Good Morning!
Jody Gillis
jgillis@rrc.mb.ca
949-8401
http://xnet.rrc.mb.ca/jodyg
Topics Session #1
Basic Telecommunication Concepts
Telecommunication Models
Networking
Client/server Computing
Telecommunication Standards
Wireless Communications
Internet
Modems
Baud - transfer rate (bits per second)
Analog signals: continuous
Digital signals: discrete
Modulation: translating digital data to analog
Demodulation: translating analog data to digital
Modems modulate & demodulate data
Fax/Modem
telephone as well as facsimile
Modems
A telephone line can only accommodate an
analog signal (a signal continuous in time and
amplitude)
A computer generates a digital signal
representing bits
Modem: a device that translates data from
digital to analog and analog to digital
Figure 6.8: How a Modem Works
Multiplexers
See HowStuffWorks.com
(telephone, modem, …)
Multiplexers: devices that allow several
telecommunications signals to be transmitted
over a single communications medium at the
same time
Figure 6.9: Use of a Multiplexer to
Consolidate Data Communications onto a
Single Communications Link
Front-End Processors
Front-end processors: special-purpose computers
that manage communications to and from a
computer system
Connect a midrange or mainframe computer to
hundreds or thousands of communications lines
Figure 6.10: Front-End Processor
Telecommunications Media
Types of Media
Twisted Pair
Coaxial Cable
Fiber-Optic Cable
Microwave Transmission
Twisted Pair
Fig 6.4
Coaxial Cable
Fig 6.5
Fiber Optic Cable
Fig 6.6
Wireless Technologies
RF
802.11 standards (WiFi)
Bluetooth
Cellular communications
Microwave
Infrared
Use in Mobile Computing Devices
Microwave Transmission
Fig 6.7
Satellite
Fig 6.8
Cellular
Fig 6.9
Local Area Networks
Server Based (Novell/Microsoft Windows-NT)
Peer-to-Peer (LANtastic, Windows NT)
Lan Topology
Star
Bus
Ring
Hierarchical
Wikipedia article
What Is Client/Server?
Client/server is a term used to describe a computing
model for the development of computerized systems.
This model is based on the distribution of functions
between two types of independent and autonomous
processes; servers and clients.
A client is any process that requests specific services
from server processes.
A server is a process that provides requested services
for clients.
The key to client/server power is where the requested
processing takes place.
What Is Client/Server?
Basic Client/Server Computing
The Forces That
Drive Client/Server Systems
Changing Business Environment
Global competition.
Need for fast, efficient, and widespread data access.
Need for Enterprise-Wide Data Access
End User Productivity Gains Based on the Use
of Data Resources
Technological Advances
Microprocessor technology, Data communications and LANs,
DB systems, OS and GUIs, Sophisticated PC-based end user
application software.
Cost/Performance Advantages of the PC-Based
Platform
The Evolution of Client/Server IS
Mainframes in the 1970s
Complex, proprietary OS
Dumb terminals
Restricted access
Hardware and software dictated IS
Centralized, complex MIS department bureaucracy
Microcomputers in the 1980s
Easy-to-use software (e.g., spreadsheet)
Micro-based database systems
Data still in mainframes
“Manual download”
The Evolution of Client/Server IS
Intelligent Terminals
PCs connected to the mainframe
Electronic download
Proliferation of snapshot versions of corporate DB
Islands of information
Sneaker net
Local Area Network
Network operating systems (NOS)
Powerful PCs
Common platform for both end users and MIS
specialists
Client/Server Systems Benefits
Client/Server Benefits
Platform-independent system development
Optimized distribution of processing activities among
different platforms
Use of user friendly, cost effective, and compatible
techniques, methodologies, and specialized tools
Managerial Expectations of
Client/Server Systems Benefits
Organizational Expectations of Client/Server
Benefits
Flexibilityand adaptability
Improved employee productivity
Improved company work flow and a way to re-
engineer business operations
New opportunities to provide competitive
advantages
Increased customer service satisfaction
Client/Server Architecture
Components of Client/Server Architecture
Client. The client is any computer process that requests
services from the server. It is also known as the front-end
application.
Server. The server is any computer process providing
services to the clients. The server is also known as the
back-end application.
Client/Server Architecture
Client Components
Powerful hardware
An operating system capable of multitasking
A graphical user interface (GUI)
Communications capability
Client/Server Architecture
Server Components
Fileservices
Print services
Fax services
Communications services
Database services
Transaction services
Miscellaneous services
The Internet, Intranets, and Extranets
Telecommunication Standards
TCP/IP Transmission Control Protocol/Internet
Protocol
standardized naming conventions .com .edu .gov
.org
Integrated Services Digital Networks (ISDN)
transmission of voice, data, and video on the same
line (two 64KB channels & one 16KB channel)
Use and Functioning
of the Internet
What is the Internet
a global set of interconnected data networks
running the TCP/IP protocols
Traditional services include email, file transfer
(FTP); current focus is on the World Wide Web
Organizations:
W3C
ICANN
Canada (.ca): CIRA
How the Internet Works
Hosts
Routers forward packets to other networks
Internet Protocol Stack (TCP/IP)
Protocol (IP)
Internet
Transport Control Protocol (TCP)
Backbones
See Intro to Internet notes
How the Internet Works
Uniform Resource Locator(URL)
http://www.whitehouse.gov
World Wide Web Domain category
Hypertext
Host Network Name
transfer protocol
Table 7.1
Figure 7.3: Several Ways to
Access the Internet
Structure of the Internet
National/global backbone networks
Network Access Points (NAPS) connecting the
major commercial backbones
Internet Service Providers (ISPS)
“wholesale”:selling access to Users and other ISPS
“retail”:resell access to someone else's backbone
The World Wide Web
The World Wide Web
World Wide Web: a.k.a. the Web, WWW, or W3
A menu-based system that uses the client/server
model
Organizes Internet resources throughout the
world into a series of menu pages, or screens,
that appear on your computer
Hypermedia: tools that connect the data on Web
pages, allowing users to access topics in
whatever order they wish
The World Wide Web (continued)
Hypertext Markup Language (HTML): the
standard page description language for Web
pages
HTML elements (tags): inform browsers how to
format text on a Web page, and whether images,
sound, and other elements should be inserted
Extensible Markup Language (XML): markup
language for Web documents containing
structured information, including words,
pictures, and other elements
Html and XML Demo
Web Software
Web browsers
Search engines
Keyword indexes: fast & broad
Subject indexes: focused searches
Internet Services
Web Services
Web services: standards and tools that
streamline and simplify communication among
Web sites for business and personal purposes
XML is used within a Web page to describe and
transfer data between Web service applications
Web Services (continued)
Besides XML, other components are used in
Web service applications:
SOAP (Simple Object Access Protocol)
WSDL (Web Services Description Language)
UDDI (Universal Discovery Description and
Integration)
Internet and Web Applications
E-mail and instant messaging
Instant messaging: a method that allows two or
more individuals to communicate online using
the Internet
Internet cell phones and handheld computers
Internet and Web Applications
(continued)
Web log (blog): a Web site that people can
create and use to write about their observations,
experiences, and feelings on a wide range of
topics
Usenet and newsgroups
Usenet: a worldwide internet discussion system.
News readers (often built into email client software)
are used to view postings.
Newsgroups: online discussion groups that focus on
specific topics
Example: Google Groups
Internet and Web Applications
(continued)
Chat room: a facility that enables two or more
people to engage in interactive “conversations”
over the Internet
Internet phone and videoconferencing services
Content streaming: a method for transferring
multimedia files over the Internet so that the
data stream of voice and pictures plays more or
less continuously without a break, or very few of
them; enables users to browse large files in real
time
Fig 6.24
Figure 7.7: How Voice Over IP Works
Internet and Web Applications
(continued)
Web auctions
Music, radio, and video on the Internet
Office on the Web
Internet sites in three dimensions
Free software and services
Electronic Payment Methods
Components
Broad acceptance
Payment input mechanisms
Point of sale readers, smart cards, PCs
Online payments
Paypal
Online Checks
New Organizations
are Emerging
Increasing usage of consultants,
temporary/contract/term employees
Telecommuting and flexible schedules becoming
more commonplace
Table 7.6: Summary of Internet and
Web Applications
Table 7.6: Summary of Internet and
Web Applications (continued)
Intranets and Extranets
Intranets and Extranets
Intranet
Internalcorporate network built using Internet and
World Wide Web standards and products
Slashes the need for paper
Provides employees with an easy and intuitive
approach to access information that was previously
difficult to obtain
Intranets and Extranets (continued)
Extranet: a network based on Web technologies
that links selected resources of a company’s
intranet with its customers, suppliers, or other
business partners
Virtual private network (VPN): a secure
connection between two points across the
Internet
Tunneling: the process by which VPNs transfer
information by encapsulating traffic in IP
packets over the Internet
Table 7.11: Summary of Internet,
Intranet, and Extranet Users
Figure 7.8: Virtual Private Network
Net Issues
Net Issues
Management issues: preventing attacks
Service and speed issues
Web server computers can be overwhelmed by
the amount of “hits” (requests for pages)
DoS attacks
Routers can become bottlenecks
Figure 7.9: Typical Sources of
Internet Attacks
Net Issues (continued)
Privacy
Spyware: hidden files and information trackers that
install themselves secretly when you visit some
Internet sites
Cookie: a text file that an Internet company can
place on the hard disk of a computer system
Fraud
Phishing, (Phreaking, Pharming, etc.)
Net Issues (continued)
Security with encryption and firewalls
Cryptography: converting a message into a secret
code and changing the encoded message back to
regular text
Digital signature: encryption technique used to
verify the identity of a message sender for
processing online financial transactions
Firewall: a device that sits between an internal
network and the Internet, limiting access into and
out of a network based on access policies
Figure 7.10: Cryptography process
Internet Security
Malware
Viruses
Spyware
Adware
Keyloggers
Horses
Trojan
Worms (i.e. Conficker)