internet technologies
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Internet technologies. The Internet and the World Wide Web. Computer network Any technology that allows people to connect computers to each other The Internet A large system of interconnected computer networks spanning the globe World Wide Web A subset of computers on the Internet . - PowerPoint PPT PresentationTRANSCRIPT
Internet technologies
E-Commerce: The Second Wave, Fifth Annual Edition 2
The Internet and the World Wide Web
• Computer network– Any technology that allows people to connect
computers to each other
• The Internet – A large system of interconnected computer
networks spanning the globe
• World Wide Web– A subset of computers on the Internet
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Growth of the Internet
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Packet-Switched Networks
• Local area network (LAN)– Network of computers located close together
• Wide area networks (WANs)– Networks of computers connected over
greater distances
• Circuit– Combination of telephone lines and closed
switches that connect them to each other
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LAN (Local Area Network)
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MAN (Metropolitan Area Network)
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WAN (Wide Area Network)
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Packet-Switched Networks (Continued)
• Circuit switching– Centrally controlled, single-connection model
• Packets– Files and e-mail messages on a packet-
switched network that are broken down into small pieces
– Travel from computer to computer along the interconnected networks until they reach their destinations
E-Commerce: The Second Wave, Fifth Annual Edition 9
E-Commerce: The Second Wave, Fifth Annual Edition 10
Routing Packets
• Routing computers– Computers that decide how best to forward
packets• Routing algorithms
– Rules contained in programs on router computers that determine the best path on which to send packet
– Programs apply their routing algorithms to information they have stored in routing tables
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Router-based Architecture of the Internet
E-Commerce: The Second Wave, Fifth Annual Edition 12
Internet Protocols• Protocol
– Collection of rules for formatting, ordering, and error-checking data sent across a network
• Rules contributing to success of Internet– Independent networks should not require any
internal changes to be connected to the network– Packets that do not arrive at their destinations
must be retransmitted from their source network– Router computers act as receive-and-forward
devices– No global control exists over the network
E-Commerce: The Second Wave, Fifth Annual Edition 13
TCP/IP
• TCP– Controls disassembly of a message or a file
into packets before transmission over Internet
– Controls reassembly of packets into their original formats when they reach their destinations
• IP – Specifies addressing details for each packet
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IP Addressing• Internet Protocol version 4 (IPv4)
– Uses a 32-bit number to identify computers connected to the Internet
• Base 2 (binary) number system– Used by computers to perform internal
calculations• Subnetting
– Use of reserved private IP addresses within LANs and WANs to provide additional address space
E-Commerce: The Second Wave, Fifth Annual Edition 15
IP Addressing (Continued)
• Private IP addresses– Series of IP numbers not permitted on packets
that travel on the Internet• Network Address Translation (NAT) device
– Used in subnetting to convert private IP addresses into normal IP addresses
• Internet Protocol version 6 (IPv6) – Protocol that will replace IPv4– Uses a 128-bit number for addresses
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Domain Names
• Sets of words assigned to specific IP addresses
• Top-level domain (or TLD)– Rightmost part of a domain name
• Internet Corporation for Assigned Names and Numbers (ICANN)– Responsible for managing domain names and
coordinating them with IP address registrars
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Top-level Domain Names
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Domain Names
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Web Page Request and Delivery Protocols
• Web client computers– Run software called Web client software or
Web browser software • Web server computer
– Runs software called Web server software• Client/server architecture
– Combination of client computers running Web client software and server computers running Web server software
E-Commerce: The Second Wave, Fifth Annual Edition 20
Web Page Request and Delivery Protocols (Continued)
• Hypertext Transfer Protocol (HTTP)– Set of rules for delivering Web page files over
the Internet • Uniform Resource Locator (URL)
– Combination of the protocol name and domain name
– Allows user to locate a resource (the Web page) on another computer (the Web server)
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E-Commerce: The Second Wave, Fifth Annual Edition 22
Electronic Mail Protocols
• Electronic mail (e-mail)– Must also be formatted according to common
set of rules• E-mail server
– Computer devoted to handling e-mail• E-mail client software
– Used to read and send e-mail– Example: Microsoft Outlook, Netscape
Messenger
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Electronic Mail Protocols (Continued)• Simple Mail Transfer Protocol (SMTP)
– Specifies format of a mail message• Post Office Protocol (POP)
– POP message can tell the e-mail server to• Send mail to user’s computer and delete it from
e-mail server• Send mail to user’s computer and not delete it• Simply ask whether new mail has arrived
– Provides support for Multipurpose Internet Mail Extensions (MIME)
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E-Commerce: The Second Wave, Fifth Annual Edition 25
Markup Languages and the Web
• Text markup language – Specifies set of tags that are inserted into text
• Standard Generalized Markup Language (SGML)– Older and complex text markup language– A meta language
• World Wide Web Consortium (W3C)– Not-for-profit group that maintains standards
for the Web
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Development of Markup Languages
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Hypertext Markup Language (HTML)
• Prevalent markup language used to create documents on the Web today
• HTML tags– Interpreted by Web browser and used by it to
format the display of the text
• HTML Links– Linear hyperlink structure– Hierarchical hyperlink structure
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Hypertext Markup Language (HTML) (Continued)
• Scripting languages and style sheets– Most common scripting languages
• JavaScript, JScript, Perl, and VBScript– Cascading Style Sheets (CSS)
• Sets of instructions that give Web developers more control over the format of displayed pages
• Style sheet– Usually stored in a separate file– Referenced using the HTML style tag
E-Commerce: The Second Wave, Fifth Annual Edition 29
Extensible Markup Language (XML)
• Uses paired start and stop tags
• Includes data management capabilities that HTML cannot provide
• Differences between XML and HTML– XML is not a markup language with defined
tags
– XML tags do not specify how text appears on a Web page
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Processing a Request for an XML Page
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Intranets and Extranets
• Intranet– Interconnected network that does not extend
beyond organization that created it
• Extranet– Intranet extended to include entities outside
boundaries of organization
– Connects companies with suppliers, business partners, or other authorized users
E-Commerce: The Second Wave, Fifth Annual Edition 32
Public and Private Networks• Public network
– Any computer network or telecommunications network available to the public
• Private network– A private, leased-line connection between two
companies that physically connects their intranets
• Leased line – A permanent telephone connection between
two points
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Virtual Private Network (VPN)• Extranet that uses public networks and their
protocols • IP tunneling
– Effectively creates a private passageway through the public Internet
• Encapsulation– Process used by VPN software
• VPN software– Must be installed on the computers at both
ends of the transmission
E-Commerce: The Second Wave, Fifth Annual Edition 34
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
• Symmetric connections – Provide same bandwidth in both directions
• Asymmetric connections – Provide different bandwidths for each direction
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Voice-Grade Telephone Connections• POTS, or plain old telephone service
– Uses existing telephone lines and analog modem
– Provide bandwidth between 28 and 56 Kbps• Digital Subscriber Line (DSL)
– Connection methods do not use modem• Integrated Services Digital Network (ISDN)
– Offers bandwidths between 128 Kbps and 256 Kbps
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Broadband Connections• Operate at speeds of greater than 200 Kbps• Asymmetric digital subscriber (ADSL)
– Transmission bandwidth is from 100 to 640 Kbps upstream and from 1.5 to 9 Mbps downstream
• Cable modems– Provide transmission speeds between 300 Kbps
and 1 Mbps• DSL
– Private line with no competing traffic
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Leased-Line Connections• DS0 (digital signal zero)
– Telephone line designed to carry 1 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
• T3 service (also called DS3)– Offers 44.736 Mbps
E-Commerce: The Second Wave, Fifth Annual Edition 38
Wireless Connections• Bluetooth
– Designed for personal use over short distances
– Low-bandwidth technology, with speeds of up to 722 Kbps
– Networks are called personal area networks (PANs) or piconets
– Consumes very little power– Devices can discover each other and
exchange information automatically
E-Commerce: The Second Wave, Fifth Annual Edition 39
Wireless Ethernet (Wi-Fi or 802.11b)
• Most common wireless connection technology for use on LANs
• Wireless access point (WAP) – Device that transmits network packets
between Wi-Fi-equipped computers and other devices
• Has potential bandwidth of 11 Mbps and range of about 300 feet
• Devices are capable of roaming
E-Commerce: The Second Wave, Fifth Annual Edition 40
Wireless Ethernet (Wi-Fi or 802.11b) (Continued)
• 802.11a protocol – Capable of transmitting data at speeds up to
54 Mbps• 802.11g protocol
– Has 54 Mbps speed of 802.11a – Compatible with 802.11b devices
• 802.11n– Expected to offer speeds up to 320 Mbps
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Fixed-Point Wireless
• One version uses system of repeaters to forward radio signal from ISP to customers
• Repeaters – Transmitter-receiver devices (transceivers)
• Mesh Routing– Directly transmits Wi-Fi packets through
hundreds, or even thousands, of short-range transceivers
E-Commerce: The Second Wave, Fifth Annual Edition 42
Cellular Telephone Networks
• Third-generation (3G) cell phones– Combine latest technologies available today
• Short message service (SMS)– Protocol used to send and receive short text
messages
• Mobile commerce (m-commerce)– Describes the kinds of resources people might
want to access using wireless devices
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Internet2 and the Semantic Web
• Internet2
– Experimental test bed for new networking technologies
– Has achieved bandwidths of 10 Gbps and more on parts of its network
– Used by universities to conduct large collaborative research projects
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Summary
• TCP/IP– Protocol suite used to create and transport
information packets across the Internet• POP, SMTP, and IMAP
– Protocols that help manage e-mail• Languages derived from SGML
– Hypertext Markup Language (HTML)– Extensible Markup Language (XML)
E-Commerce: The Second Wave, Fifth Annual Edition 45
Summary
• Intranets – Private internal networks
• Extranet– Used when companies want to collaborate
with suppliers, partners, or customers
• Internet2 – Experimental network built by a consortium of
research universities and businesses