 2002 Prentice Hall Internet Inside the Internet and the Web

 2002 Prentice Hall 2 The Internet: A Network of Networks Internet Applications: Communication and Connection Inside the World Wide Web The Evolving Internet Topics “It’s a bit like climbing a mountain. You don’t know how far you’ve come until you stop and look back.” Vint Cerf

 2002 Prentice Hall 3 The Internet is an interconnected network of thousands of networks linking academic, research, government, and commercial institutions. The Internet: A Network of Networks

 2002 Prentice Hall 4 The Internet provides scientists, engineers, educators, students, business people, and others with a variety of services such as:  Electronic mail (send/receive mail messages)  Remote login (Telnet - access to other computers) Internet Services

 2002 Prentice Hall 5 Internet Services  Transferring files (FTP - accessing archives of data)  Newsgroups (Usenet - on- line public discussions)  World Wide Web (a collection of multimedia documents)

 2002 Prentice Hall 6 Counting Connections Today, the Internet connects computers to about every country in the world. However, the Internet is:  growing too fast to measure its growth  too decentralized to quantify  a network with no hard boundaries

 2002 Prentice Hall 7 The language at the heart of the Internet is TCP/IP…  Transmission Control Protocol/Internet Protocol  Allows cross-network communication Internet Protocols

 2002 Prentice Hall 8 Internet Protocols TCP breaks messages into packets  Each packet has all the information needed to travel from network to network  Host systems called Routers determine how to route transmissions

 2002 Prentice Hall 9 Internet Protocols IP is the address for the packets  Each Internet host computer has a unique IP Address  Each address is comprised of four sets of numbers separated by periods, such as

 2002 Prentice Hall 10 Direct (dedicated) Connection  Computer has its own IP address and is attached to a LAN  No need to dial up  Files are stored on your computer  Response time is quick Internet Access Options

 2002 Prentice Hall 11 Internet Access Options Dialup Connections  limited connection using a modem  Full access dial up uses SLIP or PPP via modem Broadband Connections DSL service is newer, faster, and cheaper than ISDN Can share phone line with voice traffic

 2002 Prentice Hall 12 Internet Access Options Cable Modem Connection  allow Internet connections using shared TV cables  can exceed DSL speeds  Carry increased privacy and security risks Satellite Connections  provides connections using DirecTV satellite dishes

 2002 Prentice Hall 13 Internet Access Options Internet Service Providers (ISPs)  local ISPs provide connections through local telephone lines  national ISPs offer connections on a nationwide scale

 2002 Prentice Hall 14 Intranets and Extranets Intranets - self-contained intra-organizational networks designed using the same technology as the Internet Firewalls - used to prevent unauthorized communication and secure sensitive internal data

 2002 Prentice Hall 15 Intranets and Extranets A typical Intranets include:   Newsgroups  File transfer  Web publishing  Other services

 2002 Prentice Hall 16 Intranets and Extranets Extranets: designed for outside use by customers, clients, and business partners Electronic Commerce: business transactions through electronic networks

 2002 Prentice Hall 17 Intranets and Extranets Electronic data interchange (EDI): a decade-old set of specifications for ordering, billing, and paying for parts and services over private networks. Virtual private networks: not subject to the traffic and security problems.

 2002 Prentice Hall 18 The user interface varies depending on which client/server application is being used. UNIX - developed by Bell Labs, allows a timesharing computer to communicate with several other computers or terminals at once. Internet Applications: Communication and Connection

 2002 Prentice Hall 19 Internet Addresses addresses are made up of two parts separated by an sign:  User name  Example: The host is named using DNS (domain name system), which translates IP addresses into a string of names. “Each person on the “Internet” has a unique “address” created by having a squirrel run across a computer keyboard.” Dave Barry

 2002 Prentice Hall 20 Internet Addresses An Internet address includes:  username is the person’s “mailbox”  hostname is the name of the host computer and is followed by one or more domains separated by periods: –host.subdomain.domain –host.domain –host.subdomain.subdomain.domain

 2002 Prentice Hall 21 Internet Addresses Top level domains include: . edu - educational sites .com - commercial sites .gov - government sites .mil - military sites .net - network administration sites .org - nonprofit organizations

 2002 Prentice Hall 22 Internet Addresses Examples: User President whose mail is stored on the host whitehouse in the government domain User hazel_filbert at the server for Lane County, Oregon, k-12 school district

 2002 Prentice Hall 23 on the Internet What appears on the screen depends on the type of Internet connection and mail program you use Eudora is an easy to use software. Outlook and Netscape Communicator are popular software

 2002 Prentice Hall 24 on the Internet Why are free accounts made available?  often offered to attract Web site visitors  available for users of public computers  sensible for those wanting multiple addresses not associated with a workplace

 2002 Prentice Hall 25 on the Internet E Formats include:  ASCII text so they can be viewed with any client program  MIME that can be used to send and receive text with enriched text or HTML (displays text formatting, graphics, and links to Web pages)

 2002 Prentice Hall 26 Mailing Lists and Network News Mailing lists allow you to participate in discussion groups on special-interest topics. Network News are public discussions that you can go in and out as you please.  Messages are posted on virtual bulletin boards (for everyone to read).

 2002 Prentice Hall 27 Real-Time Communication Internet relay chat (IRC) allows several users to chat simultaneously Internet Telephony turns the Internet into a toll- free long-distance telephone service Video teleconferences allow multi-person videoconferences via the Web

 2002 Prentice Hall 28 Real-Time Communication See… Hear … …Type

 2002 Prentice Hall 29 Telnet and FTP Information gathering Telnet - makes remote login possible FTP (file transfer protocol) - allows files to be uploaded and downloaded from remote computers

 2002 Prentice Hall 30 Telnet and FTP Web browsers locate and transfer files without typing commands When you click a Web link to download a file, you’re probably using FTP

 2002 Prentice Hall 31 WWW is a distributed browsing and searching system developed at CERN System was designed to give Internet documents unique addresses HTML language was created for encoding and displaying documents Browser software was built for viewing documents from remote locations Inside the World Wide Web

 2002 Prentice Hall 32 Browsing the Web Web pages are made up of text and images A Web site is a collection of web pages A Home page is the main entry to a Web site A Web browser like Netscape Communicator or Internet Explorer allows you to explore the Web by clicking links Web site Jargon:

 2002 Prentice Hall 33 Browsing the Web Hyperlinks (links) are words or pictures that act as buttons, allowing you to go to another Web page Links are typically underlined or displayed in a different color

 2002 Prentice Hall 34 More on Browsing the Web More Web site Jargon Links allow you to locate information without knowing its exact location (it may move from time to time) Back and Forward buttons let you retrace your steps Bookmarks and Favorites can be set up to mark your favorite Web locations

 2002 Prentice Hall 35 Web Addresses Pronounced Earl…like the name A typical URL looks like this:

 2002 Prentice Hall 36 Web Addresses Protocol for Web pages Dissecting Web Page address: Path to the host Resource Page help/database.html

 2002 Prentice Hall 37 Searching the Web Search engines  produce a list of pages that match a keyword  they are built around a database that catalogs Web locations based on content Directory or Subject Tree  A hierarchical catalog of Web sites Natural Language Search Engines  Allows users to ask for what they want “The ability to ask the right question is more than half the battle of finding the answer.” Thomas J. Watson

 2002 Prentice Hall 38 Search Engines Search engines help find information when you type a query using keywords.

 2002 Prentice Hall 39 Search Engines Directory/subject tree engines offer a menu of subject choices

 2002 Prentice Hall 40 Search Engines Ask questions in a Natural Language Search Engine

 2002 Prentice Hall 41 Portals Portals offer quick and easy access to a variety of services such as , chat,maps, news, shopping, etc. Examples of consumer portals include  Yahoo!, Excite, Lycos, Alta Vista, Netscape Netcenter, Snap  Specialized portals target specific industries and economic sectors

 2002 Prentice Hall 42 From Hypertext to Multimedia Tables Frames Forms Downloadable audio and video Streaming audio and video Real-time live audio or video 3-D environments Typical Web pages can contain:

 2002 Prentice Hall 43 From Hypertext to Multimedia Plug-Ins are software extensions that add new features. Examples include… QuickTime Shockwave/Flash RealPlayer Acrobat

 2002 Prentice Hall 44 Webcasting: Push Technology Client computers pull information  Browsers initiate a request for information Push technology delivers information automatically to the client computer  Up to the minute weather reports  News headlines

 2002 Prentice Hall 45 Publishing on the Web An HTML document includes codes that determines the format, layout, and structure of a Web document HTML (Hypertext Markup Language) HTML is not WYSIWYG

 2002 Prentice Hall 46 Publishing on the Web This text coded as HTML … Appears like this on the screen … Welcome to Computer Confluence Publishing on the Web

 2002 Prentice Hall 47 Publishing on the Web Alternatives to HTML… Programs that convert document format features into HTML codes  Microsoft Word, FileMaker Web authoring programs  HomePage, GoLive, FrontPage

 2002 Prentice Hall 48 Beyond HTML Dynamic HTML: adds more programming power to HTML by allowing code to automatically modify itself under certain circumstances JavaScript: a simple language for enhancing HTML Web pages

 2002 Prentice Hall 49 Beyond HTML WML  Wireless Markup Language helps create Web documents containing stock quotes, phone numbers, and other small nuggets of information XML  Will replace HTML plus provide additional features and extensions VRML  Virtual Reality Modeling Language creates 3-D virtual worlds

 2002 Prentice Hall 50 Beyond HTML Java  A full-featured, cross platform, object-oriented programming language Java applets  Small Java programs that can be automatically downloaded onto your client computer and can run on any platform

 2002 Prentice Hall 51 provides faster network communications for universities and research institutions virtual laboratories, digital libraries, and distance learning applications are being built on Internet 2 Internet2 and the Next Generation Internet The Evolving Internet

 2002 Prentice Hall 52 Filtering software can prevent unwanted and inappropriate content Encryption prevents credit card and forgery Digital cash makes on-line transactions safer Universal access is a problem Ethical and Political Dilemmas Internet Issues

 2002 Prentice Hall 53 A blurring of Web and interpersonal communication applications Internet appliances connected to the Web Continued computer crime and security issues What Next? Electronic Frontier Internet Everywhere: The Invisible Information