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Object Oriented Business Modelling, Systems Analysis, and Systems Design (IS 2204 )

Object Oriented Business Modelling, Systems Analysis, and Systems Design (IS 2204 ). 15/9/14 Introduction to systems development. Dr. Ciara Heavin Business Information Systems. Lifecycle and methodology: Learning Outcomes. After completing these lectures students should be able to:

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Object Oriented Business Modelling, Systems Analysis, and Systems Design (IS 2204 )

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  1. Object Oriented Business Modelling, Systems Analysis, and Systems Design (IS2204) 15/9/14 Introduction to systems development Dr. Ciara Heavin Business Information Systems

  2. Lifecycle and methodology: Learning Outcomes After completing these lectures students should be able to: • Define the concept of systems development methodology and explain its role • Understand the importance of requirements and their analysis • Discuss the characteristics of various types of systems development methodologies such as data-driven, OO and Agile • Define the concepts of model and diagram and explain their role in the systems development process • Identify various types of models used in IS development 2nd year BIS / IS2204

  3. Recap: Information systems in business and management • Information as a resource • How is it managed? • Technological background • and related change • Users • Influence (internal or environmental) • Form of information: detailed vs. summarized • Functionality 2nd year BIS / IS2204

  4. Recap: Information systems development • Understand business processes • And their environment (they exist in) • Analyse and Model • Feedback • Design system • Develop and construct • Install (put into use) • Maintain • Improve 2nd year BIS / IS2204

  5. (Business/Management) Information Systems • “information” has many definitions • “information systems” have just as many • The integration and relationships of People, processes, data and technology • Hardware – software – data – procedures – people (Kroenke) • Organizations, management and technology (Laudon) 2nd year BIS / IS2204

  6. Why study MIS/BIS • To understand technology and its • development, • management (operations) and • use • Consider and understand its (potential and actual) impact • Be able to assess future trends, evaluate how they might affect businesses, and apply them successfully 2nd year BIS / IS2204

  7. Systems by functional areas • Predictions • (coupled w/ accounting) • Supplier • (coupled w/ manufacturing) • Sales – Customers • (coupled w/ marketing) • Learning • (coupled w/ HR) • Accounting • Manufacturing • Marketing • Human Resource • Integration : ERP 2nd year BIS / IS2204

  8. The lifecycle of a system • Development • SDLC: analysis, design, construction, implementation • Management (operations) and maintenance • Installation • Use • Revisions • Decommissioning 2nd year BIS / IS2204

  9. This module focuses on: the development of systems • Participants • Roles • Management • Analysts • SMEs • … • Process • Methodology • Phases • Work products • Models • Project • Teamwork • Planning • Status • Outcome • Product • Solution • (system) • … and its use • Functionality 2nd year BIS / IS2204

  10. Definition : Analysis & Design • Analysis : what users need the system to do • Expressed through models • Depicted in diagrams • Design : how the system will meet the need 2nd year BIS / IS2204

  11. Analysis = listening Intimidated users => confusion 2nd year BIS / IS2204

  12. Design = making decisions It is difficult to understand users’ expectations 2nd year BIS / IS2204

  13. Understanding requirements ... • Analysing problems • Narrative (what the situation is, what the problem is about) • Activity diagram • Context diagrams (e.g. level 0 DFD) • Use cases (OO) • Functional decomposition • Process specification • Data flow diagrams (level 1 and below) • Entity relationship model • Object model (with domain objects) • Designing solutions • Data schema • Application specifications • Object model with design objects • UI 2nd year BIS / IS2204

  14. System Development Methodology Formal and precise process • Driving principles and a set of related techniques • Activities, methods, practices • E.g. to evaluate the costs and benefits of different solutions • Organized into a series of phases • Set of defined deliverables • A corresponding set of tools • Serving various participants and their needs • Project management tools • Modelling tools • Development management tools 2nd year BIS / IS2204

  15. OO approach • Used for systems where • changes to data structure or processes are more frequent • Neither data nor process “heavy” • There is “green field” development (no legacy issues) • Puts reusability and data protection to the driver’s seat • No “common” (shared) data • Working with the same type of data (re)uses same code • Models can turned into code through clear, step-by-step transformations 2nd year BIS / IS2204

  16. Development mindset THE world (problem) Construction SDLC reality Impl. model system (env.) requirements user requirements language feedback, test, QA its model code Use, maintenance feasibility Design /UI high level documentation Project management low level s/w 2nd year BIS / IS2204

  17. Model • A Model is a simplified representation of a complex reality, usually for the purpose of understanding that reality, and having the features of that reality necessary for the current task or problem • Modelling is a form of abstraction -the process of focusing on those features that are essential for the task at hand and ignoring those that are not • Models are usually captured in the form of a diagram, thus a visual representation of the model 2nd year BIS / IS2204

  18. Logical vs. Physical models • Logical models show what a system is or does. They are implementation independent. • Physical models show not only what a system is or does, but also how the system is physically and technically implemented. 2nd year BIS / IS2204

  19. Building a model • Functional decomposition • Context diagram • Data Flow Diagram • Context level • Processes • Data Flow • Data store • External entities • (system interfaces or human actors) 2nd year BIS / IS2204

  20. Functional Decomposition Diagram • Decomposition is the art of breaking a system into its component subsystems, processes, subprocesses. Each level of abstraction reveals more or less detail about the overall system or a subset of that system • a decomposition diagram shows the top-down functional decomposition and structure of a system 2nd year BIS / IS2204

  21. Context diagram • WHAT IS THE CONTEXT IN WHICH THE SYSTEM IS USED • THIS WILL IDENTIFY THE MAIN INTERNAL & EXTERNAL DIMENSIONS OF THE SYSTEM Global Airline seat booking On-line reservation system Internet Users 2nd year BIS / IS2204

  22. Data Flow Model • Goal, purpose • Process modelling concept • Depicts the flow of data through a system and the work or processing performed by that system • (Also called process model) • Context level • Level 1 • Level 2 • A Data Flow Diagram (DFD) is a graphical tool • Components • Notation 2nd year BIS / IS2204

  23. DFDs Entity • Function • Process • Data • Various notations… • DFC • Gane-Sarson customer transaction Process (Execute transaction) Data store 2nd year BIS / IS2204

  24. DFDs • Function • Process • Data • Various notations… • DFC • Gane-Sarson Entity customer transaction Process (Execute transaction) Data store 2nd year BIS / IS2204

  25. Flowcharts • System Flowcharts are diagrams • that show the flow of control through a system • while specifying all programs, inputs, outputs, • and file/databases accesses and retrievals • as well as steps and decision points in a process 2nd year BIS / IS2204

  26. 2nd year BIS / IS2204

  27. Example : www.ryanair.com 2nd year BIS / IS2204

  28. Functional decomposition 2nd year BIS / IS2204

  29. Context level DFD Customer Provides travel details Global Airline seat booking Provides options Makes booking w/ payment 2nd year BIS / IS2204

  30. Example : www.ryanair.com • Input : • Flight details (eg. SNN-BVA, 8 Oct, 10.35) • Credit card details (eg. VISA no, Expiry date) • Process : • Confirms price (eg. EUR 79) • Makes reservation • processes payment • Output : • Reservation reference (eg.CGHKCA) 2nd year BIS / IS2204

  31. ERDs • Data modelling concept • Entity • With attributes • And their relationship(s) • Cardinality and Degree • Min-max • Number of entities in a relationship • Cardinality and Modality • Max # • 0 or 1 min at the instance level (does 1 have to exist?) 2nd year BIS / IS2204

  32. Entity relationship diagrams • ERD’s are used to illustrate the logical structure of databases Attribute Attribute Attribute Relationship Entity Entity Attribute Attribute 2nd year BIS / IS2204

  33. Sample ERD 2nd year BIS / IS2204

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