header body
Digital signature Use to confirm the identity of the sender
18.3.4 Newsgroups • An electronic public message board • Web browser or newsgroups software • Easy to search • Provided by ISP or running a news server
18.3.5 Discussion Forum • Similar as newsgroups • Need to login • The messages contain text, graphics and hyperlinks • Replace newsgroups
18.3.6 Online Chat • One-to-one or one-to-many communicate • Support voice chat with video (webcam) • Online chat programs are yahoo! Messenger, Skype, Windows Live Messenger, etc.
18.3.7 Remote logon • To build up a connection btw a computer and a server • though by LAN, the Internet or public communication media like telephone line
Telnet • 1st network protocol • Use Command line interface • Doesn’t support data encryption • Replaced by Secure Shell (SSH)
18.4 Streaming Technology on the Internet • Not need to download whole of file from web browser before play it • Web browser need plug-in when play the video and audio files
18.4.1 Webcasting • Broadcasting of multimedia use streaming technology over the Internet • used in e-learning and commercial promotions