Transcript 11. Building Information Systems

Chapter 4
Telecommunications, the Internet,
Intranets, and Extranets
An Overview of Telecommunications
 Telecommunications: the electronic transmission
of signals for communications
 Telecommunications medium: anything that
carries an electronic signal and interfaces
between a sending device and a receiving device
Telecommunications System Components
Channel Bandwidth
 Telecommunications professionals consider the
capacity of the communications path or channel
when they recommend transmission media for a
business
 Channel bandwidth: the rate at which data is
exchanged over a communication channel
 Usually measured in bits per second (bps)
Types of Signals
Analog signal

Continuous waveform

Passes through communications medium

Used for voice communications
Digital signal

Discrete waveform -- Transmits data coded into two
discrete states as 1-bits and 0-bits

Used for data communications
Modem

Translates computer’s digital signals into analog and vice
versa
Communications Media
Telecommunications Hardware
Table 4.3: Common Telecommunications Devices
Services
 Digital subscriber line (DSL): telecommunications
service that delivers high-speed Internet access to
homes and small businesses over the existing phone lines
of the local telephone network
 All major long distance carriers offer wireless
telecommunications services that enable you to place
phone calls or access the Internet
Networks and Distributed Processing
 Computer network: the communications media,
devices, and software needed to connect two or
more computer systems and/or devices
 Network nodes: the computers and devices on
the networks
Network Types
 Personal area network (PAN)
 Local area network (LAN)
 Metropolitan area network
(MAN)
 Wide area network (WAN)
 International networks
 Mesh networking
Distributed Processing
 Centralized processing: all processing occurs in a single
location or facility
 Decentralized processing: processing devices are placed
at various remote locations
 Distributed processing: computers are placed at remote
locations but connected to each other via a network
Client/Server Systems
 Client/Server system: multiple computer
platforms are dedicated to special functions,
such as database management, printing,
communications, and program execution
Communications Software and Protocols
 Communications protocol: a set of rules that govern the
exchange of information over a communications channel
 Protocols govern several levels of a telecommunications
network, such as:
 Hardware device level
 Application program level
Wireless communications protocols are still
evolving as the industry matures
Communications Software
Network operating system (NOS):
systems
software that controls the computer systems and
devices on a network and allows them to communicate
with each other
 Network-management software: software that a
manager uses on a networked desktop
 Monitors the use of individual computers and shared hardware
(such as printers)
 Scans for viruses
 Ensures compliance with software licenses
Use and Functioning of the Internet
 Internet: a collection of interconnected networks, all
freely exchanging information
 ARPANET
 The ancestor of the Internet
 A project started by the U.S. Department of Defense (DoD) in
1969
 Internet Protocol (IP): communication standard that
enables traffic to be routed from one network to
another as needed
How the Internet Works
 Data is passed in chunks called
 The Internet transmits data
packets
from one computer (called a
 Transmission Control Protocol
host) to another
(TCP): widely used transport-layer
 If the receiving computer is on
protocol that is used in
combination with IP by most
a network to which the first
Internet applications
computer is directly connected,
 Uniform Resource Locator (URL):
it can send the message
an assigned address on the
directly
Internet for each computer
 If the receiving computer is
not on a network to which the
sending computer is connected,
the sending computer relays
the message to another
computer that can forward it
How the Internet Works
 Accessing the Internet
 Connect via LAN server
 Connect via Serial Line
Internet Protocol
(SLIP)/Point-to-Point
Protocol (PPP)
 Connect via an online
service
 Several other ways to
connect
 Example: WAP
Internet Service Providers
 Internet service provider (ISP): any company that provides
individuals or organizations with access to the Internet
 Most charge a monthly fee
 Many ISPs and online services offer broadband Internet access
through digital subscriber lines (DSLs), cable, or satellite
transmission
The World Wide Web
 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
want
 Hypertext Markup Language
(HTML): the standard page
description language for Web
pages
 HTML tags: codes that let the
Web browser know how to format
text - as a heading, as a list, or as
body text - and whether images,
sound, and other elements should
be inserted
Web Browsers
 Web browser: software that creates a unique,
hypermedia-based menu on a computer screen, providing
a graphical interface to the Web
 The menu consists of graphics, titles, and text with
hypertext links
 Popular Web browsers: Microsoft Internet Explorer,
Netscape Navigator, Mozilla Firefox, Apple Computer’s
Safari
Search Engines and Web Research
 Search engine: Web search
tool
 Examples: Yahoo.com,
Google.com
 Most search engines are free
 Searches can use words, such
as AND and OR to refine the
search
 Meta-search engine: submits
keywords to several individual
search engines and returns
results from all these search
engines
Internet Cell Phones and Handheld
Computers
 Some cell phones can be connected to the Internet
to:
 Search for information
 Buy products
 Chat with business associates and friends
 Handheld computers and other devices can be
connected to the Internet using phone lines or
wireless connections, such as Wi-Fi
Intranets and Extranets
 Intranet
 Internal corporate network
built using Internet and World
Wide Web standards and
products
 Used by employees to gain
access to corporate
information
 Reduces need for paper
 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): secure connection
between two points across the
Internet
 Tunneling: process by which
VPNs transfer information by
encapsulating traffic in IP
packets over the Internet
Net Issues
 Management issues
 No centralized governing body controls the Internet
 Service and speed issues
 Web server computers can be overwhelmed by the amount of
“hits” (requests for pages)
 Privacy, fraud, security, and unauthorized Internet
sites