Lesson 2 Chapter 3 The Internet Intranets and

Lesson 2 Chapter 3 The Internet, Intranets, and Extranets

Learning Objectives Define how the Internet works Describe the services associated with the Internet Describe the World Wide Web Define the terms intranet and extranet and discuss how organizations use them Identify who is using the Web to conduct business Chapter 3 Slide 2

The Internet (Figure 7. 1) The Internet transmits data from one computer (called a host) Chapter 3 to another. Internet Networks Linked networks that work much the same way -- they pass data around in packets, each of which carries the addresses of its sender and receiver. Slide 4

Use and Functioning of the Internet Interconnected networks Global though US is the largest user Internet Protocol (IP) Research for a faster Internet l Internet 2 (I 2) l Next Generation Internet (NGI) l Corporate efforts Chapter 3 Slide 5

How the Internet Works Hosts with Uniform Resource Locator (URL) Routers forward packets to other networks Internet Protocol Stack (TCP/IP) l l Internet Protocol (IP) Transport Control Protocol (TCP) Backbones l Chapter 3 One of the Internet’s high-speed, long distance communications links. Slide 6

How the Internet Works Uniform Resource Locator (URL) http: //www. whitehouse. gov World Wide Web Hypertext transfer protocol Chapter 3 Domain category Host Network Name Slide 7

The Internet is Based on the Client-Server Model In client/server computing, processes are divided between the client and the server. This relationship is based on a series of requests and responses. Chapter 3 n Client: Requests services or information from another computer (the server computer). n Server: Responds to the client's request by sending the results of the request back to the client computer. Slide 8

Client - Server Computing Chapter 3 Slide 9

The Client-Server Model This diagram illustrates the relationship between client and server computers. The client requests information; the server processes the request and sends a response back to the client. CLIENT SERVER REQUEST Client Program RESPONSE Server Program Chapter 3 Send Request Process Request Read Results Send Back Results Slide 10

Examples of Client Server Transactions FTP (file transfer protocol) - An FTP client program contacts an FTP server and requests the transfer of a file; the FTP server responds by transferring the file to the client. WWW (World Wide Web) - In this case the client program is a browser. A browser requests the contents of a web page and displays the results on the user's computer. E-MAIL - A mail client program enables the user to interact with a server in order to access, read and send electronic mail messages. Chapter 3 Slide 11

Packets: The Internet “Letter” To: Destination: From: Instruction Fields: Data Chapter 3 Slide 12

What is a Packet? A packet is a single unit, or "package", of data that is sent across a network. Data is broken into packets before it is sent across the Internet. Types of data that are sent across the Internet using packets include: Chapter 3 n E-mail messages n Files, via File Transfer Protocol (FTP) n Web pages, via the World Wide Web (WWW) Slide 13

Parts of the Packet The HEADER of a packet contains both the originating and destination IP (Internet Protocol) address. The header also contains coding to handle transmission errors and keep packets flowing. Routers use the data in the header to get the packet to the correct address and to reassemble it at the destination. Chapter 3 To: Destination: From: Instruction Fields: Data The DATA portion of the packet contains the e-mail text, the web page information, or the contents of the file. Slide 14

Transmission Control Protocol/Internet Protocol (TCP/IP ) TCP/IP is a collection of protocols, or rules, that govern the way data travels from one machine to another across networks. The Internet is based on TCP/IP. Chapter 3 Slide 17

Internet Protocol n. Determines n. Breaks how much data can fit into a single packet the data into packets. Places header information into the packet, enabling the packet to be forwarded from router to router until it reaches the final destination. . n Chapter 3 Slide 18

Packet Switching Example Hi Bob! Chapter 3 Slide 20

Packet Switching Example Hi Bob! Hi Bob! Chapter 3 Hi Bob! Slide 21

Packet Switching Example Hi Bob! Router 192. 233. 123. 154 Hi Bob! Chapter 3 Slide 22

Packet Switching Example Hi Bob! Chapter 3 Slide 23

Packet Switching Example Hi Bob! Hi Bob! Chapter 3 Hi Bob! Slide 24

U. S. Top-Level Domain Affiliations Affiliation ID arts com edu firm gov info mil nom net org rec store web net 3 Chapter Affiliation cultural and entertainment activities business organizations educational sites businesses and firms government sites information service providers military sites individuals networking organizations recreational activities businesses offering goods for purchase entities related to World Wide Web activities networking organizations Slide 25

Accessing the Internet Fig 7. 2 Chapter 3 Slide 26

Internet Service Providers (ISPs) Provide Internet access to account holders Monthly fee varies Some are free Chapter 3 Slide 27

Internet Service Providers Internet Service Provider Web Address AT&T World. Net Service Digex, Inc. GTE Internetworking IBM Internet Connection MCI Internet Net. Com On-Line Communication Services PSINet, Inc. Sprint Internet Services Uunet Technologies, Inc. www. att. com www. digex. net www. gte. net www. ibm. net www. mci 2000. com www. netcom. com www. psinet. com www. sprint. net www. us. uu. net Chapter 3 Slide 28

Internet Services E-mail (Electronic mail) Can include images, attachments, or HTML l Routed by gateways and routers l Telnet: remote login FTP: file transfer Chapter 3 Slide 29

Internet Services Chat rooms: allow interactive conversations Instant Messaging: online, real-time communication over the Internet Videoconferencing Internet phone Chapter 3 Slide 30

Internet Services Content streaming: transfers multimedia files continuously so users can view them in real-time Music, radio & video 3 -D Internet sites Chapter 3 Slide 32

The World Wide Web

The WWW is Just a Part of the Internet The World Wide Web, also referred to as the WWW and "the Web, " is the universe of information available via hypertext transfer protocol (HTTP). The World Wide Web and HTTP: n n n Chapter 3 allow you to create "links" from one piece of information to another; can incorporate references to sounds, graphics, and movies, etc. ; "understand" other Internet protocols, such as ftp, gopher, and telnet. Slide 34

WWW Pages use Hyperlinks The Web presents information as a series of "documents, " often referred to as web pages, that are prepared using the Hypertext Markup Language (HTML). Using HTML, the document's author can specially code sections of the document to "point" to other information resources. These specially coded sections are referred to as hypertext links. Users viewing the webpage can select the hypertext link and retrieve or connect to the information resource that the link points to. Webpage Software Repository (ftp) Chapter 3 link Library Catalog (telnet) gopher site w/ images & sounds Slide 35

The World Wide Web A collection of tens of thousands of independently-owned computers that work together as one in an Internet service. Uses a menu-based approach and hyperlink technology in a client/server topology. Chapter 3 Home Page The cover page for a Web site that has graphics, titles, and black and blue text. Hypermedia Tools that connect the data on Web pages, allowing users to access topics in whatever order they wish. Slide 36

Uniform Resource Locators (URL) Identify Sources of Data on The Internet A URL identifies a particular Internet resource. e. g. a Web page, a gopher server, a library catalog, an image, or a text file. URLs represent a standardized addressing scheme for Internet resources. The basic structure of a URL is hierarchical moving from left to right: protocol: //server-name. domain-name. top-level domain: port/directory/filename Examples: lhttp: //www. healthyway. com: 8080/exercise/mtbike. html lgopher: //gopher. state. edu/ lftp: //ftp. company. com/ Chapter 3 Slide 37

Several Interesting Web Sites Chapter 3 Library of Congress http: //lcweb. loc. gov Point. Cast http: //www. pointcast. com In-Box Direct http: //www. netscape. com Online Career Center http: //occ. com New York Times http: //www. nytimes. com Project Gutenberg http: //www. gutenberg. org Sportsline USA Slide 38 http: //www. sportsline. com

Web Terminology Web Server: Computer that stores web pages. Web Browser l Software that creates a unique hypermedia-based menu on your computer screen and provides a graphical interface to the Web Page l A screen of information sent to a requesting user and presented through a browser. Applet l A small program embedded in Web pages Search engines l Chapter 3 Programs to find web pages of interest. Slide 39

Internet Services Shopping on the Web Bots: web search tools Web Auctions Office on the web Chapter 3 Slide 40

Webcasting aka Push Technology Consolidates information according to a user’s profile & displays in the browser Chapter 3 Slide 41

Intranets and Extranets Intranet l An internal corporate network built using Internet and World Wide Web standards and products that allows employees of an organization to gain access to corporate information. Extranet l Chapter 3 A network based on Web technologies that links selected resources of the intranet of a company with its customers, suppliers, or other business partners. Slide 42 22

Questions? Chapter 3 Slide 43