Transcript No Slide Title

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
–
–
–
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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;
• The generated content/ data is updated in real time.
• They 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 - applicationwhich 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 Information System.
Critical areas:
1.
2.
3.
4.
•
network design and management
processing architecture
desktop environment
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:
–
–
–
–
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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
•
•
•
•
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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 multivalued 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 (5th Edition). Pearson,
Prentice Hall. Chapter 14.
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