 2002 Prentice Hall Chapter 10 Inside the Internet and the Web

 2002 Prentice Hall 2 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 3 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 4 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 5 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 6 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 7 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 8 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 9 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 “address” created by having a squirrel run across a computer keyboard.” Dave Barry

 2002 Prentice Hall 10 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 11 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 12 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 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 The Internet uses 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. Internet Applications: Communication and Connection

 2002 Prentice Hall 15 An server acts like a local post office for a particular Internet host—a business, an organization, or an ISP. File servers are common within LANs, but they’re also used to share programs, media files, and other computer data across the Internet. Internet Applications: Communication and Connection

 2002 Prentice Hall 16 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. Internet Applications: Communication and Connection

 2002 Prentice Hall 17 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. Internet Applications: Communication and Connection

 2002 Prentice Hall 18 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 Web

 2002 Prentice Hall 19 Inside 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 20 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

 2002 Prentice Hall 21 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

 2002 Prentice Hall 22 Web Addresses A typical URL looks like this:

 2002 Prentice Hall 23 Web Addresses Protocol for Web pages Dissecting Web Page address: Path to the host Resource Page help/database.html

 2002 Prentice Hall 24 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 25 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 26 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 27 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 28 From Hypertext to Multimedia Plug-Ins are software extensions that add new features. Examples include… QuickTime Shockwave/Flash RealPlayer Acrobat

 2002 Prentice Hall 29 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 30 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

 2002 Prentice Hall 31 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