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IMS9043 IT in Organisations
Week 3IT 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; • 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. 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 (5th Edition). Pearson, Prentice Hall. Chapter 14.