IT Architecture and

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Nov 7, 2013 (3 years and 9 months ago)

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IMS9043 IT in Organisations

Week 3

IT Architecture and

Infrastructure

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Lecture objectives

Understand the strategic
arrangement of IS/IT in
modern organisations

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Information Systems & People

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Information Infrastructure


There are five major components of the
infrastructure:


Computer hardware


Development software


Networks and communication facilities
(including the Internet and intranets)


Databases


Information management personnel

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Information Architecture


Information architecture
is a high
-
level map
or plan of the information requirements in
an organization.

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Information Architecture



In preparing information architecture, the
designer
requires

two
kinds of information
:


The business needs of the organization

that is, its
objectives and problems, and the contribution that
IT can make.


The information systems that already exist in an
organization and how they can be combined among
themselves or with future systems to support the
organization’s information needs.


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Computer hardware environments (1)


Mainframe environment
.
In the
mainframe environment, processing is
done by a mainframe computer.


The users work with passive (or “dumb”)
terminals, which are used to enter or
change data and access information
from the mainframe.

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Mainframe (server
-
based)

Earliest computerised information
systems:


Information problem brought to the
computer


Number crunching


Technicians in control


Specific tasks

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Computer hardware environments (2)



PC environment.

In the PC configuration,
only PCs form the hardware information
architecture.



Networked (distributed) environment.

Distributed processing

divides the processing
work between two or more computers.

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Personal computer (client
-
based)


The purpose of
client/server
architecture is to
maximize the use of
computer resources.


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Client/Server Architecture


A
client/server architecture

divides networked
computing units into two major categories;
clients and servers.


A
client
is a computer such as a PC or a
workstation attached to a network, which is used
to access shared network resources.


A
server
is a machine that is attached to this
same network and provides clients with these
services.



Client/server architecture gives a company as
many access points to data as there are PCs on
the network.


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Client/Server Architecture


PC LAN (local area
network)


PCs, each with
its own storage



Flexible



Device sharing



Scalability


increased
load catered absorbed by
adding workstations


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Processing architectures: Distributed
Systems


Processing divided (not necessarily
evenly) between client and server


Mainframe or PC combinations


One location or several


inter
-
organisational cooperation


access vast amounts of data


team geographically dispersed computers


new software supports info. exchange/
collaboration

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Distributed systems: Electronic Data
Interchange
(EDI)


Electronic data interchange (EDI)

is the
electronic movement of specially
formatted standard business documents,
such as orders, bills, and confirmations
sent between business partners.



The cost of VANS limited EDI to large
business partners.

However, the situation
is changing rapidly with the emergence of
Internet
-
based EDI
.




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Distributed systems: Web
-
based Systems


Web
-
based systems

refer to those applications or services
that are resident on a server that is accessible from anywhere
via the WWW.



The
only
client
-
side software needed to access and execute
Web
-
based applications is a Web browser environment.




Two important features of Web
-
based functionality;


T
he generated content/

data is updated in real time
.


T
hey are universally accessible via the Web to users
(dependent on defined user
-
access rights
).





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www vs. internet


WWW:
application which handles digital
standards for storing and retrieving data.
GUI
-
based.




Internet:

transport mechanism, protocols.


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Distributed systems: Internet and intranet


The
Internet

is a worldwide system of computer
networks
--
a network of networks in which users at
any one computer can, if they have permission, get
information from any other computer.

Transport
mechanism.
(cf. WWW
-

application
which handles digital
standards for storing, retrieving data. GUI based.)


An
intranet

is the use of WWW technologies to
create a private network, usually within one
enterprise.


A security gateway such as a firewall is used to
segregate the intranet from the Internet.


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Internet, intranet as business technologies


Corporate portals:
Web
-
based
personalised gateway to ‘work
-
appropriate’
information and knowledge from disparate IT
systems.


A response to information overload




An
Extranet

(use of the
internet

between
firms) can be viewed as an external
extension of the enterprise intranet.


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IS Infrastructure Areas

The basic facilities, services, and installations needed
for the functioning of an I
nformation System.

Critical areas:

1.
network design and management

2.
processing architecture

3.
desktop environment

4.
operations support strategy



these are critical for a number of reasons; for instance , an
organization would want good performance marks in these
areas before an internet
-
commerce initiative could be
sustained


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IT Infrastructure

IT Infrastructure supports the flow and
processing of information and includes:


Hardware


Communication network


Middleware


Application software


Database management software


Data

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Hardware


Location


Reach


Workstations


Range

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Communication network


Physical communications


Coax, twisted pair, fibre, wireless


Broadband, baseband


Redundancy


Backup


Alternative paths to nodes


Protocols:


ASCII, Ethernet (for LANs), ISDN (Integrated
Services Digital Network), TCP/IP (Transmission
Control/Internet Protocols), Many others


Mixed, proprietary vendor protocols

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Application architectures


An Information System can be looked at
as:


Functionality layer (application domain)


HCI layer (user interface)


Persistent elements layer (dbms)


System architecture layer (middleware)


Foundation layer (building blocks)

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Middleware software

Hardware, software and communication
technologies for data presentation, analysis
and management.


Handles messages from the business logic to
the database


Transparent to the application


WWW middleware


browsers, search engines


Distributed data management


Distributed transaction processing

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Application Software


Can reside on one computer or over
several


Receives requests from the interface
layer as messages


Communicates with middleware

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Database management software

Choices:


Relational database


Object
-
Relational database


Object database


Single database server


Distributed database

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Choosing which technology


Commitment to installed DBMS


Legacy systems


Extent of OO development in the
organisation


Availability of relevant expertise


Future Plans (IT strategy)

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Relational database


Currently the most common form of
implementing databases


Only practical option in heterogeneous
environments


RDBMS expertise is readily available


Object
-
oriented paradigm is compromised

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Object
-
Relational database


Fundamentally a RDBMS


Extended with specially defined data types


Objects in different tables from attribute values


Still compromised by its tabular structure


Some OO features restricted by language
dependence

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Object databases


Not well penetrated into the industry yet


Steep learning curve for existing
developers and relational DBAs


Supports inheritance (language
dependent)


Supports repeating groups and multi
-
valued attributes (not in ORDBMS

because of normalisation constraints)

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Other infrastructure considerations


Security versus Ease of Access


Response time of the network (if the
delay between key press and response
is greater then 3 seconds … frustration)


Breadth of network access

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References


Turban McLean & Wetherbe


Martin, Brown, DeHayes, Hoffer &
Perkins (2005). Managing Information
Technology (5
th

Edition). Pearson,
Prentice Hall. Chapter 14.