AGENDA: StarHub case debrief Infrastructure for e-commerce In-class exercise: Blog analysis HTML lab Session 2: Technology Infrastructure: The Internet and the Web

Objectives In this chapter, you will learn about: The origin, growth, and current structure of the Internet How packet-switched networks are combined to form the Internet How Internet protocols and Internet addressing work The history and use of markup languages on the Web, including SGML, HTML, and XML

In this chapter, you will learn about:

The origin, growth, and current structure of the Internet

How packet-switched networks are combined to form the Internet

How Internet protocols and Internet addressing work

The history and use of markup languages on the Web, including SGML, HTML, and XML

Objectives How HTML tags and links work on the World Wide Web The differences among internets, intranets, and extranets Options for connecting to the Internet, including cost and bandwidth factors About Internet2 and the Semantic Web

How HTML tags and links work on the World Wide Web

The differences among internets, intranets, and extranets

Options for connecting to the Internet, including cost and bandwidth factors

About Internet2 and the Semantic Web

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

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

Origins of the Internet Early 1960s U.S. Department of Defense funded research to explore creating a worldwide network In1969, Defense Department researchers Connected four computers into network called ARPANET Throughout 1970s and 1980s Academic researchers connected to ARPANET and contributed to its technological developments

Early 1960s

U.S. Department of Defense funded research to explore creating a worldwide network

In1969, Defense Department researchers

Connected four computers into network called ARPANET

Throughout 1970s and 1980s

Academic researchers connected to ARPANET and contributed to its technological developments

New Uses for the Internet 1972 E-mail born Mailing list (listserve) E-mail address that forwards all messages received to any user who subscribed to the list Usenet Started by group of students and programmers at Duke University and University of North Carolina External returns to use

1972

E-mail born

Mailing list (listserve)

E-mail address that forwards all messages received to any user who subscribed to the list

Usenet

Started by group of students and programmers at Duke University and University of North Carolina

External returns to use

Growth of the Internet In 1991, NSF Eased restrictions on commercial Internet activity Began implementing plans to privatize the Internet Network access points (NAPs) Basis of new structure Internet Network access providers Sell Internet access rights directly to larger customers and indirectly to smaller firms and individuals through ISPs

In 1991, NSF

Eased restrictions on commercial Internet activity

Began implementing plans to privatize the Internet

Network access points (NAPs)

Basis of new structure Internet

Network access providers

Sell Internet access rights directly to larger customers and indirectly to smaller firms and individuals through ISPs

Growth of the Internet

World Wide Web The Web Software that runs on computers connected to the Internet Vannevar Bush Speculated that engineers would eventually build a memory extension device (the Memex) In the 1960s Ted Nelson described a similar system called hypertext

The Web

Software that runs on computers connected to the Internet

Vannevar Bush

Speculated that engineers would eventually build a memory extension device (the Memex)

In the 1960s

Ted Nelson described a similar system called hypertext

Emergence of the World Wide Web (Continued) Tim Berners-Lee Developed code for hypertext server program Hypertext server Stores files written in hypertext markup language Lets other computers connect to it and read files Hypertext Markup Language (HTML) Includes set of codes (or tags) attached to text Browser displays text and images on client (1994)

Tim Berners-Lee

Developed code for hypertext server program

Hypertext server

Stores files written in hypertext markup language

Lets other computers connect to it and read files

Hypertext Markup Language (HTML)

Includes set of codes (or tags) attached to text

Browser displays text and images on client (1994)

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

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

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

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

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

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

Router-based Architecture of the Internet

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

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

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

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

The Heart of the Internet? “It’s the TCP/IP Protocol Stack” Applications Web Email Video/Audio TCP/IP Access Technologies Ethernet (LAN) Wireless (LMDS, WiFi, Cellular) Cable DSL Satellite TCP/IP Applications Access Technologies “ Choke Point” Middleware Services Network Technology Substrate Supply

Applications

Web

Email

Video/Audio

TCP/IP

Access Technologies

Ethernet (LAN)

Wireless (LMDS, WiFi, Cellular)

Cable

DSL

Satellite

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 IP V6 extends addressing, control functionality

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

IP V6 extends addressing, control functionality

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

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

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

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

Top-level Domain Names

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

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

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)

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)

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

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

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)

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)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Wireless Ethernet (Wi-Fi or 802.11b/g/n) 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 11-54 Mbps and range of about 300 feet (n >100 Mbps) Devices capable of roaming

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 11-54 Mbps and range of about 300 feet (n >100 Mbps)

Devices capable of roaming

Wireless Ethernet (Wi-Fi or 802.11a/b/g/n) 802.11a protocol Capable of transmitting data at speeds up to 54 Mbps, on different frequencies to 802.11b 802.11g protocol Has 54 Mbps speed of 802.11a Compatible with 802.11b devices 802.11n emerging standard Expected to offer speeds up to 320 Mbps

802.11a protocol

Capable of transmitting data at speeds up to 54 Mbps, on different frequencies to 802.11b

802.11g protocol

Has 54 Mbps speed of 802.11a

Compatible with 802.11b devices

802.11n emerging standard

Expected to offer speeds up to 320 Mbps

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 acting as routers

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 acting as routers

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

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

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

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

Internet2 and the Semantic Web (Continued) Semantic Web Project by Tim Berners-Lee If successful Would result in words on Web pages being tagged (using XML) with their meanings Resource description framework (RDF) Set of standards for XML syntax Ontology Set of standards that defines relationships among RDF standards and specific XML tags

Semantic Web

Project by Tim Berners-Lee

If successful

Would result in words on Web pages being tagged (using XML) with their meanings

Resource description framework (RDF)

Set of standards for XML syntax

Ontology

Set of standards that defines relationships among RDF standards and specific XML tags

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

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

Development of Markup Languages

Standard Generalized Markup Language Offers a system of marking up documents that is independent of any software application Nonproprietary and platform independent Offers user-defined tags Costly to set up and maintain

Offers a system of marking up documents that is independent of any software application

Nonproprietary and platform independent

Offers user-defined tags

Costly to set up and maintain

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

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

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

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

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

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

Processing a Request for an XML Page

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)

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)

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

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