The Internet and the World Wide Web • HTTP Servers(Hypertext Transfer Protocol) • Web Browsers (Internet Explorer, Netscape Navigator, Firefox)) • Web Pages with • hyperlinks TELNET FTP E-MAIL THE INTERNET USENET WWW
World Wide Web Components • Packet Switching/Routing • Networks (LANS & WANS) • TCP/IP Communications Protocol • Client/Server Computing • Web Pages
Internet Backbone – U.S. Source: http://www.accd.edu/sac/lrc/john/wwwtest2.htm
Routing Demo www.visualroute.com http://pages.ebay.com.cn/welcome/index.html
Application Layer SSL (Secure Sockets Layer) Transport Layer Network Layer TCP/IP Protocol • The TCP/IP protocol controls assembly & disassembly of a file into packets for transmission over the Internet HTTP, FTP, Telnet, DNS,SMTP TCP Network Data Packets IP 101001 1101001 101101
Packet-Switching Networks • Digital data are sliced into packets, and sent over network on different paths then reassembled at their destination. • Routers: special purpose computers that interconnect computer networks and route packets to their ultimate destination • Routers use routing algorithms to ensure packets take the best available path
IP Addressing Internet Protocol Version 4 (IPv4) • A 32-bit number to identify computers connected to the Internet Sample IP Address: 220.127.116.11
TCP/IP Application Suite HTTP FTP Web Pages File Transfer
TCP/IP Application Suite SMTP TELENET E-Mail Terminal Emulation
ICANN ICANN is responsible for the global coordination of the Internet's system of unique identifiers such as domain names and addresses
Domain Names • A Domain Name is a set of words assigned to a specific IP address. • Protocol Name + Domain Name or IP Address = Uniform Resource Locator (URL). ftp://www.pcwebopedia.com/stuff.exe http://www.pcwebopedia.com/index.htmlhttp://18.104.22.168 http://www.secondleveldomain.topleveldomain
Domain Names • Unrestricted(e.g.,.com. .net, .org) • Restricted(.edu, .gov, .mil) • Country(e.g., .us, .cc, .tv) • New Domain Names (e.g.,.aero, .biz, .coop, .info, .jobs, .mobi, .museum, .name, .pro, .travel) • Vanity Domain names (e.g., .tv)
County Code Domain Nameshttp://www.iana.org/root-whois/index.html
Domain Naming Issues • 2-63 Characters (A-Z, 0-9, “-”) • No “-” at Beginning or End • Brand Names & Cybersquatting • Dot-Com is Most Respected • Not Case Sensitive • Typically Represents a Business, or Product or Service Name, + Other Uses • About Registration & Name Ownership http://www.oreillynet.com/onlamp/blog/2005/06/the_worlds_longest_domain_name.html
Client-Server Computing • Web Client Computer • Runs software called Web client software or Web Browser software • Web Server Computer • Runs software called Web server software
Domain Name System (DNS) The Domain Name System (DNS) associates Domain Names with IP Addresses. Functionally, it’s a Web Page Phone Book. DNS IP Addresses URL is Resolved to IP Address www.abc.com 22.214.171.124 abc.com Home Page Hosting Server IP Address 126.96.36.199 Web Pages
Whois Search Whois is used to determine who the URL is registered to.
Electronic Mail Protocols • SMTP (Simple Mail Transfer Protocol) - specifies the format of a mail message • POP (Post Office Protocol) – used to retrieve e-mail from a server. • MIME (Multipurpose Internet Mail Extensions) – provides Support for graphics, audio & video content.
W3C The World Wide Web Consortium (W3C) is an international consortium that develops protocols and guidelines for the Web.
Standard Generalized Markup Language (SGML) • Offers a system of marking up documents that is independent of any software application. • Used to Create Other Markup Languages.
Hypertext Markup Language (HTML) • Prevalent markup language used to create Web pages • HTML tags are interpreted by a Web browser and are used by it to format the display of the text • HTML links can be structured as: • Linear hyperlink structures • Hierarchical hyperlink structures
Extensible Markup Language (XML) • It includes data management capabilities that HTML cannot provide • XML, HTML & XHTML: • XML does not have pre-defined tags. • XML tags do not specify how text appears on a Web page. • XHTML is a markup language written in XML that has a stricter syntax than HTML.
Intranets and Extranets • Intranet • Interconnected network that does not extend beyond the organization that created it • Extranet • Intranet extended to include entities outside the boundaries of an organization • Connects companies with suppliers, business partners, or other authorized users
Networks • Public network • A network available to the public. • Private network • A private, leased-line connection between two companies that physically connects their intranets.
Virtual Private Network (VPN) • VPN • An extranet that uses public networks and their protocols • VPN software must be installed on the computers at both ends of the transmission
Internet Connection Options • Bandwidth • Amount of data that can travel through a communication line per unit of time • Net bandwidth • Actual speed that information travels
Voice-Grade Telephone Connections • POTS, or plain old telephone service • Uses existing telephone lines and an analog modem • Provides bandwidth between 28 and 56 Kbps • Digital Subscriber Line (DSL) • Connection methods that do not use a modem • Integrated Services Digital Network (ISDN) • Bandwidths between 128 Kbps and 256 Kbps
Broadband Deployment Broadband defined as greater than 200 Kbps • Asymmetric digital subscriber line (ADSL) • Cable Modem • Fixed Point Wireless Broadband • DSL • Satellite
Leased-Line Connections • DS0 (digital signal zero) • Telephone line designed to carry one digital signal • T1 line (also called a DS1) • Carries 24 DS0 lines and operates at 1.544 Mbps • Fractional T1 • Provides service speeds of 128 Kbps and upward in 128-Kbps increments • T3service (also called DS3) • Offers 44.736 Mbps
Wireless ConnectionsBluetooth • Designed for personal use (Personal Area Networks) over short distances (Up to 100 meters) • Speeds of up to 722 Kbps • Devices can discover each other and exchange information automatically
Wireless Ethernet (Wi-Fi – Wireless LANs) Protocols based on IEEE 802.11 Standard
Mobile Networks • Cellular - Third-generation (3G) Technology Cell Phones • Mobile commerce (m-commerce)
Internet 2 • Internet2 or UCAID (University Corporation for Advanced Internet Development) – A nonprofit consortium of universities and corporations which is developing an advanced, high-speed network for education and research. • Not to be confused with Web 2.0 - which is the unofficial “social networking & collaborative” Web.
Social Networking (Web 2.0) • Wikipedia, Blogs, RSS Feeds, Facebook, YouTube • Nearly 2 in 5 U.S. Internet Users Watched a YouTube Video in September 2007. • Nearly 70 million people viewed more than 2.5 billion videos on YouTube.com. • More than 38 million people viewed approximately 360 million videos on MySpace.com Source: comScore Video Metrix