Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 1 Managing Information Technology 6 th Edition CHAPTER 9 BASIC INFORMATION SYSTEMS.

Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 1

Managing Information Technology6th Edition

CHAPTER 9

BASIC INFORMATION SYSTEMS CONCEPTS


The Systems ViewWhat is a system?

•A set of interrelated components that must work together to achieve some common purposeSystem

• The collection of IT, procedures, and people responsible for the capture, movement, management, and distribution of data and information

Information System


THE SYSTEMS VIEW

1. Boundary2. Environment3. Inputs4. Outputs5. Components6. Interfaces7. Storage

Seven key system elements


THE SYSTEMS VIEWSeven key system elements

1. Boundary

• Delineation of which elements are within the system and which are outside

2. Environment

• Everything outside the system



2. Inputs

• Resources from the environment that are consumed and manipulated within the system

3. Outputs

• Resources or products provided to the environment by the activities within the system

4.



5. Components

• Activities or processes within the system that transform inputs into intermediate forms or that generate system outputs

• Components can be viewed as subsystems



6. Interfaces

• The place where two components or the system and its environment meet or interact

7. Storage

• Holding areas used for the temporary and permanent storage of information, energy, materials, and so on


THE SYSTEMS VIEWExamples of System Components from Payroll

•Time cards, vouchersInputs•Paychecks, W-2 FormsOutputs•Calculate total pay, subtract deductionsComponents•Match time cards to employees, sort paychecks by departmentInterfaces•Employee benefits, Pay ratesStorage


THE SYSTEMS VIEW

• Some system components can be viewed as systems with their own sets of interrelated components and are called subsystems

• Hierarchical decomposition is the process of breaking a system down into successive levels of subsystems

• Five important goals of hierarchical decomposition:1. Cope with system complexity2. Analyze or change only part of the system3. Design and build each subsystem at different times4. Direct the attention of a target audience5. Allow components to operate more independently

Component Decomposition


THE SYSTEMS VIEW

• One useful framework for examining how information systems fit into organizational systems is based on the Leavitt diamond

• Four fundamental components in an organization are linked– People– Organizational structure– Information Technology– Business Processes

Organizations as systems


THE SYSTEMS VIEW

• Leavitt Diamond– If one is component is changed, the others will

likely be affected as well– For example, new software may have the

following effects:• People have to be retrained• Business processes need to be redesigned• Organizational structures must be modified

Organizations as systems


THE SYSTEMS VIEW

• IT leaders understand that changes in information systems affect the entire organizational system

• One process used in developing new systems that takes into account the systems view is Systems Analysis and Design (SA&D)

• Two key principles:– Choose an appropriate scope– Logical before physical

Systems analysis and design


THE SYSTEMS VIEW

• SA&D has five key design principles• Two key principles stem from key systems

characteristics:1. Choose an appropriate scope

• Selecting the boundary for the IS greatly influences complexity and success of the project

2. Logical before physical• You must know what an IS is to do before you can

specify how a system is to operate

Systems Analysis and Design


THE SYSTEMS VIEW

• SA&D has five key design principles• The other three principles are problem-solving steps:

3. A problem is actually a set of problems and an appropriate strategy is to keep breaking down a problem into smaller, more manageable problems

4. A single solution is not usually obvious to all stakeholders, so alternative solutions representing all parties should be generated before a final solution is selected

5. The problem and your understanding of it could change; thus a staged approach that incorporates reassessments and incremental commitment to a solution is best

Systems Analysis and Design


Business Processes

• In the 1990s many organizations changed from a more functional approach to a more process-oriented approach to better compete globally

• Experts urged companies to radically change the way they did business by starting with a “clean slate” and utilizing IT

“Don’t automate;

obliterate!”- Michael Hammer


• These changes became known as business process reengineering

Business Processes

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


Business ProcessesHow IT Enables New Ways to Work


Business Processes

Six Key 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•Create a virtual enterprise by treating geographically distributed resources as though they were centralized•Lick parallel activities instead of integrating their results•Have people who do the work make all the decisions, and let controls built into the system monitor the process


Processes and Techniques

• Three phases of information system development:1. Definition: end users and systems analysts conduct a

multistep analysis of the current business operations and the information system or systems in the area of concern

2. Construction: designing, building, and testing of a system that satisfies the requirements developed in the Definition phase

3. Implementation: install the new system, which often involves converting data and procedures from an old system

Systems development life cycle (SDLC)


• Procedural-oriented– Most common– Include data-oriented, sequential, process-oriented activities

• Object-oriented– Newer approach– Often used for GUIs and multimedia applications

Structured Techniques


• Tools to document system needs, requirements, functional features, dependencies, and design decisions


• Procedural oriented techniques describe what you have, define what you want, and describe how you will make it so

• Different techniques are used to create the following three models:

1. As-Is2. Logical To-Be3. Physical To-Be



1. As-Is Model• Must identify existing processes, external participants,

other databases or applications, and inputs and outputs

2. Logical To-Be• High-level model of a nonexistent new system• Identifies processes and data• Does not identify who does activity, where accomplished,

or type of hardware or software• Describes “what” rather than “how”

3. Physical To-Be• Requires technology expertise to map the logical

requirements to available technology




• Context Diagram– Positions the system as a whole with regard to

other entities and activities with which it interacts

Techniques for the As-Is Model



• Data Flow Diagram (DFD)– Shows the flows of information through the

system– These consist of four symbols representing:

• External Entity• Data Flow• Process• Data Store

Techniques for the Logical To-Be Model


PROCESSES AND TECHNIQUES



• Data Dictionary/Directory– Used to define data elements




• Entity-Relationship Diagram (E-R Diagram or ERD)

– Used to define relationships among entities




• Draft Layouts– Represents user interface design

Techniques for the Physical To-Be Model


– Primary advantage is object reuse– Can enable quick prototyping

Structured TechniquesObject-Oriented (O-O) Techniques


– Encapsulation– An object contains data and related operations– Allows loosely coupled modules and reuse

– Inheritance– One class of objects can inherit characteristics from others

– Polymorphism– The ability to treat child objects the same as parent objects

(i.e. call methods exactly the same)

Structured TechniquesCore Object-Oriented Concepts


– A set of standardized techniques and notations for O-O analysis and design

• There are several types of UML diagrams used to design systems including

– Use-case diagram– Class diagram

Structured TechniquesUnified Modeling Language (UML)


UML

• Use Case Diagram– Represents the interaction of users with the

system

Unified Modeling Language (UML)


UML

• Class Diagram– Represents each object’s attributes, methods, and

relationships with other objects

Unified Modeling Language (UML)


Information Systems Controls

• All businesses face security risks and only a small percentage of those risks involve IT

• IT can be used to mitigate some business risk through the addition of controls

• There are three types of control mechanisms1. Management policies2. Operating procedures3. Auditing function


Information Systems Controls

• Controls can be built into the information system itself throughout the SDLC


Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 1 Managing Information Technology 6 th Edition CHAPTER 9 BASIC INFORMATION SYSTEMS.

Documents

system outputs components

system complexity

pearson education

prentice hall

key system elements

key system elements

organizational systems

environment slide