BA 100 Chapter 2

Technology Infrastructure: The

Internet and the World Wide Web

CHAPTER 2

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Click to edit Master title styleLearning 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, e-mail, and Web protocols work • About Internet addressing and how Web domain

names are constructed

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Click to edit Master title styleLearning Objectives (cont’d.)

• About the history and use of markup languages on the Web

• How HTML tags and links work • About the cost and performance of Internet

connections technologies • About Internet2 and the Semantic Web

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Click to edit Master title styleIntroduction

• More Internet users are using smartphones or tablets – High mobile device usage is taxing existing

technologies and threatening to overloading networks • Current solution is for wireless providers to add

more cell phone towers – Expensive and locations can be hard to find

• With mobile data traffic expected to triple by 2018, the search for alternatives is underway – pCell technology creates a network of personal cells

based on each device

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Click to edit Master title styleThe Internet and the World Wide Web

• Computer network is any technology allowing people to connect computers to each other

• internet (small “i”) is a group of interconnected computer networks

• Internet (capital “I”) connects networks all over the world

• World Wide Web (Web) is a subset of Internet computers that are connected to each other – Includes easy-to-use interfaces

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Click to edit Master title styleOrigins of the Internet

• Early 1960s – Defense Department nuclear attack concerns – Powerful computers (large mainframes) – Leased telephone company lines established a single

connection between sender and receiver – Single connection risk solution

• Communicate using multiple channels (packets)

• 1969 Advanced Research Projects Agency (ARPA) – Packet network connected four computers

• ARPANET: earliest network (became the Internet) • Academic research use (1970s and 1980s)

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Click to edit Master title styleNew Uses for the Internet

• E-mail (1972) became widely used quickly • Military and education research users continued to

grow and mailing lists first appeared • 1979: Usenet (User’s News Network) created

– Continues today with newsgroups • Network applications improved and tested by an

increasing number of users from 1979 to 1989 – Security problems recognized

• 1980s: personal computer use explosion – Academic and research networks merged into the

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license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 7

Click to edit Master title styleCommercial Use of the Internet

• National Science Foundation (NSF) – Provided funding – Prohibited commercial network traffic so businesses

turned to commercial e-mail providers • Larger firms built networks (leased telephone lines) • 1989: NSF permitted two commercial e-mail

services (MCI Mail and CompuServe) – Commercial enterprises could send e-mail – Research, education communities sent e-mail directly

to MCI Mail and CompuServe

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Click to edit Master title styleGrowth of the Internet

• In 1991 the NSF further eased commercial Internet activity restrictions

• Privatization of the Internet completed in 1995 – Operations turned over to privately owned companies

• Internet based on four network access points (NAPs)

• Network access providers sell Internet access rights directly and through Internet service providers (ISPs)

• Consistent and dramatic growth in the number of Internet hosts (computers directly connected to the Internet) to more than 1 billion today

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FIGURE 2-1 Growth of the Internet

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Click to edit Master title styleThe Internet of Things

• Connection of devices not used by persons is rapidly increasing – Switches, optical scanners, and sensors can be

connected to the Internet and used to automatically manage environmental or security issues

– Some business transactions can be conducted without human intervention

• The Internet of things is the term used for these devices and automatic transaction processing – Estimated 10 billion devices now and expected to

reach 40 billion by 2020

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Click to edit Master title stylePacket-Switched Networks

• Local area network (LAN) is a network of computers located close together

• Wide area network (WAN) is a network of computers connected over greater distances

• Telephone call establishes a single connection path between caller and receiver then transmits data along that single path or circuit – Circuit switching is centrally controlled, single-

connection model – Not resistant to failure because a break in any circuit

causes interruption and data loss

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Click to edit Master title stylePacket-Switched Networks (cont’d.)

• Packet-switched network breaks files and e-mail messages into small pieces called packets – Labelled electronically with origin, sequences and

destination addresses – Travel along interconnected networks until reaching

destination • Can take different paths • May arrive out of order

– Destination computer • Collects packets • Reassembles original file or e-mail message

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Click to edit Master title styleRouting Packets

• Routing computers forward each packet – Routers, gateway computers, border or edge routers

• Routing algorithms are applied to information stored in routing tables or configuration tables

• Hubs, switches, and bridges move packets from one part of the network to another

• Routers connect networks to other networks and usually perform the required translation function

• Internet backbone are telecommunication lines and routers between Internet’s main collecting points

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FIGURE 2-2 Router-based architecture of the Internet

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Click to edit Master title stylePublic and Private Networks

• Public network is available to the public and does not provide much security as part of its basic structure

• Private network is a leased-line connection between two companies that physically connects their computers or networks together

• Leased line is a permanent telephone connection between two points – Advantage: security – Drawback: cost

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Click to edit Master title styleVirtual Private Network (VPN)

• Connection via public networks to send data in a way that protects it as well as a private network at a lower cost – Uses IP tunneling (encapsulation) system to create a

private passageway through public Internet • Encapsulation encrypts packet content and places it

inside another packet – IP wrapper: outer packet

• “Virtual” since connection seems permanent but is actually a temporary connection

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Click to edit Master title styleIntranets and Extranets

• Intranet – An Internet within the boundaries of the organization – Interconnected private networks

• Extranet – An Internet that extends beyond the organization and

incorporates networks of outside entities • Technologies (public networks, private networks, or

VPNs) – Independent of organizational boundaries

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Click to edit Master title styleInternet Protocols

• Protocol is a collection of rules across a network – Computers that communicate with each other must

use same protocol for data transmission • ARPANET: Network Control Protocol (NCP) • Proprietary architecture (closed architecture)

– Manufacturer creates own protocol • Open architecture (Internet core)

– Uses common protocol – Four key message-handling rules – Contributed to the Internet’s success

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Click to edit Master title styleTCP/IP

• Refers to the two main protocols used by the Internet today

• Transmission Control Protocol (TCP) – Controls message or file disassembly into packets

before Internet transmission – Controls packet reassembly into original formats at

destinations • Internet Protocol (IP)

– Specifies addressing details for each packet – Labels packet with origination and destination

addresses

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Click to edit Master title styleIP Addressing

• Internet Protocol version 4 (IPv4) used since 1981 • IP address is a 32-bit number identifying computers • Computers use base 2 (binary) number system

– Digit: 0 or a 1 (on or off condition) – Four billion different addresses

• Router breaks message into packets that contain source and destination IP address

• With dotted decimal notation IP addresses appear as four numbers separated by periods

• Three NFP organizations assign IP addresses

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Click to edit Master title styleIP Addressing (cont’d.)

• ARIN Whois server returns IP address list owned by an organization in North America

• New devices creating high demand for IP addresses – Subnetting is the use of reserved private IP LAN

(WAN) addresses to provide more space • Last IPv4 addresses allocated summer 2015 • Internet Protocol version 6 (IPv6) replaces IPv4 and

uses 128-bit number for addresses – Available addresses: 34 followed by 37 zeros – More complex hexadecimal (16) notation system

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Click to edit Master title styleElectronic Mail Protocols

• Electronic mail (e-mail) must be formatted according to common set of rules – Most organizations use a client/server structure

• E-mail server computer devoted to e-mail handling – Software stores and forwards e-mail messages

• E-mail client software reads and sends e-mail – Communicates with e-mail server software – Many e-mail services are offered by Web sites

• Standardization and rules are essential • Two common protocols are used for e-mail

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Click to edit Master title styleElectronic Mail Protocols (cont’d.)

• Simple Mail Transfer Protocol (SMTP) specifies mail message format, and describes mail administration and transmission

• Post Office Protocol (POP) messages send mail to user’s computer and either deletes or does not delete it or asks if new mail has arrived

• Multipurpose Internet Mail Extensions (MIME) is a set of rules for handling binary files

• Interactive Mail Access Protocol (IMAP) performs the same basic POP functions but has some additional features

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Click to edit Master title styleWeb Page Request and Delivery Protocols

• Web client computers run Web client software (Web browser software) – Examples include Google Chrome, Microsoft Internet

Explorer, Apple Safari and Mozilla Firefox • Sends Web page file requests to other computers (Web

servers)

• Web server computer runs Web server software – Receives requests from many different Web clients

and send back files • Client/server architecture

– Combination: client and Web server computers

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Click to edit Master title style Web Page Request and Delivery Protocols

(cont’d.)

• Hypertext Transfer Protocol (HTTP) – Internet Web page file delivery rules

• Web page request using Web browser – User types protocol name

• Followed by “//:” characters before the domain name – Uniform Resource Locator (URL)

• Combination: protocol name, domain name • Locates resources (Web page) on another computer

(Web server)

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Click to edit Master title styleEmergence of the World Wide Web

• Web – Software running on Internet-connected computers – Generates network traffic

• Web software: largest single traffic category • Outpaces: e-mail, file transfers, and other data

transmission traffic – Web resulted from new ways of thinking about

information storage and retrieval • Key technological Web elements

– Hypertext – Graphical user interfaces

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Click to edit Master title styleThe Development of Hypertext

• 1945: Vannevar Bush: The Atlantic Monthly article – Visionary ideas: future technology uses (Memex)

• 1960s: Ted Nelson described a page-linking system – Douglas Engelbart: experimental hypertext system

• 1987: Nelson published Literary Machines – Outlined project Xanadu an online global hypertext

publishing and commerce system • 1989: Tim Berners-Lee proposed development

project to provide data-sharing functionality – Developed hypertext server program code

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Click to edit Master title styleThe Development of Hypertext (cont’d.)

• Hypertext server stores files written in Hypertext Markup Language (HTML) which is used for the creation of Web pages – Called Web servers today

• HTML is a language that includes a set of codes (tags) attached to text – Describes relationships among text elements

• Hypertext link (hyperlink) – Points to another location – Same or another HTML document

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Click to edit Master title styleGraphical Interfaces for Hypertext

• Web browser – Software lets users read (browse) HTML documents

and move from one HTML document to another through text formatted with hypertext link tags in file

• Graphical user interface (GUI) – Presents program control functions, output to users,

and input from users – Pictures, icons, and other graphical elements

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Click to edit Master title styleThe World Wide Web

• World Wide Web: Berners-Lee’s name for system of hyperlinked HTML documents – Quick acceptance in scientific research community

• 1993: GUI program (Mosaic) that could read HTML – Used HTML hyperlinks for page-to-page navigation – First Web browser widely available for personal

computers and still in use today • Easy access to Internet information through system

of pages connected by hypertext links – Profit-making potential recognized by businesses

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Click to edit Master title styleThe World Wide Web (cont’d.)

• Netscape Communications founded in 1994 – Netscape Navigator Web browser (based on Mosaic) – Microsoft: Internet Explorer (most widely used) – Mozilla Firefox: Netscape Navigator descendant

• Number of Web sites has grown more rapid growth than the Internet itself – More than 800 million Web sites – Over a trillion individual Web pages – 2010 to 2011: number of Web sites doubled

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FIGURE 2-3 Growth of the World Wide Web

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Click to edit Master title styleThe Deep Web

• Web provides access to customized pages created in response to a user’s query – Pull content from databases – Example: search for “online business” book on

Amazon.com • Deep Web: Store of information available through

the Web – Potentially trillions of Web pages available using deep

Web – Difficult or impossible to search because available

data that is never requested remains hidden

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Click to edit Master title styleDomain Names

• Dotted decimal notation difficult to remember • Domain names are sets of words assigned to

specific IP addresses – Example: www.sandiego.edu

• Contains three parts separated by periods • Top-level domain (TLD): rightmost part • Generic top-level domains (gTLDs) • Sponsored top-level domains (sTLD)

• Internet Corporation for Assigned Names and Numbers (ICANN)

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FIGURE 2-4 Commonly used domain names

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Click to edit Master title styleMarkup Languages and the Web

• Text markup language specifies a set of tags inserted into text

• Markup tags (tags) provide formatting instructions Web client software understands

• Most commonly used markup language is HTML – Subset of Generalized Markup Language (SGML)

• World Wide Web Consortium (W3C) maintains Web standards

• Extensible Hypertext Markup Language (XHTML) – HTML version 4.0 reformulation as XML application

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Click to edit Master title styleHypertext Markup Language

• Hypertext elements are text elements related to each other

• HTML is the prevalent markup language to create Web documents – W3C HTML Working Group page maintains detailed

HTML versions and related topic information – HTML version 5.0 was released in 2014

• SGML is a metalanguage that can be used to define other languages – Extensible Markup Language (XML) was derived from

SGML and is used to tag shared information

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FIGURE 2-5 Development of markup languages

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Click to edit Master title styleHTML Tags

• Interpreted by the Web browser and used to format the display of text enclosed by the tags – Enclosed in angle brackets (<>) – Most have an opening tag and closing tag that format

the text between them – Closing tag is preceded by slash within the angle

brackets (</>) • User may customize tag interpretations so that

different browsers display tagged text differently • Tags are generally written in lowercase letters

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Click to edit Master title styleHTML Tags (cont’d.)

• One-sided tags require opening tag only – Common example is the tag that creates a line break

• Some two-sided tags have an optional closing tag – Common example is the paragraph tag

• Opening tag may contain one or more property modifiers that refines how the tag operates

• Other frequently used HTML tags allow Web designers to include graphics and format text as tables

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FIGURE 2-6 Text marked up with HTML tags

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FIGURE 2-7 Text marked up with HTML tags as it appears in a Web browser

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Click to edit Master title styleHTML Links

• Hyperlinks on interlinked pages form a “web” of those pages

• Linear hyperlink structure reads Web page in serial fashion – Works well when customer fills out form

• Hierarchical hyperlink structure uses an introductory page (home page, start page) that links to other pages – Site map often available for hierarchical sites

• HTML creates hyperlinks using HTML anchor tags

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FIGURE 2-8 Linear vs. nonlinear paths through documents

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FIGURE 2-9 Three common Web page organization structures

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Click to edit Master title styleCascading Style Sheets

• Style sheet is a set of instructions that gives Web developers control over displayed page formatting – Usually stored in a separate file and referenced using

HTML style tag – May be included in Web page’s HTML file

• Cascading style sheets (CSS) can be applied to each Web page, one on top of the other

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Click to edit Master title styleExtensible Markup Language (XML)

• HTML not a good tool for presenting large amounts of business data so designers turned to XML – Uses paired start and stop tags to define the structure

of a collection of data – Includes data-management capabilities HTML cannot

provide • Greatest strength (and weakness) of XML is that it

allows users to define their own tags – Many companies have agreed to common standards

for XML tags (data-type definitions (DTDs) or XML schemas) which are available for many industries

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FIGURE 2-10 Country list data marked up with HTML tags

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FIGURE 2-11 Country list data as it appears in a Web browser

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FIGURE 2-12 Country list data marked up with XML tags

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FIGURE 2-13 Country list data marked up with XML displayed in a Web browser

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Click to edit Master title style Extensible Markup Language (XML)

(cont’d.)

• Available DTDs or XML schemas include – LegalXML for the legal profession – MathML for mathematical and scientific information – Extensible Business Reporting Language (XBRL) for

accounting and financial information standards • Set of XML tag definitions called an XML vocabulary • XML files usually not intended to display in browser

– Extensible Stylesheet Language (XSL) contains formatting instructions

– XML parsers format XML file for device screen

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 53

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FIGURE 2-14 Processing requests for Web pages from an XML database

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Click to edit Master title styleInternet Connection Options

• Internet is a set of interconnected networks • Organizations connect computers using a network • Many families have their home computers

connected using a network • Mobile phones are connected to the wireless phone

service provider’s network • Internet access providers (IAPs) or ISPs

– Provide Internet access to individuals, businesses, other organizations

– Offer several connection options

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 55

Click to edit Master title styleConnectivity Overview

• Common connection options are voice-grade telephone lines, various types of broadband connections, leased lines, wireless

• Bandwidth is the amount of data traveling through communication medium per unit of time – Net bandwidth is actual data transmitted per second – Symmetric connections provide the same bandwidth

both directions – Asymmetric connections provide different bandwidths

for each direction

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 56

Click to edit Master title styleConnectivity Overview

• Two bandwidth types in an asymmetric connection are – Upstream bandwidth (upload bandwidth) is a measure

of amount of information that can travel from the user to the Internet in a given amount of time

– Downstream bandwidth (download, downlink bandwidth) is a measure of amount of information from the Internet to user in a given amount of time

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 57

Click to edit Master title styleVoice-Grade Telephone Connections

• Used in early days of Web • Plain old telephone service (POTS) uses existing

telephone lines, analog modem – Bandwidth between 28 and 56 Kbps

• Total most people use higher bandwidth connection options – Speeds greater than 200 Kbps are called broadband

services

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 58

Click to edit Master title styleBroadband Services

• Digital Subscriber Line (DSL) is a higher grade of telephone service that does not use a modem – Asymmetric digital subscriber line (ADSL) bandwidths

from 100 to 640 Kbps upstream and 1 to 15 Mbps downstream

– DSL: Private line with no competing traffic • Cable modems connect to the television cable

– Bandwidths from client to server: 500 Kbps to 15 Mbps with downstream as high as 10 Mbps

– Connection bandwidths vary with number of subscribers competing for shared resource

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 59

Click to edit Master title styleLeased-Line Connections

• Large firms can connect to an ISP using higher bandwidths leased from telecommunications carriers – Classified by equivalent number of telephone lines

included which are more expensive than other options • DS0 (digital signal zero) carries one digital signal (56

Kbps); T1 line (DS1) carries 24 DS0 lines (1.544 Mbps); T3 (DS3): 44.736 Mbps

• Technologies used include frame relay, asynchronous transfer mode (ATM) and optical fiber (instead of copper wire) – Bandwidth determined by fiber-optic cable class

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 60

Click to edit Master title styleWireless Ethernet (Wi-Fi)

• Most common wireless connection technology that is also called 802.11 – Latest version is 802.11ac with bandwidth ranges up

to 2.5 Gbps and a range of 500 feet – Speed impacted by objects the signals pass through

• Wireless access point (WAP) transmits packets between Wi-Fi-equipped computers and other devices within range – Devices capable of roaming or shifting from one WAP

to another without human intervention – Hot sports are WAPs open to the public

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 61

Click to edit Master title stylePersonal Area Networks (Piconets)

• Bluetooth is a low-bandwidth technology (722 Kbps) designed for personal use over short distances – Useful for wireless synchronization and printing – Devices consume very little power and can discover one

another and exchange information automatically • Ultra Wideband (UWB) provides bandwidth up to 480

Mbps and connections over short distances – Future personal area networking applications

• ZigBee is a low bandwidth technology with applications designed for energy management and remote controls for consumer electronics

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 62

Click to edit Master title styleFixed-Point Wireless

• Used in rural areas without cable service • System of repeaters used to forward radio signal

from ISP to customers • Repeaters are transmitter-receiver devices

(transceivers) • Uses mesh routing

– Directly transmits Wi-Fi packets through short-range transceivers (hundreds or thousands)

– Located close to each other

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Click to edit Master title styleSatellite Microwave

• Made connections to the Internet possible for the first time in many rural areas

• Use microwave transmitters that provide upload bandwidths in the range of 120 Kbps to 5 Mbps and downloads in the 1-16 Mbps range

• Installation cost has decreased due to improved technologies that allow self-installation

• Offered by airlines • Once the only wireless Internet access available,

but many other options now exist

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Click to edit Master title styleMobile Telephone Networks

• Number of mobile phones in 2014 (almost 8 billion) exceeded population for the first time in history

• Short message service (SMS) protocol – Send and receive short text messages

• Third-generation (3G) wireless technology – 2 Mbps download/800 Kbps upload speeds

• Fourth-generation (4G) technology – Long Term Evolution (LTE) and Worldwide

Interoperability for Microwave Access (WiMAX) offer 14 Mbps download/ 8Mbps upload speeds

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 65

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FIGURE 2-15 Internet connection options

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Click to edit Master title styleInternet2 and the Semantic Web

• Internet2 is an advanced research network created in 1996 as a replacement for ARPANET laboratory – Experimental networking technologies test bed – High end of the bandwidth spectrum (10 Gbps) – Used by universities, medical schools, CERN – Focus: mainly technology development

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Click to edit Master title styleInternet2 and the Semantic Web (cont’d.)

• Semantic Web project has a goal of blending technologies and information – Web pages tagged (using XML) with meanings – Uses software agents (intelligent programs) to read

XML tags, determine meaning of words • Resource description framework (RDF)

• Set of XML syntax standards – Development of Semantic Web will take many years

• Start with ontologies for specific subjects

© 2017 Cengage Learning®. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website or school-approved learning management system for classroom use. 68