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Lecture

lecture_1_-_in.docx

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Department
Information Technology
Course Code
ITEC 1000
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all

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Introduction to Information Technology ITEC 1000 – Winter 2010 – Peter Khaiter Lecture 1 – Information Systems and Technology: Basic Concepts – Jan 4 General Systems Theory - System’s Concept o Definition – a system is a set of components that interact with one another and serve for a common purpose or goal. o Systems may be abstract or physical.  An abstract system is conceptual, a product of a human mind. That is, it cannot be seen or pointed to as an existing entity. Social, theological, cultural systems are abstract systems. None of them can be photographed, drawn or otherwise physically pictured. However, they do exist and can be discussed, studied and analyzed.  A physical system, in contrast, has a material nature. It is based on material basis rather than on ideas or theoretical notions.  Either system has nine main characteristics: • Components • Interrelationships • Boundary • Purpose • Environment • Input • Output • Interface • Constraints - System’s Characteristics o A component is either an irreducible part or an aggregate of parts, also called a subsystem. The simple concept of a component is very powerful. For example, in case of an automobile we can repair or upgrade the system by changing individual components without having to make changes the entire system. o The components are interrelated; that is, the function of one is somehow tied to be function of the others. For example, in the story system the work of one component, such as producing a daily report of customer orders, may not progress successfully until the work of another component is finished, such as sorting customer orders by date of receipt. o A system has a boundary, within which all of its components are contained and which establishes the limits of a system, separating it from other systems. o All of the components work together to achieve some overall purpose: the system’s reason for existing. o A system operates within an environment – everything outside the system’s boundary. The environment surrounds the system, both affecting it and being affected by it. For example, the environment of a university includes prospective students, foundations, funding agencies and the new media. Usually the system interacts with its environment. A university interacts with prospective students by having open houses and recruiting from local high schools. o The point at which the system meets its environment are called interface. o A system must face constraints in its functioning because there are limits to what it can do and how it can achieve its purpose within its environment. Some of these constraints are imposed inside the system (e.g. a limited number of staff available). Others are imposed by the environment (e.g. due to regulations). o A system interacts with the environment by means of inputs and outputs. Input is anything entering the system from the environment; output is anything leaving the system crossing the boundary to the environment. Information, energy and material can be both input and output in relation to the environment. People, for example, take in food, oxygen, and water from the environment as input. An electrical utility takes on input from the environment in the form of raw materials (coal, oil, water power, etc.), requests for electricity from customers. It provides for output to the environment in the form of electricity. - Feedback and control in a system o Feedback – very often output’s data are returned to the input of the system and used to regulate the system’s activity.  It helps to adjust the system to changes so that the system operates in a balanced state, or equilibrium. Large hotels and motels, for instance, ask guests to fill out cards evaluating the services. This feature of a system is used in control. o Control is the process that measures performance and guides it toward a predetermined goal. o Negative feedback is corrective feedback that helps maintain the system within a critical operating range and reduces performance fluctuations around the norm or standard. Negative feedback is transmitted in feedback control loops. A sensor detects the effect of output on the external environment; this information is returned to the system as input, and necessary adjustments are made according to predetermined goal. o In contrast to negative feedback, which is corrective, positive feedback reinforces the operation of a system by causing it to continue its performance and activities without changes. - Methods of a system’s study o There are several important system’s concepts that help to study a system and understand its functioning:  Decomposition  Modularity  Coupling  Cohesion o Decomposition is the process of breaking down a system into its smaller components. These components may themselves be systems (subsystems) and can be broken down into their components as well. o Modularity is a direct result of decomposition. It refers to dividing a system into chunks or modules of a relatively uniform size. Modules can represent a system simply, making it easier to redesign and rebuild. o Coupling means that subsystems are dependent on each other. But they should be as independent as possible. If one subsystem fails and other subsystems are highly dependent on it, the others will either fail themselves or have problems functioning. o Cohesion is the extent to which a subsystem performs a single function. - ‘Systems’ thinking o Being able to identify something as a system. o Being able to identify subsystems. o Identifying system characteristics and functions. o Identifying where the boundaries are (or should be). o Identifying inputs and outputs to systems. o Identifying relationships among subsystems. Information Systems and Technology - Information system, subsystem and supersystem. o Both control and management have an informational nature, that is among all the possible inputs and outputs (information, energy and matter) they use the only one – information. Information is the central core of all resources in feedback loops while regulating the system activities. Any organization as a system could not survive without information. They need to develop a special system for processing and handling the information flows. o Information – a description of a thing or process. o Technology – a set of tools with a common purpose. o Information technology – a set of tools for managing descriptions of things or processes. o Definition – an information system is a collection of interrelated components that collect, process, store and provide as output the information needed to complete a business task. o Alone with the system boundary (i.e. any inputs and outputs) of an IS, we have to consider the automation boundary – it separates the automated part of the IS (where work is done by computers) from the manual part (where work is done by the people). - Concepts of separation o Separating data and processes that handle data.  We can consider every IS as a three-component system: • Data • Data flows • Processing logic  Data are raw facts that describe people, objects and events in organization (e.g. names, age, and customer’s account number). Data is used in an IS to produce information.  Information is data organized in a form that human can interpret.  Data flows are group of data that move and flow through a system. They include a description of the sources and destinations of each data flow.  Processing logic describes the steps that transform the data and events that trigger these steps.  There are two approaches to IS design: • Process-oriented • Data-oriented  The process-oriented approach is based on what the system is supposed to do. The focus is on output and processing logic. Although the data are important, they are secondary to the application. Each application contains its own files and data storage capacity.  The data-oriented approach is a strategy that focuses on the ideal organization of data, independent of where and how data are used within the system. This approach uses data model that describes the kinds of data needed in the system and the business relationships among the data (i.
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