1 / 35

CHAPTER 7

CHAPTER 7 THE INTERNET AND INTRANETS What is the Internet? The Largest computer network in the world (a network of networks) Exchanges information seamlessly by using the same open, non-proprietary standards and protocols, within interconnected networks

Ava
Télécharger la présentation

CHAPTER 7

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. CHAPTER 7 THE INTERNETAND INTRANETS

  2. What is the Internet? • The Largest computer network in the world (a network of networks) • Exchanges information seamlessly by using the same open, non-proprietary standards and protocols, within interconnected networks • Forms a massive electronic communications network • Provides a true democratic communications forum and has produced a democratization of information Marina G. Erechtchoukova

  3. The Evolution of the Internet Marina G. Erechtchoukova

  4. The Infrastructure of the Internet • Commercial communications carriers provide the physical network backbone of the Internet • Internet Service Providers: • Backbone providers • Access providers • Reciprocal agreement Marina G. Erechtchoukova

  5. The Operation of the Internet • Internet is packet-switched network • Client-Server architecture • Internet Protocol • Internet Model Marina G. Erechtchoukova

  6. Internet Model • Interface layerdefines physical medium and frame for flow and error control • Internet network layer defines the path to intended receiver in the network. Uses Internet Protocol (IP) • Internet transport layer provides point-to-point reliable transmission of data. Uses TCP and UDP. • Internet application layer supports network application Marina G. Erechtchoukova

  7. OSI Model vs. Internet Model Marina G. Erechtchoukova

  8. Internet Application Layer • File Transfer Protocol • Telnet • Simple Mail Transfer Protocol • Simple Network Management Protocol • HyperText Transfer Protocol • Domain Name System Marina G. Erechtchoukova

  9. Addresses on the Internet • IP address uniquely identifies each computer in the network • Example: 130.63.160.120 • The necessity to keep a master table with IP addresses on each router • Hard to remember for people • Domain name system (DNS) - derives the names of the computers Marina G. Erechtchoukova

  10. Domain name system (DNS) • Domain – a group of networks • Domains are organized hierarchically • DNS is based on hierarchical database: • Variable-depth hierarchy • Distributed database • Examples:www.atkinson.yorku.ca www.yorku.ca Marina G. Erechtchoukova

  11. Accessing the Internet • Connect via LAN Server • Communications stack • Connect via Serial Line Internet Protocol/Point-to-point Protocol (SLIP/PPP) • Connect via an Online Service Marina G. Erechtchoukova

  12. Internet Services • Communications services • Information retrieval services • World Wide Web • Web services Marina G. Erechtchoukova

  13. Communications Services Provided by the Internet • E-mail • Mail Gateway – a computer dedicated to forwarding e-mail • USENET Newsgroups: • Bulletin board • Discussion threads (moderate vs. unmoderate) • LISTSERV • Chatting Marina G. Erechtchoukova

  14. Communications Services Provided by the Internet (continued…) • Telnet • Internet telephony: • Voice-over IP • Sharing digital lines • Disadvantages: • Low quality of sounds • Delays in transmission process Marina G. Erechtchoukova

  15. Communications Services Provided by the Internet (continued…) • Internet Fax • Content streaming: • Audio • Video • Real-time audio and video Marina G. Erechtchoukova

  16. Information Retrieval Services • FTP service • File Transfer Protocol can be used to copy an arbitrary file from one computer to another • Client–Server architecture • A control connection is established to a remote computerand remains in place until the user closes it. • Data connection • File name translation • Archie searches the file on FTP sites Marina G. Erechtchoukova

  17. Information Retrieval Services (continued…) • Gopher – distributed document delivery system: • Based on TCP • Flow control and sequencing • Acknowledgment and Retransmission • Checksums • Veronica searches text in Gopher menus Marina G. Erechtchoukova

  18. The World Wide Web • The Internet functions as the transport mechanism • The World Wide Web - a system with universally accepted standards for storing, retrieving, formatting, and displaying information • Web Servers – support WWW application, are scattered all over the world Marina G. Erechtchoukova

  19. Web site • Web Site • Home Page - first, introductory page in a web site • Webmaster - the person in charge of a Web site • Uniform Resource Locator (URL) Marina G. Erechtchoukova

  20. Hypertext Transfer Protocol (HTTP) communications standard used to transfer pages across the WWW • Web client establishes connection with server • Web server receives a request • Web server sends a message • The connection is closed, if Web client does not use “keep alive” option Marina G. Erechtchoukova

  21. Browser • software application that is used to access and navigate the Web • Netscape Communicator • a multipurpose suite that handles news, e-mail, audio- and video conferencing, and more • Microsoft Internet Explorer • Internet Explorer’s tight integration with Windows offers users the advantage of “one-stop computing” • Offline Browser • enables a user to retrieve pages automatically from Web sites at predetermined times Marina G. Erechtchoukova

  22. Search Engines • Programs that return a list of Web sites or pages that match some user-selected criteria • Ways to select pages for inclusion in the database: • Web Crawlers • Registration • Methods for information search: • Depth first • Breadth first • Metasearch engines Marina G. Erechtchoukova

  23. Push vs. Pull Technology • Pull Technology – users select and retrieve information from the Web • Push Technology automatically supplies information to users by means of a process running on either the user’s desktop or a network server • provides timely, prioritized distribution of information over a corporate network in the workplace • enhances traditional Web advertising in the consumer market Marina G. Erechtchoukova

  24. Web Services • Information Filters • Platform for Internet Content Selection • Intelligent agents • Clipping Services • track news topics and retrieve articles from database of publications • Personalized Web Services • offer the ability to generate Web content that is personalized for individual Web site visitors • Collaborative Filtering Marina G. Erechtchoukova

  25. Web Authoring • Standard HTML is the common denominator • Enhancements to HTML • Dynamic HTML (DHTML) • Extensible markup language (XML) • Voice markup language (VoxML) • Virtual reality modeling language (VRML) • HTML editors, generators, publishers Marina G. Erechtchoukova

  26. Internet Challenges • New Technologies • Vendors are adopting new technologies more rapidly than users can implement them • Internet Regulation • WWW Consortium, Internet Engineering Task Force – technical standards • Content regulation • Internet Expansion Marina G. Erechtchoukova

  27. Internet Privacy • Web sites collect information about visitors: • Registration • Clickstream data • Cookie is a mechanism that supports restoring client states • small data file placed on users’ hard drives when they first visit a site • Encrypting Marina G. Erechtchoukova

  28. Intranets • A private network that uses Internet software and TCP/IP protocols • Process business data and information efficiently: • Data and information search • Urgent information delivery • Information distribution Marina G. Erechtchoukova

  29. Intranet operation • Intranet documents – HTML pages • HTTP – used to transmit documents • Browsers – allow to view Intranet documents • Supports applications to solve business problems • Intranet vs. traditionalnetworks: • HTTP and HTML platform independent • A single input point – a browser Marina G. Erechtchoukova

  30. Intranet software • Teamware • used for team building, sharing ideas and documents, brainstorming, scheduling, and archiving decision to facilitate productivity • Add-on to groupware Marina G. Erechtchoukova

  31. Security • Public Key security • Encryption • Digital certificates • Firewalls • Set of rules placed on the router • One or more computers • Assured pipelines Marina G. Erechtchoukova

  32. Extranet • A network that links business partners to one another over the Internet by providing access to certain areas of each other’s corporate intranets • Components • Intranets of business partners • Internet as communications links Marina G. Erechtchoukova

  33. Extranet infrastructure • Telecommunications systems (VPNs) • TCP/IP Protocols • Internet Services • Intranets infrastructure Extranet Company A Company B Intranet corporate data, e-mail, orders, customer data, inventory, documents Internet Intranet Internet Internet Internet Other users customers, suppliers, contractors, distributors, government Corporate employees travelling or at home Marina G. Erechtchoukova

  34. Types of Extranet • A company and its dealers, customers, or suppliers • centered around one company • An industry’s extranet teamed up and created by the major players in an industry • Joint ventures and other business partnerships • used for communications and collaboration among several companies partnering in a joint venture Marina G. Erechtchoukova

  35. Benefits of Extranets • Reduce the number of help-desk and data-entry employees • Improve quality of data and information exchange • Accelerate processes and information flows • Reduce paperwork • Provide better communications Marina G. Erechtchoukova

More Related