1 IMS9043 IT in Organisations Week 3 IT Architecture and Infrastructure

2 Lecture objectives Understand the strategic arrangement of IS/IT in modern organisations

3 Information Systems & People

4 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

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

6 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.

7 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.

8 Mainframe (server-based) Earliest computerised information systems: Information problem brought to the computer Number crunching Technicians in control Specific tasks

9 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.

10 Personal computer (client-based) The purpose of client/server architecture is to maximize the use of computer resources.

11 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.

12 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

13 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

14 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.

15 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).

16 www vs. internet WWW: application which handles digital standards for storing and retrieving data. GUI-based. Internet: transport mechanism, protocols.

17 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.

18 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.

19 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

20 · IT Infrastructure IT Infrastructure supports the flow and processing of information and includes: Hardware Communication network Middleware Application software Database management software Data

21 Hardware Location –Reach Workstations –Range

22 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

23 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)

24 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

25 Application Software Can reside on one computer or over several Receives requests from the interface layer as messages Communicates with middleware

26 Database management software Choices: Relational database Object-Relational database Object database Single database server Distributed database

27 Choosing which technology Commitment to installed DBMS Legacy systems Extent of OO development in the organisation Availability of relevant expertise Future Plans (IT strategy)

28 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

29 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

30 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)

31 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

32 References Turban McLean & Wetherbe Martin, Brown, DeHayes, Hoffer & Perkins (2005). Managing Information Technology (5 th Edition). Pearson, Prentice Hall. Chapter 14.