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Chapter 10

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  1. Chapter 10 Inside the Internet and the Web

  2. 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 The Internet: A Network of Networks Internet Applications: Communication and Connection Inside the World Wide Web The Evolving Internet

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

  4. Internet Services 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)

  5. Internet Services • Transferring files(FTP - accessing archives of data) • Newsgroups(Usenet - on-line public discussions) • World Wide Web(a collection of multimedia documents)

  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

  7. Internet Protocols The language at the heart of the Internet is TCP/IP… • Transmission Control Protocol/Internet Protocol • Allows cross-network communication

  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

  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

  10. Internet Addresses • 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 e-mail “address” created by having a squirrel run across a computer keyboard.” Dave Barry

  11. 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

  12. Country Top-Level Domains ISO approved country domains • ccTLDs – Country Code Top-Level Domains • Follows ISO 3166-1 • ca -- Canada • jp – Japan • nu -- Niue • uk – United Kingdom • us – United States • tv – Tuvalu • And more

  13. Internet Addresses An Internet address includes: username@hostname.sub.dom • 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

  14. 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

  15. Internet Access Options 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

  16. 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

  17. 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

  18. Internet Access Options • Internet Service Providers (ISPs) • local ISPs provide connections through local telephone lines • national ISPs offer connections on a nationwide scale

  19. Internet Applications:Communication and Connection • The Internet use the client/server model for most Internet applications. • In the client/server model a client program asks for information, and a server program fields the request and provides the requested information from databases and documents.

  20. Internet Applications:Communication and Connection • An email server acts like a local post office for a particular Internet host—a business, an organization, or an ISP. • File serversare common within LANs, but they’re also used to share programs, media files, and other computer data across the Internet.

  21. Internet Applications:Communication and Connection • File transfer protocol (FTP) allows users to download files from remote servers to their computers and to upload files. • File compression saves storage space on disk and saves transmission time when files are transferred through networks.

  22. Internet Applications:Communication and Connection • An application server stores applications- PC office applications, databases, or other applications - and makes them available to client programs that request them. • An application server might be housed at an application service provider (ASP) - a company that manages and delivers application services on a contract basis. • A Web server stores Web pages and sends pages to client Web browsers.

  23. Inside the Web • 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

  24. Inside the Web Web site Jargon: • 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

  25. Inside 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

  26. Inside 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

  27. Web Addresses Pronounced Earl…like the name A typical URL looks like this:

  28. Path to the host http:// help/database.html Web Addresses Protocol for Web pages Dissecting Web Page address: Resource Page

  29. An HTML document includes codes that determines the format, layout, and structure of a Web document Publishing on the Web HTML (Hypertext Markup Language) HTML is not WYSIWYG

  30. Publishing on the Web This text coded as HTML … • <H1>Welcome to Computer Confluence</H1><b>Publishing on the Web</b> Appears like this on the screen …

  31. 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

  32. Tables Frames Forms Downloadable audio and video Streaming audio and video Real-time live audio or video 3-D environments From Hypertext to Multimedia Typical Web pages can contain:

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

  34. 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

  35. 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

  36. 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