© 2005 Prentice Hall1-1 Stumpf and Teague Object-Oriented Systems Analysis and Design with UML.

© 2005 Prentice Hall1-2 Stumpf and Teague Object-Oriented Systems Analysis and Design with UML.

© 2005 Prentice Hall1-3 Learning Objectives Explain how systems thinking helps address the complexity of developing an information processing system. Define a system and identify the function, components, and structure of familiar systems. Understand the relationship between a system and its environment or context. Explain the role of an interface. Give examples of information system components which perform the functions of transformation, transmission, and storage.

© 2005 Prentice Hall1-4 Learning Objectives (continued) Explain the difference between essential and implementation descriptions of a system. Describe some of the major roles of information in a business organization. Explain the major steps in a problem- solving or decision-making process and how systems analysis can be understood as problem solving.

© 2005 Prentice Hall1-5 Overview Systems analysis is a discipline which analyzes problems, estimates the consequences of various courses of action, and recommends what action to take to solve problems. Information systems analysis seeks to improve information systems so that they provide better support for the business activities of an organization.

© 2005 Prentice Hall1-6 Overview (continued) Humans cope with complexity by thinking in terms of systems. A system organizes its components into a structure and is separated from its environment by a system boundary.

© 2005 Prentice Hall1-7 Overview (continued) System analysts work with abstract models in order to: Understand existing systems Simulate system behavior Describe the requirements for a new system

© 2005 Prentice Hall1-8 Overview (continued) In general, information systems perform three functions: Transmission of information Storage of information Transformation of information

© 2005 Prentice Hall1-9 Overview (continued) The important overall function of an information processing system is to respond to what happens in the outside world by transforming inputs into the desired outputs.

© 2005 Prentice Hall1-10 Overview (continued) System analysts help solve business problems by applying information technology not only to production and service functions but also to improved monitoring, control, and decision support.

© 2005 Prentice Hall1-11 Coping with Complexity In order to structure and simplify complexity, we: Limit the extent of our interest Select only the important or essential features Break up the complexity into manageable small pieces Examine things iteratively Review and refine in order to improve Use visual thinking whenever we can

© 2005 Prentice Hall1-12 What Is a System? A system is an interrelated set of components which are viewed as a whole. It has: Components – its basic parts Structure – how the components are organized Function – what the system does Objectives – the human purposes served by the system

© 2005 Prentice Hall1-13 System Structures Hierarchical (Tree)  Each component is subordinate to exactly one other component.  Components can be nested. Matrix (Grid)  Each component, or cell, is determined by a combination of two or more factors. Network  Nodes or points connected by arcs or links.  Arcs may permit flows, as in a transportation or telecommunication network.

© 2005 Prentice Hall1-14 Hierarchical System Structure.

© 2005 Prentice Hall1-15 Matrix System Structure.

© 2005 Prentice Hall1-16 Network System Structure.

© 2005 Prentice Hall1-17 A System and Its Environment A system has a boundary which separates it from its environment.

© 2005 Prentice Hall1-18 Interfaces An interface describes an interaction or connection between a system and its environment, or between subsystems.

© 2005 Prentice Hall1-19 System Models A system model is an abstract, selective system description used to: Understand the system Study system behavior Communicate our understanding of the system to others

© 2005 Prentice Hall1-20 System Models (continued) A representation of a model is a graphical or physical way of displaying the components and relationships in the model.

© 2005 Prentice Hall1-21 Generating a System Model We generate a system model through: Aggregation: Assembling it out of a set of elementary components, or primitives, through synthesis – a bottom-up process. Decomposition: Partitioning the whole into its constituent parts through analysis – a top-down process.

© 2005 Prentice Hall1-22 Functions of an Information Processing System Communication  Moves or transports information from place to place Storage  Records and saves information for future use Transformation  Changes information content by deriving outputs from inputs using a known, defined procedure

© 2005 Prentice Hall1-23 Automated Information Processing Systems Hardware  Data capture and display devices  Processing units  Memory (volatile and permanent)  Channels for information flow Software  Operating system and related software  Communications software  Application software

© 2005 Prentice Hall1-24 System Descriptions Implementation Descriptions  Dependent on a specific implementation or technology  Sometimes called physical descriptions Essential Descriptions  Independent of a specific implementation or technology  Sometimes called logical descriptions

© 2005 Prentice Hall1-25 System Descriptions (continued) Implementation Description Non-essential Shows form Concrete Implementation- dependent Technology- dependent Essential Description Essential Shows content Abstract Implementation- independent Technology- independent

© 2005 Prentice Hall1-26 A Systems View of Business Industrial or manufacturing businesses, which produce goods Service businesses, which do not produce goods

© 2005 Prentice Hall1-27 A Systems View of Business (continued).

© 2005 Prentice Hall1-28 A Systems View of Business (continued).

© 2005 Prentice Hall1-29 Roles of Information in Business 1.It helps carry out the production and service functions of the organization. 2.It measures and monitors the performance of these primary business functions and other supporting functions. 3.It helps the organization control its operations to meet performance targets. 4.It supports management decisions to improve the business by modifying the organization or changing its objectives.

© 2005 Prentice Hall1-30 The Problem-Solving Process 1.Identify the problem. 2.Generate possible solutions. 3.By applying constraints, eliminate proposals which do not solve the problem. 4.Evaluate the expected performance or behavior of each proposed solution.

© 2005 Prentice Hall1-31 The Problem-Solving Process (continued) 5.Using the criteria, compare the alternatives to select the best solution. 6.Plan how to implement the selected solution. 7.Implement the solution. 8.Evaluate the performance of the solution after its implementation.

© 2005 Prentice Hall1-32 Summary System analysts apply information technology to business problems and systems in order to improve production and services as well as provide improved monitoring, control, and managerial decisions. Basic systems concepts and models help analysts succeed in addressing the complexity of real-world systems.