Chapter 9 Basic Information Systems Concepts Sumber dari

Chapter 9: Basic Information Systems Concepts Sumber dari : http: //www. prenhall. com/divisions/bp/app/mart in 3/ppt/Chap 9. ppt.

Definitions u. A system is a set of interrelated components that must work together to achieve some common purpose. u A subsystem is a component of a system which is also viewed as a system.

Definitions u An information system is a collection of computer hardware and software, procedures, documentation, forms, and people responsible for the capture, movement, management, and distribution of data and information.

System Boundary u Dividing line u Placed based on the purpose -- usually not a fixed line u Control or redesign within the boundary u Environment outside the boundary

System Interface u Where a system meets its environment or where one subsystem interacts with another subsystem u Code/decode and filter u Error detection and correction u Hold/buffer u Security and validate/reject u Provides decoupling of components

Hierarchical Decomposition u Factor systems into subsystems u Examine interfaces u Keep going deeper until subsubsystems are understandable u Uses -- analysis and design u Purposes -- cope with complexity, communication, identification of interfaces, seek decoupling

Definition of Business Process Reengineering u Hammer & Champy’s quick definition: “starting over. ” u Hammer & Champy’s full definition: “Reengineering is the fundamental rethinking and radical redesign of business processes to achieve dramatic improvements in critical, contemporary measures of performance. ”

Business Process Reengineering u Information technology is the essential enabler which permits companies to reengineer business processes. u Businesses must take advantage of the disruptive power of technology. u In the U. S. , there have been great savings, but also tremendous costs in terms of jobs and people.

Revised Definition of BPR u Business process reengineering is the radical redesign of business processes to achieve dramatic improvements in their performance by taking advantage of information technology. u radical -- dramatic -- processes -information technology

Commonalities in Successful BPR Efforts u Several jobs are combined into one. u Workers make decisions. u The steps in the process are performed in a natural order. u Work is performed where it makes the most sense.

Commonalities in Successful BPR Efforts (continued) u Checks and controls are reduced, and reconciliation is minimized. u Hybrid centralized/decentralized operations are prevalent.

Using Information Technology to Break Dysfunctional Rules Example #1 u Old rule: Information can appear in only one place at one time. u Disruptive technology: Shared databases u New rule: Information can be used simultaneously in many places.

Using Information Technology to Break Dysfunctional Rules Example #2 u Old rule: Only EXPERTS do complex work. u Disruptive technology: Expert systems u New rule: Generalists can do complex work like an EXPERT.

Using Information Technology to Break Dysfunctional Rules Example #3 u Old rule: Field personnel need OFFICES to receive, store, retrieve, and transmit information. u Disruptive technology: Portable and home computers, modems, and wireless data communication u New rule: Field personnel send and receive info. WHEREVER they are.

The Information Systems Life Cycle u. Definition phase u. Construction phase u. Implementation phase

IS Development: Procedural. Oriented Techniques u Documenting the existing system: the As-Is model u Creating a model of the desired future system: the Logical To-Be model u Interpreting the logical model as a physical system design: the Physical To-Be model

Tools for the As-Is Model u Describe what you have NOW! u Context diagram (see example) u Work process flow diagram (see example)

Tools for the Logical To-Be Model u Define WHAT you want the new system to do! (Not how it will be done) u Data flow diagram (see example) u Data dictionary u Entity-relationship diagram (see example)

Tools for the Physical To-Be System u Describe HOW the new system will operate! u Program structure chart (see example) u Input form layout u Report layout

IS Development: Object. Oriented Techniques u Key idea: Work with reusable objects to speed up development! u TWO PRINCIPLES: u Storing data and related operations together within objects (encapsulation) u Sharing commonalities between classes of objects (inheritance)

Why Controls? u Assess the quality of performance of the IS function u Control criminal activity u Prevent destruction of data or equipment u Reduce errors

Controls in Information Systems u Backup and recovery u Methodology standards u Edit rules u Security u EDP auditing u System testing u Control calculations

Examples of Controls u Authorization of system development by top management u Corporate data access policy u Separation of duties u Physical controls for data center u Scrutiny of computer logs u “Firewalls”