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Computer System Components_2 (Standards (examples (Display stds: …
Computer System Components_2
Communication
Hardware
Communication Channels
Physical connections
between computer systems
eg, wire cable, phone lines,
fiber optic cable, infrared light,
radio waves
Interface hardware
Handles communication btwn
computer & communication
channel
eg, modem or
network interface card (NIC)
(now part of comp.)
Software
Control flow of data
Directs data to the proper
applications for use
establish connections
Standards
created by committee OR
become a de facto std through
popular use
examples
Display stds:
Postscript, MPEG-2, JPEG, PNG
Character set stds:
ASCII, Unicode, EBCDIC
Computer languages:
Java, SQL, C, Jaxascript
Multimedia stds:
MPEG-2, MPEG-4, MP3, DVD-ROM
created to ensure
universal compatibility
of data formats & protocols
Protocols
Common ground rules of
communication btwn computers,
I/O devices & many software programs
examples
TCP/IP: btwn computers on
the internet & LANs
SATA: btwn storage devices
& computers
HTTP: btwn web servers &
web browsers
XML, RSS, SIP: new protocols
developed to meet new demands
IT System Architectures
Distributed Processing
Systems
Web-Based
Computing
Peer-to-Peer
Computing
Client-Server Computing
examples
email-, file-, print-,
directory-, web-,
database-, application-,
& remote access services
Adv:
Centralisation
of services
permits
easier admin of
services by IT
easier availability &
location by users
Consistency of resources,
ie files & data, can be
managed & assured
more efficient &
cost-effective hardware
procurement through
purchasing a small
no of very powerful
computers
Multi-tier Architectures
Three-tier architecture
3 computers are
involved in a service
example
client computer,
web server,
database server
N-tier architecture
Two-tier architecture
2 computers are
involved in a service
example
Web browser &
Web server model
used in intranets &
on the internet
A program on a client computer
requests services from a program
on a server computer
Cloud Computing
Platform as a service (PaaS):
tools for a developer to create
& run applications on a
cloud platform
Infrastructure as a service (IaaS):
cloud-based hardware emulation of
virtual machines & networking
Software as a service (SaaS):
applications run on a
server or processing
may be divided on
server & client
Advantages
supports collaboration
scalable to a
variety of host platforms
client's datacentre needs
are simplified;
reduced costs
Reduced maintenance
downtime
lower investment for
short-term projects
Off-site
storage facilities
for an organisation
Risks
Outages or loss of
connectivity may prevent
users from working
Requires long-term
commitment & viability
of cloud services
Quality of
security
is critical
Changes in operating
procedures can result
in data loss