Information system building blocks ppt

information system development methodologies ppt and information system design ppt
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Dr.DinoHardy,United Arab Emirates,Teacher
Published Date:25-07-2017
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Information System Analysis and Design (ISAD)Chapter-1: The Systems Development Environment – Basic concepts of IS – System analysis and design definition – SAD: Discuss modern approach – Discuss Organizational Roles • System analyst – Information system types – SDLC :The System Development Life Cycle Using CASE tools (Computer Aided Software Engineering)Systems Theory What is a System? Systems and Subsystems Business organization as a Socio- technical system Information Systems (IS) as a systemWhat is a System?  A collection of parts that work together to achieve a goal/task – Examples • Solar system • Digestive systems • Public transport system • Central heating system • Computer system • Information system  A set of objects and relationships among the objects viewed as a whole and designed to achieve a purposeSystem Elements INPUT PROCESS OUTPUT FEEDBACKSystems Can Be Composed of Subsystems System Elemental Subsys A Subsys B Part C SubsysB-1 Subsys A-1 Subsys A-2 SubsysB-2 Elemental Subsys A-3 part B1What is subsystem?  A subsystem is simply a system within a system. – Automobile is a system composed of subsystems: • Engine system • Body system • Frame system – Each of these subsystem is composed of sub-sub systems. • Engine system: carburetor system, generator system, fuel system, and so sonBad Systems  Fail to meet requirements  Poor performance  Poor reliability  Lack of usability  Example difficulties: – Not to schedule – Not to budget – Runaway = 100% over budget or schedule  Some problems are simply “wicked” problemsReasons for Failure  Complexity – Shifting requirements – Bad estimation – Bad management – New technology  Must tackle complexity by, for example: – Structure partitioning of problem – Organized interaction of parts – Ensure you achieve the task  Systems are subject to the need for continuing changeImportant System Concepts Decomposition – The process of breaking down a system into smaller components – Allows the systems analyst to: • Break a system into small, manageable subsystems • Focus on one area at a time • Concentrate on component pertinent to one group of users • Build different components at independent times 1.14Important System Concepts Modularity – Process of dividing a system into modules of a relatively uniform size – Modules simplify system design Coupling – Subsystems that are dependent upon each other are coupled Cohesion – Extent to which a subsystem performs a single function 1.11Computer-based Information Systems (CBIS) vs Manual Systems  CBIS – Information system that rely on computer hardware and software for processing and disseminating information  Manual systems – Use paper + pencil technology CBIS Components  A Computer-based Information System = Hardware + Software + People + Procedures + Information Data and Information – Data are raw facts about the organization and its business transactions. Most data items have little meaning and use by themselves. – Alternative definition: • Data are a collection of items such as words, numbers, images, and sounds that are not organized and have little meaning individually • Data are raw facts about people, objects, and events in an organization – information: Data that is organizedData flow and processing logic Data flow: – Data in motion, moving from one place in a system to another Processing logic: – The steps by which data are transformed or moved and a description of the events that trigger these stepsProcessing logic example Events: H-W = 0 Event-action: If H-W 40 then Pay = 40 Pay-rate + (H-W – 40 ) (1.5 Pay-rate) Else Pay = Pay-rate H-W End if H-W …. Worked HoursDatabases A shared collection of logically related data designed to meet the information needs of multiple users in organization. Database – Files – Records FieldsLevels of data managements databases File File 1 File 2 N Record 1 Record 2 Record N Filed 1 Filed 2 Character BYTE Character BYTE Character BYTE Filed NTraditional vs database approach Traditional approach Payroll Project system Management System Tax Personal Personal Project data data data data Redundant dataTraditional vs database approach Database approach Payroll Project system Management System Tax Personal Project data data data

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