Transcript internet
INTERNET A collection of networks History ARPANet – developed for security of sending in case of a nuclear attack IDEA – the system would not go down Characteristics Not all units directly connected Client/server type of connectivity Makes use of a router Makes use of a gateway Information transmitted by packets What is the first step in becoming an Internet user? Subscribe to an ISP Internet service provider What am I buying? Three basic services telnet FTP email Definitions Telnet – allows communication with remote computers FTP – file transfer protocol Email – communication software You also get 2 protocols: 1. IP 2. TCP Definitions IP – internet protocol refers to type of topology defines a packet to be 1500 bytes does the routing TCP – transmission control proto Transmission will be through a sequence of packets Assembles and disassembles the packets What else do I get? A Browser Software that is used to explore the Internet Can I get anything else? A Plug-In Software that adds to the browser (video) Additional software – SEARCH ENGINE USES A SPIDER??? Software that builds a database of searchable terms Search Engines Vary InfoSeek – searches newsgroups, FAQs, and email addresses in addition to Web sites AltaVista – indexes every word on a page Excite – provides related hints and extra content Google – results ranked by algorithm based on number of links from other pages Lycos – numerous search options/a comprehensive directory HotBot – excels at finding current news/fast Northern Light – group results by subject, type, source, and language Two with the Broadest Coverage Directories YAHOO Sites are organized by content category Metasearch Engines MetaCrawler Dogpile Software that searches the search engines Boolean Logic Narrowing the search Do I have access to the World Wide Web? And you might not You might World Wide Web (WWW) provides a uniform type of access to all Internet services A type of GUI (graphical user interface) Characterized by HTML HTML hypertext markup language Hypertext – allows access to other addresses by pointing and clicking on a picture or text The address is attached through the code of the hypertext format <A HREF = www.whitehouse.gov main menu </A> main menu is the text which should be highlighted to access this address Other HTML symbols <HTML> </HTML> Goes at the beginning of the document and at the end to define it as using hypertext protocol <HEAD> </HEAD> Beginning and end of heading section <B> </B> Beginning and end of bold text If a website does not use the World Wide Web, it still has the same services. Access is no longer through graphics. Access is now done through a series of menu options. Important point. JAVA A programming that allows permits dynamic Web pages Allows the following: dancing icons sound clips flashing messages scrolling banners applets – programs that provide code for these features ActiveX controls – Microsoft feature that provides the same features WARNINGS Must have a browser that is capable of running these applets Applets present some security risks. Disadvantage Not as user friendly. Advantage Downloading time will be less. Not downloading pictures, colors, etc. Internet Addresses URL’s (uniform resource locators) Each is an IP number. www.whitehouse.gov GOV EDU COM NET ORG MIL UK DE Country designators BIZ PRO INFO NAME COOP MUSEUM AERO GOV EDU COM NET ORG MIL NETWORK of DOMAINS Creates A MESH TOPOLOGY WWW.WHITEHOUSE.MAJORDOMO.GOV Individual computer Defines use of hypertext protocol DOMAIN Subdivision of the individual computer http://www.fdu.edu/pwagner.html Individual computer Defines use of hypertext protocol DOMAIN File (web page) to get Wireless Internet Access Types of devices Text pagers PDAs – personal digital assistants Pocket computers Web enabled cellular phones Wireless Internet Access Additional hardware/software needed: Account with wireless access service provider Cellular modem card or adapter Problem – limited display area Wireless Application Protocol – used by providers to convert Web pages to capabilities of hand held devices