Transcript 5.1 Introduction - Internet Entrepreneurship

Chapter 5, Internet Hardware,
Software and Communications
Outline
5.1
Introduction
5.2
Structure of the Internet
5.3
Hardware
5.3.1
Servers
5.3.2
Communications Media
5.3.3
Storage Area Networks (SANs)
5.4
Connecting to the Internet
5.4.1
Digital Subscriber Lines (DSL)
5.4.2
Broadband
5.4.3
Integrated Services Digital Network (ISDN)
5.4.4
T-1 and T-3 Lines
5.5
Internet2
5.6
Software
5.6.1
Application Service Providers (ASPs)
5.6.2
Databases
 2001 Prentice Hall, Inc. All rights reserved.
Chapter 5, Internet Hardware,
Software and Communications
Outline
5.7
Operating Systems
5.7.1
UNIX
5.7.2
Microsoft Windows
5.7.3
Linux
5.7.4
Mac OS X
5.8
Enhancing Business Communication
5.8.1
Intranets and Extranets
5.8.2
Streaming Audio and Video
5.8.3
Internet Telephony
5.8.4
Web Casting and Webconferencing
 2001 Prentice Hall, Inc. All rights reserved.
5.1 Introduction
•
•
•
•
•
Connection media
Cost of connecting
Streaming media (audio and video)
Internet telephony
Technologies used to enhance online business
communications
 2001 Prentice Hall, Inc. All rights reserved.
5.2 Structure of the Internet
• IP address (Internet Protocol)
– Computers use IP addresses to locate other computers on the
Internet
• Packet
– Source address, a destination address, sequencing
information, error-control information and the data to be
delivered to the destination address
• Router
– Used to move packets across the Internet efficiently
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5.3 Hardware
• The Internet employs many advanced hardware
technologies
– Various communications media used to connect hosts
– The roles hosts play on the Internet
• Servers
• Communications Media
• Storage Area Networks (SAN)
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5.3.1 Servers
• Server
– A host on the Internet that manages network resources and
fulfills requests from clients
– Web servers, e-mail servers, database servers and file servers
– A single server may provide multiple services
• A Web server stores Web pages and delivers the
pages to clients upon request
• Protocols for delivering information over the Web
–
–
–
–
Hypertext transfer protocol (HTTP)
File transfer protocol (FTP)
Post office protocol (POP)
Simple mail transfer protocol (SMTP)
 2001 Prentice Hall, Inc. All rights reserved.
5.3.2 Communications Media
• Communications medium
– The hardware that connects computers and other digital
equipment
• Bandwidth
– Indicates how much data can be transferred through the
medium in a fixed amount of time
– Usually measured in bits per second (bps)
• Copper wire
– The primary communications medium
 2001 Prentice Hall, Inc. All rights reserved.
5.3.2 Communications Media
• Fiber-optic cable
– Composed of flexible glass fiber, is thinner and lighter than
traditional copper wire, yet has much wider bandwidth
– Uses short bursts of light to represent bits
• Optical modem
– Modem stands for modulator and demodulator
– Translates digital signals from computers into light through a
process called modulation
• Opto chip
– Converts the most basic particle of light, the photon, into an
electric current
– Allows tremendous amounts of data to be sent over fiberoptic networks through particles 100 times smaller than the
diameter of a human hair
 2001 Prentice Hall, Inc. All rights reserved.
5.3.2 Communications Media
• The strength of a signal transmitted over a
communications medium is reduced as the signal
travels farther and farther
• Repeater
– Can be used to alleviate this problem by amplifying and
retransmitting the signal across segments of copper wire or
fiber-optic cable
• Transmission costs
– Fiber-optic cable is more expensive than copper wire
– Installation of fiber-optic cable is more complicated than
installation of copper wire
– Fiber-optic cable requires fewer repeaters
 2001 Prentice Hall, Inc. All rights reserved.
5.3.3 Storage Area Networks
• Companies produce large volumes of data to
support sales analysis tools, enterprise resource
planning (ERP) systems, multimedia Web sites
and e-commerce systems
• Storage Area Network (SAN)
– Provides high-capacity, reliable data storage and delivery on
a network
– Allows network administrators to collect data in logical
groups on data servers distributed throughout the network
– SAN devices store large volumes of data and may also
provide backup and recovery services
 2001 Prentice Hall, Inc. All rights reserved.
5.3.3 Storage Area Networks
• Mirroring technology
– A SAN device stores redundant copies of data, so that if one
copy is lost or damaged, a mirrored copy can be used
• Fiber-channel technology
– A high-speed communications medium based on fiber-optic
technology that provides transfer rates of 100 Mbps
• Network storage devices providers
– EMC
– Compaq
– StorageNetworks
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5.4 Connecting to the Internet
• Most home users subscribe to an Internet Service
Provider (ISP) to connect to the Internet
– Some charge fixed monthly fees for Internet access
– Some offer free Internet access in return for personal
demographic data
• Analog modem
– User connects to an ISP using the modem, which then
connects the user to the Internet
– Takes digital signals from the computer and turns them into
analog signals
• Analog signals can be transmitted over a telephone line just
like a human voice
– A modem at the ISP then converts the sound back into a
digital signal that can be transmitted over the Internet
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5.4 Connecting to the Internet
• Free Internet access providers
– NetZero
– IsFree.com
– ACI
– Address.com
• Web TV
– A low-cost technology for connecting to the Internet through
the user’s television, instead of a PC
– WebTV users can dial into an ISP through a modem to surf
the Web, send and receive e-mail and chat with other people
– The basic WebTV system includes a wireless keyboard, an
8.6-GB, a hard drive and a 56-Kbps modem
 2001 Prentice Hall, Inc. All rights reserved.
5.4.1 Digital Subscriber Lines
• Digital Subscriber Lines (DSL)
– Offers high-bandwidth Internet access over existing copper
telephone lines
– Splits your phone line into three information-carrying
channels
– DSL connections require special hardware at the local
telephone company’s central office and at the user’s location
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5.4.1 Digital Subscriber Lines
• IAD (integrated access device)
– Provides network connections for high-speed Internet
access, as well as connections for multiple voice telephone
lines
• ADSL (asymmetric DSL)
– the connection speed for sending data to the Internet
(upstream) is slower than the connection speed for receiving
data from the Internet (downstream)
• VoDSL (voice over DSL)
– Provides voice telephone services and high-speed data
access over a single standard telephone line
• SDSL (symmetric DSL)
– Transfers data at the same speed both upstream and
downstream
 2001 Prentice Hall, Inc. All rights reserved.
5.4.1 Digital Subscriber Lines
Metho d
Sp eed (Kb p s) Send Sp eed = Co st
Rec eive
Sp eed
Ava ila b ility fo r
Businesses
Modem
33–56
No
Very low
Universal
Cable modem
ISDN
xDSL
64–1500
56–128
384–55,000
No
Yes
No
Medium
High
Low
Very limited
Widely available
Limited
Frame relay/T1
64–1544
Yes
Very high
Widely available
Fig. 5.1 Internet c o nnec tio n c o m p a riso n c ha rt. (Co urtesy o f GLINK, LLC.)
 2001 Prentice Hall, Inc. All rights reserved.
5.4.2 Broadband
• Broadband
– A category of high-bandwidth Internet service provided
mainly by cable television and telephone companies to home
users
– Can handle voice, data and video information
– Enables videoconferencing, real-time voice and streamingmedia applications
– Always connected, eliminating the need to dial into an ISP
• Cable modem
– Translates digital signals for transmission over the same
cables that bring cable television to homes and businesses
– Connections is shared among many users
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5.4.3 Integrated Services Digital
Network (ISDN)
• ISDN (Integrated Services Digital Network)
– Provides high-speed connections to the Internet over both
digital and standard telephone lines
– Limited service
– Costly connection
– Divided into three channels that each perform different tasks
• Two bearer channels each support data transfers, while the data
channel is used to transmit routing information
– ISDNZone
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5.4.4 T-1 and T-3 Lines
• T-1 line
– A dedicated connection that supports data rates of 1.544 Mb
per second
– Made up of 24 channels
• T-3 line
– Supports data rates of 43Mbps and is made up of 672
channels that each support 64Kbps
• T-1 and T-3 lines can be used for both voice and
data communication
• Everythingt1.com
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5.5 Internet2
• Consortium developing next generation of the
Internet
– Abeline
• A high-speed network currently used by Internet2 consortium
members, will soon be able to transfer 2.4 gigabits of data per
second
– Teleimmersion
• Allows users in different locations to share information in real
time—even 3D images
– Virtual laboratory
• Enable researchers worldwide to collaborate on projects
– Digital libraries
• Storage of audio and video files, enabling a search for a movie
by a line from its soundtrack.
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5.6 Software
• Application Service Providers
• Databases
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5.6.1 Application Service Provider
• Provide customized business software applications
over the Internet
• Maintains and updates the application as necessary
• Companies can eliminate the costs associated with
developing and maintaining business applications
• Virtual private networks (VPNs)
– Allow customers to connect to their applications securely
over the Internet
– VPNs use the point-to-point tunneling protocol (PPTP) to
create a secure channel of communication between the
customer and the ASP
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5.6.2 Databases
• Database
– An integrated collection of data
• Database management system (DBMS)
– Provides mechanisms for storing and organizing data in a
manner that facilitates satisfying sophisticated queries and
data manipulations
• Structured Query Language (SQL
– Almost universally used with relational database systems to
make queries (i.e., to request information that satisfies given
criteria) and manipulate data
 2001 Prentice Hall, Inc. All rights reserved.
5.6.2 Databases
• Relational database model
– A logical representation of the data that allows the
relationships between the data to be considered
independently of the physical implementation of the data
structures
• Popular enterprise-level relational database
systems:
–
–
–
–
–
Microsoft Sequel Server
Oracle
Sybase
DB2
Informix
 2001 Prentice Hall, Inc. All rights reserved.
5.7 Operating Systems
• Operating system (OS)
– Software that manages the resources on a computer
– Multiuser OS
• Allows more than one user to run programs simultaneously
– Multiprocessor OS
• Controls a computer that has many hardware CPUs
– Multitasking OS
• Allows multiple applications to run simultaneously
– Multithreading OS
• Allows an individual program to specify that several activities
should be performed in parallel
• Major operating systems used in desktop
computers are UNIX , Linux , Macintosh and
Windows
 2001 Prentice Hall, Inc. All rights reserved.
5.7.1 Unix
• Multics
– “All things to all people”
– Bell Laboratories, General Electric and Project MAC
• Unix
– Developed by Bell Laboratories after leaving the Multics
project
– First version written in assembly language
– Unique design and coherence
– Met the needs of programmers who were building software
and of administrators who control software development
efforts
 2001 Prentice Hall, Inc. All rights reserved.
5.7.1 Unix
• University of California at Berkley
– From time sharing to systems appropriate for studying
distributed computing environments
• Sun Microsystems
– Sun OS
– Include facilities for supporting a graphics, window-based,
mouse-oriented interface
– Provided facilities for diskless workstations to use the
network for file storing, sharing and paging
• The Open Group
– Controls the specification for UNIX and holds the trademark
– www.unix-systems.org
 2001 Prentice Hall, Inc. All rights reserved.
5.7.2 Microsoft Windows
• The most popular operating system in the world
• Introduced in 1984 with graphical user interface
(GUI) added to the DOS system
• Windows 2.0
– Failed to make a large impact in the market
– Took too long to open applications, change screens, etc.
• Windows 3.0
– Achieved widespread success
• Windows 95
– Introduced a new graphical user interface and increased
performance
• Windows 98, Windows NT and Windows 2000
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5.7.3 Linux
• Linux
– A UNIX-like operating system that has been developed by
volunteers worldwide
– Initially developed by Linus Torvalds
– Greatest success on the server-side
• Version 1.0
– Released in 1994, gained market share to become one of the
world’s most widely used operating systems
• The Gnome Foundation
– Founded to develop a free Linux-based desktop environment
and a free application framework to compete with Microsoft
Office for the desktop-computer environment
 2001 Prentice Hall, Inc. All rights reserved.
5.7.3 Linux
• Open source software
– Freely available source code, so that anyone can use, customize
and make updates to the software
• Kernel
– The core of the operating system
• Most of the applications that run on Linux are freely
available over the Internet and on many CD-ROM
distributions
• GNU General Public License (GPL)
– One of the most widely used open-source licenses
– Requires that the source code for GPL-licensed software, as well
as the source code for any modifications or improvements to that
software, is made freely available to the public
 2001 Prentice Hall, Inc. All rights reserved.
Microsoft.NET
• Microsoft.NET
– Weaves together the operating system, the Internet and each
device to create applications and services to be accessed
anytime, anywhere, from any device
– Could potentially support UNIX and Linux
• Building and maintaining .NET components
–
–
–
–
•
Windows.NET
Visual Studio.NET
Integrated development environment (IDE)
.NET Enterprise Servers and the .NET framework
.NET applications will be built with XML
 2001 Prentice Hall, Inc. All rights reserved.
5.7.4 Mac OSX
• Achieved great success in the 1980s, dominating
the market for GUI-based personal computers
• One of the first widely available systems to use a
window-based (i.e., a GUI) interface, a mouse and
icons
• Release of Windows challenged MacIntosh sales
• Mac OS X operating system
– Core was built using industry open standards based on Unix
• Aqua
– New Mac OS X interface
 2001 Prentice Hall, Inc. All rights reserved.
Internet Appliances
• Internet appliances
– Desktop devices designed specifically for connecting to the
Internet
– iPAQ Home Internet Appliance
– Netpliance i-opener
• Devices allow you to browser the Web, send and
receive e-mail and access streaming media online
• Limited functionality
 2001 Prentice Hall, Inc. All rights reserved.
5.8 Enhancing Business
Communication
•
•
•
•
Intranets
Extranets
Streaming audio and video
Internet telephony
– Makes PC-to-PC and PC-to-phone calls possible,
dramatically reducing the cost of communication
• Web casting
• Virtual conferencing
• Wireless technology
 2001 Prentice Hall, Inc. All rights reserved.
5.8.1 Intranets and Extranets
• Intranet
– An organization’s internal network that uses the TCP/IP
protocols of the Internet
– Only authorized parties, such as the organization's
employees, have access to an organization’s intranet
– Used to store internal information
• Extranet
– An intranet that is also accessible by authorized external
parties who are not members or employees of the
organization
– Members or employees might have unrestricted access to
information on the extranet, whereas customers or vendors
might have access to a limited subset of that information
 2001 Prentice Hall, Inc. All rights reserved.
5.8.2 Streaming Audio and Video
• Streaming technologies
– Allow users to send and process audio and video data
continuously
– Allows users to start playing the audio or video file while it
is still downloading
– Users can play music over the Internet
– Users can watch a small video on a Web site
 2001 Prentice Hall, Inc. All rights reserved.
5.8.2 Streaming Audio and Video
RealPlayer dialog. (Copyright© 1995-2000 Realnetworks, Inc. All Rights Reserved. RealNetworks,
Real.com, RealPlayer are trademarks registered trademarks of of RealNetworks, Inc.)
 2001 Prentice Hall, Inc. All rights reserved.
5.8.3 Internet Telephony
• Internet telephony
– Enables communication over the Internet, allowing you to
use your PC as a telephone
– Cost efficient
• Net2Phone
– Service allows you to make free PC-to-telephone calls
within the United States, and international calls at
discounted rates
– Net2Phone and other Internet telephony services are not
always compatible with systems running firewalls
– ClickTogether service allows companies to add personalized
voice capabilities to a Web site
 2001 Prentice Hall, Inc. All rights reserved.
5.8.4 Webcasting and Web
Conferencing
• Webcasting
– Broadcasting over the Web
– Businesses can stream seminars, conferences, shows, sales
presentations and more though their Web sites
– Live or prerecorded
• Web conferencing
– Allows businesses to meet and collaborate online, in real
time from anywhere in the world
• Evoke
– Webcasting and Web conferencing
 2001 Prentice Hall, Inc. All rights reserved.