Transcript Multimedia Communication

Multimedia Communication
Bandwidth & Basic Web Terminology
CP586 © Peter Lo 2003
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Internet History
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The Internet began in1969 as the Advanced Research Projects
Agency Network, better known as ARPANET.
The project was developed by the US Department of Defense and
was later made available to universities and other organizations.
The WWW started in 1989 at CERN, a European laboratory for
particle physics in Geneva.
CERN researchers developed the protocol for the free exchange of
information and ideas related to physics and science.
The system was text based and there was no intention of adding
sound and video, let alone images.
Once HTTP was developed, client server software was written.
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WWW Terminology
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The WWW stands for the World Wide Web.
HTTP stands for Hypertext Transfer Protocol.
URL stands for Universal Resource Locator and
can denote http, ftp and Telnet recourses.
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HTTP
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HTTP is Short for Hyper Text Transfer Protocol, the
underlying protocol used by the World Wide Web.
HTTP defines how messages are formatted and
transmitted, and what actions Web servers and browsers
should take in response to various commands.
HTTP is called a stateless protocol, because each
command is executed independently, without any
knowledge of the commands that came before it.
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Bandwidth
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The amount of data that can be transmitted in a
fixed amount of time.
For digital devices, the bandwidth is usually
expressed in bits per second(bps) or bytes per
second.
For analog devices, the bandwidth is expressed in
cycles per second, or Hertz (Hz).
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Fiber Optic Cable
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Uses glass (or plastic) threads (fibers) to transmit data.
A fiber optic cable consists of a bundle of glass threads, each of
which is capable of transmitting messages modulated onto light
waves.
Fiber optic cables have a much greater bandwidth than metal
cables.
Fiber optic cables are less susceptible than metal cables to
interference (e.g. magnetic).
Fiber optic cables are much thinner and lighter than metal wires.
Data can be transmitted in a digital format.
When you multiplex a signal it allows you To combine multiple
signals (analog or digital) for transmission over a single line or
media.
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HTML Issues
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HTML stands for Hyper Text Markup Language.
HTML lack WYSIWYG capabilities.
Different HTML versions in conjunction with
poor co-operation between the leading browsers
make truly cross platform web pages very difficult
to achieve.
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ISDN
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ISDN stands for integrated services digital
network.
ISDN is designed to carry large amounts of
information at a fast rate of speed.
ISDN is especially suited for the transmission of
high quality audio and video.
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ISO
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Short for International Organization for
Standardization.
Note that ISO is not an acronym; instead, the
name derives from the Greek word iso, which
means equal.
For example, ANSI (American National Standards
Institute) is a member of ISO.
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Communication Terminology
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The Internet uses TCP/IP (Transport Control
Protocol / Internet Protocol).
A packet is the basic unit of communication within
TCP/IP.
Asynchronous data flow is typically made up of a
number of different packets.
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OSI Reference Model
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OSI stands for Open System Interconnection, an
ISO standard for worldwide communications that
defines a networking framework for implementing
protocols in seven layers.
What was once thought to become the universal
communications standard now serves as the
teaching model for all other protocols.
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OSI Reference Model
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Networks
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Local Area Network (LAN)
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Wide Area Network (WAN)
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Connects computers in a single office/building.
Connects networks over a large area.
Metropolitan Area Network (MAN)
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Connects networks around a town or city.
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Local area network (LAN)
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Network in limited
geographical area such
as home, school
computer laboratory, or
office building
nodes in network
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Peer-to-peer LAN
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Small network that
shares hardware, data, or
information located on
any other computer in
network
Each computer stores
files on its own storage
devices
network operating
system and
application software
installed on each
computer
printer may be used by
all computers on
network
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Client/server LAN
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Network in which one or more computers act as a server
and other computers on the network can request services
from server
client
laser printer
client
server
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client
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Wide area network (WAN)
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Network that covers
large geographic area
Internet is world’s
largest WAN
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communications
satellite
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Internet use of peer-to-peer (P2P)
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Enables users with same networking software to connect to
each other’s hard disks and exchange files directly
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Metropolitan area network (MAN)
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Backbone network that connects local area networks in a
metropolitan area such as a city or town
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Types of Networks
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100 Base-T.
100 Base-VG.
Token Ring.
Ethernet.
Integrated Services Digital Network (ISDN)
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Transmission Alternatives.
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Telecommunications Network.
Cable TV.
Terrestrial Broadcast.
Satellite Broadcast.
ISDN.
Fibre Optic Cable.
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Internet Addressing
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Domain Name Server (DNS)
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Top level domains
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Second level domains
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Describe the category of use. (Eg. COM, GOV, EDU, NET,
AU)
Describe specific users or organizations within first level
domains (Eg. Ballarat, IBM, Star Wars)
Third or subsequent levels
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Specify a particular user or computer.
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Reference
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Discovering Computers World 2003 (Ch. 6)
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