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Technology In Action Chapter 12
Review: Database
• Electronic collections of related data
• Help us organize data
• Turn data into information
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Technology In Action Chapter 12
Advantages of Using Databases
• Store and retrieve large quantities of
information
Recording grades
Financial Aid
• Data centralization
• Data integrity
Student Registration
• Flexibility
Student
Information
Student housing Database
Parents
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Technology In Action Chapter 12
Database components
• Field
– Data type: text, numeric, date, object, hyperlink…
• Record
• Table
– Primary key
– Foreign key (referential integrity)
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Technology In Action Chapter 12
Database Types
• Relational database
• Object-oriented database
• Object-relational database
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Technology In Action Chapter 12
Database Management Systems
(DBMS)
• Application software designed to acquire
and analyze data
• Microsoft Access, Oracle
• Four main operations of a DBMS are:
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–
–
–
Creating databases and entering data
Viewing and sorting data
Extracting or querying data (SQL)
Outputting data
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Technology In Action Chapter 12
Managing Data:
Information Systems
• Office support systems (OSS)
– Microsoft Office
• Transaction processing system (TPS)
• Management information system (MIS)
• Decision support systems (DSS)
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Technology In Action Chapter 12
Technology In Action
Chapter 12 & 13
Behind the Scenes:
Networking and Security
The Internet: How it Works
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Technology In Action Chapter 12
Ch.12 Topics
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•
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Advantages of a network
Client/server and peer-to-peer networks
Classifications of client/server networks
Client/server network components
Moving data in a client/server network
Securing networks
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Technology In Action Chapter 12
Network
• Definition (Ch.7)
• Advantages:
– Increase productivity
– Enable the sharing of resources
– Facilitate Internet connectivity
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Technology In Action Chapter 12
Two architectures
Peer-to-Peer
Client/Server
Every node communicates
with every other node
All nodes communicate
through the server
Used for fewer than 10 users
Used for more than 10 users
Not easily scalable
Easily scalable
Decentralized
Centralized
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Technology In Action Chapter 12
Client/Server Networks
• Server based network:
– Clients
– Servers
• Servers respond to
requests from clients
• Servers perform
specific tasks
• Scalable network
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Technology In Action Chapter 12
Classifications of Client/Server
Networks
• LAN:
– Local area network
• WAN:
– Wide area network
• MAN:
– Metropolitan area network
– Computers linked together within a city or county
• PAN
– Personal area network
• Intranet
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Technology In Action Chapter 12
Constructing Client/Server
Networks
•
•
•
•
•
•
Servers
Network topologies
Transmission media
Network operating system (NOS)
Network adapters
Network navigation devices
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Technology In Action Chapter 12
Servers
• Number and type of servers depend on
network size and workload
• Dedicated server:
– Perform one specific function
• Examples:
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–
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–
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Authentication server
File server
Printer server
Database server
Email server
Web server
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Technology In Action Chapter 12
Network Topologies
• The physical layout of computers,
transmission media, and other
components
• Types of network topologies include:
– Bus topology
– Ring topology
– Star topology
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Technology In Action Chapter 12
Bus Topology
• All nodes are connected
in sequence on a single
cable
• Used most often on
peer-to-peer networks
• Networked computers
communicate with each
other
• One computer transmits
data at a time:
– Access methods avoid data
collisions
– Data is transmitted in
“packets”
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Technology In Action Chapter 12
Ring Topology
• Nodes are laid out in
a ring
• Token (data packet)
flows in one direction
from device to device
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Technology In Action Chapter 12
Star Topology
• Nodes connect to a
central communications
device (hub/switch)
• A node sends a signal to
the hub which
retransmits it to the
other nodes
• A node accepts the
signal addressed to it
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Technology In Action Chapter 12
Transmission Media
• The routes data takes to flow between
devices on a network:
• Wired
– Twisted pair cable
– Coaxial cable
– Fiber-optic cable
• Wireless:
– Wireless Fidelity (Wi-Fi)
– Uses radio waves
– 802.11 standard
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Technology In Action Chapter 12
Choosing a Cable
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Maximum run length
Bandwidth
Bend radius
Cable cost
Installation costs
Susceptibility to
interference
• Signal transmission
methods
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Technology In Action Chapter 12
Network Operating Systems (NOS)
• Provide the protocol that controls the
communication between devices on the
network
• Major network operating systems:
– Windows Server 2003
– UNIX
– Novell NetWare
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Technology In Action Chapter 12
Network Adapters
• Devices that enable computers to
communicate on a network
• Network interface cards (NICs):
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Generate network transmission signals
Create data packets
Act as information gatekeepers
Ethernet compliant
Wireless NICs
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Technology In Action Chapter 12
Network Navigation Devices
• Media Access Control (MAC) address:
– Six 2-digit numbers (01:40:87:44:79:A5)
– Physical address of network adapter
– Internal network identification
• Repeaters and Hubs:
– Amplify signals and retransmit them
• Switches and Bridges:
– Send data on a specific route through the network
– Bridges send data between collision domains
• Routers:
– Send information between two networks
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Technology In Action Chapter 12
Network Security
• Authentication:
– User ID and password used to access the network
• Access privileges:
– Enable access to certain network systems
• Physical protection measures:
– Restrict physical access to sensitive network
equipment
– Magnetic card readers
– Biometric access devices
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Technology In Action Chapter 12
Network Security
• Firewalls:
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–
–
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Prevent access to the network by unauthorized users
Composed of software and/or hardware
Screens and validates data packets
Bastion host/proxy server
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Technology In Action Chapter 12
Network Firewall Layout
Firewall
Perimeter
Network
Internal
Network
External
Screening
Router
Bastion Host
/Proxy Server
Internal
Screening
Router
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Technology In Action Chapter 12
Chapter 12 Summary Questions
• How does a client/server network differ
from a peer-to-peer network?
• What are the different classifications of
client/server networks?
• What components are needed to construct
a client/server network?
• What are the various network topologies?
• What types of transmission media are
used in client/server networks?
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Technology In Action Chapter 12
Ch. 13 Topics
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Managing the Internet
Interaction between Internet components
IP addresses and domain names
Data transmission and protocols
HTML and XML
E-mail and instant messaging
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Technology In Action Chapter 12
Management of the Internet
Who owns the
Internet?
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Individuals
Universities
Government agencies
Private companies
Who pays for the
Internet?
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US taxpayers
Businesses
Universities
Other countries
Who manages the
Internet?
– Nonprofit
organizations
– User groups
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Technology In Action Chapter 12
Internet Networking
• A network of networks:
– Worldwide network of computer systems
– Communications protocols
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•
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•
Network hierarchy
T lines
Network access points
Points of Presence
The network model
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Technology In Action Chapter 12
Network Hierarchy
• Tier 1:
– The Internet backbone
– Moves large amounts of data
– Provide access to Regional ISPs
Tier 3 ISP
Tier 2 ISP
• Tier 2:
– Regional ISPs
– Provide access to local ISPs
• Tier 3:
– Local ISPs
– Provide Internet access to homes
and businesses
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Technology In Action Chapter 12
T Lines
• High speed fiber-optic lines
• T-1 line:
– 24 simultaneous voice or data channels
– 1.544 Mbps throughput
• T-2 lines:
– 4 T-1 lines
– 6.3 Mbps throughput
• T-3 lines:
– 28 T-1 lines
– 44.76Mbps throughput
• T-4 lines:
– 168 T-1 lines
– 247.176 Mbps throughput
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Technology In Action Chapter 12
Network Access Points (NAPs)
• Points of connection between ISPs
• Routers move data between networks
Tier 1
ISP
Routers
Tier 2
ISPs
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Routers
Routers
Tier 2
ISPs
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Technology In Action Chapter 12
Points of Presence (POP)
• Bank of modems where individual users
connect to an ISP
Other
computers
Your ISP
Your computer
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Point of
Presence
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Technology In Action Chapter 12
Network Model
• Internet communications follows the client/server
network model
• Clients request services
• Servers respond to requests
• Types of servers include:
– Web servers:
 Host Web pages
– Commerce servers:
 Enables the purchase of goods and services over the
Internet
– File servers:
 Provide remote storage space for files that users can
download
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Technology In Action Chapter 12
Animation: Network Model
4.
Click to view
animation. Click
once only.
Network Access
Point (NAP)
2. Your request
1. goes
Youtorequest
your ISP’sa
point
of presence
Web
page.
Your request
goes to the
National
Backbone
Network
National Backbone
Network
(POP).
5.
Your request
goes to the Web
site’s server
3.
Your request
goes to a Network
Access Point
YOU ARE
HERE
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ISP’s Point of
Presence (POP).
The Web page is
sent back to you
in packets.
Web site’s server
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Technology In Action Chapter 12
Data Transmission and Protocols
• Computer protocols are rules for electronic
information exchange
• Open system protocols:
– Any computer can communicate with other computers
using the same protocols
• Circuit switching
• Packet switching
• TCP/IP
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Technology In Action Chapter 12
Circuit Switching
• Dedicated connection between two points
• Remains active until the transmission is
terminated
• Telephone communications
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Technology In Action Chapter 12
Packet Switching
• Data is broken into small units called
packets
• Packets are sent over various routes to
their destination
• Packets are reassembled by the
receiving computer
• Packets contain:
– Destination/source addresses
– Reassembling instructions
– Data
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Technology In Action Chapter 12
Animation: Packet Switching
ISP New York
WebPackets
Page
Data
01 02 03 04 05 06
07 08 09 10 11 12
Your ISP
07 08 09 10 11 12
13 14 15 16 17 18
19 20 21 22 23 24
25 26 27 28 29 30
Click to view
animation
ISP Virginia
ISP Florida
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Your
Computer
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Technology In Action Chapter 12
TCP/IP
• Transmission Control Protocol (TCP):
– Prepares data for transmission
– Provides error checking
– Enables resending lost data
• Internet Protocol (IP):
– Responsible for sending data from one computer to
another
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Technology In Action Chapter 12
IP Addresses
• Unique number that identifies devices
connected to the Internet
• Typical IP address:
– 197.24.72.157
• Static address:
– Address never changes
• Dynamic address:
– Temporary address
• Dynamic Host Configuration Protocol
(DHCP)
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Technology In Action Chapter 12
Domain Names
• Name that takes the place of an IP address
• Sample domain name:
– www.mywebsite.com
• Top level domains (TLD):
– Portion of the domain name that follows the period (dot)
– Sample top level domain names:
 .com; .org; .edu; and .net
• Second-level domains:
– Unique name within a top level domain
– Sample second-level domain names:
 Yahoo.com; Google.com; and Unesco.org
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Technology In Action Chapter 12
Other Protocols
• File Transfer Protocol (FTP):
– File sharing protocol
– Files are downloaded and uploaded using the Internet
– ftp://garbo.uwasa.fi
• Telnet:
– Protocol for connecting to a remote computer and a
TCP/IP service
– Enables a client computer to control a server
computer
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Technology In Action Chapter 12
HTTP and SSL
• Hypertext Transfer Protocol:
– Protocol for transferring hypertext documents
– Hypertext documents are linked to other documents
 Hyperlink
• Secure Socket Layer:
– Security protocols that protect sensitive information
– Encrypts data
– https://
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Technology In Action Chapter 12
HTML
• Hypertext Markup Language:
– Format for creating Web pages
– Not a programming language but a set of rules for marking up
text
HTML
Web Page
<h1>This is the Heading</h1>
<p><font face="Arial">This is text using Arial
font.</font></p>
<p><font face="Arial"><i>This text is
italicized</i>.</font></p>
<p><font face="Arial"><b>This text is
bold</b>.</font></p>
<p><font face="Arial"><font
color="#FF0000">This text color is
red</font>.</font></p>
<p><font face="Arial">This is a hyperlink <a
href="http://vig.prenhall.com/">
www.prenhall.com</a></font></p>
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Technology In Action Chapter 12
Common Gateway Interface (CGI)
• Browsers request that a program file
executes (runs)
• Adds Web page interaction:
– Adding names to guest books/mailing lists
– Completing forms
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Technology In Action Chapter 12
Client-Side Application
• A program that runs on a client computer
with no interaction with the server
• Types of client-side applications include:
– HTML document embedded with JavaScript code
– Applet:
 Small program that resides on the server
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Technology In Action Chapter 12
Extensible Markup Language
(XML)
• Designed for information exchange
• Tools used to create your own markup
language
• Used in e-commerce transactions
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Technology In Action Chapter 12
Communications Over the Internet
• E-mail:
– Created in 1971 by Ray Tomlinson
– Simple Mail Transfer Protocol (SMTP)
– Multipurpose Internet Mail Extensions (MIME)
 Protocol for attaching files to e-mail
• E-mail security:
– Encryption:
 Private-key encryption
 Public-key encryption (128-bit key)
– Secure data transmission software
 SafeMessage
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Technology In Action Chapter 12
Instant Messaging (IM)
• Client/server application program for realtime, text based conversations
• Popular instant messaging programs:
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–
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AOL Instant Messenger
ICQ
Yahoo! Messenger
Windows Messenger
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