CHAPTER 9 (part a) BASIC INFORMATION SYSTEMS CONCEPTS

THE SYSTEMS VIEW Systems thinking is: a discipline for seeing wholes a framework for seeing interrelationships rather than things an antidote to feeling of helplessness when dealing with complexity Peter Senge (1990) © 2005 Pearson Prentice-Hall Chapter 9 - 2 Page 355

THE SYSTEMS VIEW What Is a System? System – a set of interrelated components that must work together to achieve some common purpose © 2005 Pearson Prentice-Hall Chapter 9 - 3 Page 355

THE SYSTEMS VIEW What Is a System? All components are there … but they don’t work well together! © 2005 Pearson Prentice-Hall Chapter 9 - 4 Figure 9.1 An Example of Poor Design Page 355

THE SYSTEMS VIEW What Is a System? System – a set of interrelated components that must work together to achieve some common purpose Information System – the collection of IT, procedures, and people responsible for the capture, movement, management, and distribution of data and information © 2005 Pearson Prentice-Hall Chapter 9 - 5 Page 355-356

THE SYSTEMS VIEW Seven Key System Elements Boundary Environment Inputs Outputs Components Interfaces Storage © 2005 Pearson Prentice-Hall Chapter 9 - 6 Figure 9.2 General Structure of a System Page 356

Page 357 Figure 9.3 System Component Examples © 2005 Pearson Prentice-Hall Chapter 9 - 7 Figure 9.3 System Component Examples Page 357

THE SYSTEMS VIEW System boundary depends on: What can be controlled Seven Key System Elements – System Boundary System boundary depends on: What can be controlled What scope is manageable within a given time period The impact of a boundary change © 2005 Pearson Prentice-Hall Chapter 9 - 8 Page 357

THE SYSTEMS VIEW Seven Key System Elements – Component Decomposition A component of a system is also called a subsystem or module Hierarchical decomposition – the process of breaking down a system into successive levels of subsystems, each showing more detail © 2005 Pearson Prentice-Hall Chapter 9 - 9 Page 357

THE SYSTEMS VIEW Goals of hierarchical decomposition: Seven Key System Elements – Component Decomposition Goals of hierarchical decomposition: To cope with system complexity To analyze or change part of the system To design and build each subsystem at different times To direct the attention of a target audience To allow system components to operate more independently © 2005 Pearson Prentice-Hall Chapter 9 - 10 Page 357

THE SYSTEMS VIEW Functions of an interface: Seven Key System Elements – Interfaces Interface – point of contact between a system and its environment or between two subsystems Functions of an interface: Filtering Coding/decoding Error detection and correction Buffer Security Summarizing © 2005 Pearson Prentice-Hall Chapter 9 - 11 Page 357-358

THE SYSTEMS VIEW Seven Key System Elements – Interfaces Interfaces built between two preexisting systems are called bridges © 2005 Pearson Prentice-Hall Chapter 9 - 12 Page 359

THE SYSTEMS VIEW Possible objective of an interface: Seven Key System Elements – Interfaces Possible objective of an interface: System decoupling – changing two system components so that modifying one does not necessarily require modifying the other © 2005 Pearson Prentice-Hall Chapter 9 - 13 Page 359

Page 358 Figure 9.4 Sales Summary Reporting System © 2005 Pearson Prentice-Hall Chapter 9 - 14 Figure 9.4 Sales Summary Reporting System Page 358

Page 359 Figure 9.4 Sales Summary Reporting Subsystem © 2005 Pearson Prentice-Hall Chapter 9 - 15 Figure 9.4 Sales Summary Reporting Subsystem Page 359

THE SYSTEMS VIEW Organizations as Systems How does a change in one affect the others? © 2005 Pearson Prentice-Hall Chapter 9 - 16 Figure 9.5 Fundamental Components of an Organization Page 359

THE SYSTEMS VIEW Fundamental principles: Systems Analysis and Design Systems analysis and design (SA&D) – a process used in developing new information systems based on a systems approach to problem solving Fundamental principles: Choose an appropriate scope (boundary selection) Logical before physical (what before how) © 2005 Pearson Prentice-Hall Chapter 9 - 17 Page 360

THE SYSTEMS VIEW Recommended problem-solving steps: Systems Analysis and Design Recommended problem-solving steps: Problem (or system) is a set of problems that must be broken down into smaller, more manageable problems Single solution is not always obvious to all – alternatives should be generated and considered Understanding of problem changes, so reassess commitment to solution at various stages © 2005 Pearson Prentice-Hall Chapter 9 - 18 Page 360

BUSINESS PROCESSES Business process – a set of work activities and resources © 2005 Pearson Prentice-Hall Chapter 9 - 19 Page 361

evaluate a business process One way managers can evaluate a business process © 2005 Pearson Prentice-Hall Chapter 9 - 20 Figure 9.6 Evaluating Business Processes (Keen, 1997) Page 361

BUSINESS PROCESSES Business Process Redesign Business process reengineering (BPR) – radical business redesign initiatives that attempt to achieve dramatic improvements in business processes by questioning the assumptions, or business rules, that underlie the organization’s structures and procedures © 2005 Pearson Prentice-Hall Chapter 9 - 21 Page 362

BUSINESS PROCESSES Six principles for redesigning business processes: Business Process Redesign Six principles for redesigning business processes: Organize business processes around outcomes, not tasks Assign those who use the output to perform the process Integrate information processing into the work that produces the information © 2005 Pearson Prentice-Hall Chapter 9 - 22 Page 363

BUSINESS PROCESSES Six principles for redesigning business processes: Business Process Redesign Six principles for redesigning business processes: Create a virtual enterprise by treating geographically distributed resources as though they were centralized Link parallel activities instead of integrating their results Have the people who do the work make all the decisions, and let controls built into the system monitor the process © 2005 Pearson Prentice-Hall Chapter 9 - 23 Page 362

BUSINESS PROCESSES Business Process Redesign Page 363 © 2005 Pearson Prentice-Hall Chapter 9 - 24 Figure 9.7 How IT Enables New Ways to Work Page 363

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle © 2005 Pearson Prentice-Hall Chapter 9 - 25 Figure 9.8 Generic Systems Life Cycle Page 364

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle Definition Phase: End user and systems analysts conduct analysis of current system and business processes Analysis is: Process-oriented Data-oriented Business case generated and solution chosen © 2005 Pearson Prentice-Hall Chapter 9 - 26 Page 364

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle Construction Phase: System designed, built, and tested System logically described, then physically Technology chosen Programs, inputs, and outputs designed Software programmed and tested User acceptance testing conducted © 2005 Pearson Prentice-Hall Chapter 9 - 27 Page 364

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS The Information Systems Life Cycle Implementation Phase: Business managers and IS professionals install new system Data and procedures from old system converted © 2005 Pearson Prentice-Hall Chapter 9 - 28 Page 364

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Structured Techniques for Life Cycle Development System development methodology – framework consisting of guidelines, tools, and techniques for managing skills to address the business issue Consists of processes, tools, techniques for developing systems Prescribe who participates, roles, development stages and decision points, and formats for documentation © 2005 Pearson Prentice-Hall Chapter 9 - 29 Page 365

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Structured Techniques for Life Cycle Development Structured techniques – tools to document system needs, requirements, functional features, dependencies, and design decisions Procedural-oriented Most common Include data-oriented, sequential, process-oriented activities Object-oriented Newer approach Often used for GUIs and multimedia applications © 2005 Pearson Prentice-Hall Chapter 9 - 30 Page 365

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Procedural-Oriented Techniques Provides a baseline for the new system Includes both logical and physical models © 2005 Pearson Prentice-Hall Chapter 9 - 31 Figure 9.9 Three-Step Modeling Approach Page 365

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Procedural-Oriented Techniques Critical appraisal of existing work processes to: Identify major subprocesses, entities, and interactions Separate processing from data flow Capture relationships between data elements Determine entities and processes within scope © 2005 Pearson Prentice-Hall Chapter 9 - 32 Figure 9.9 Three-Step Modeling Approach Page 365

PROCESSES AND TECHNIQUES TO DELIVER INFORMATION SYSTEMS Procedural-Oriented Techniques Conducted by IS specialists Maps logical requirements to available technology © 2005 Pearson Prentice-Hall Chapter 9 - 33 Figure 9.9 Three-Step Modeling Approach Page 365