Information Systems Overview

Data and Information

• Data is a basic unit of information, a raw fact.
• Information is processed data with meaning and context.

Information Classification

• Information can be classified as action or no-action.
• Information can be classified as recurring or non-recurring.
• Information can be classified as internal or external.
• Information can be classified as planning, control or knowledge.

Characteristics of Useful Information

• Information must be relevant to the problem at hand.
• Complete information is crucial, even partial information can be detrimental.
• Accurate information prevents erroneous decisions.
• Current information enables informed decisions.
• Economic factors, like cost of obtaining information, must be considered during decision-making.

What is a System?

• A system is a collection of components working together to achieve a common goal.
• A system transforms input into output through organized processes.
• Information systems use data as input, process it, and generate information as output.

Characteristics of a Useful System

• A system is a whole, with interconnected components.
• Components within a system interact to achieve the overall goal.
• Systems are designed to achieve specific goals or objectives..
• Systems have inputs and outputs as part of their processes.
• System must be controlled for effective operation and achieving goals.
• Systems are often organized hierarchically.
• Systems exhibit differentiation, with specialized components performing distinct functions.

Components of an Information System

• Hardware: Physical components like computers, servers, peripherals
• Software: Programs and instructions that tell the hardware what to do
• Data: Raw facts and figures that are processed into information
• People: Users, managers, and IT professionals who interact with the system
• Processes: Procedures and rules that govern how the system operates
• Networks: Communication channels that connect the different components

Types of Information Systems

• Operational systems support day-to-day activities like sales, payroll, and inventory tracking.
• Management systems help middle managers monitor and control operations.
• Strategic systems assist senior management in making long-term decisions.

Transaction Processing Systems (TPS)

• Basic systems for routine operations at the operational level.
• Record and process transactions related to business activities.

Management Information Systems (MIS)

• Serve middle management by providing reports on performance based on data from TPS.
• Provide answers to routine questions using predefined procedures.

Decision Support Systems (DSS)

• Aid middle managers in decision-making.
• Use internal and external information, including data from TPS and MIS.
• Employ interactive processing and provide decision analysis outputs.

Executive Support Systems (ESS)

• Support senior management by addressing strategic issues.
• Use external information like market trends.
• Combine summarized information from MIS and DSS.
• Feature interactive processing and provide projections.

Phases of System Development Life Cycle (SDLC)

• Planning: Establishes project goals, resources, and timelines.
• Requirements Definition: Determines the desired features and functions of the system.
• Design and Prototyping: Creates blueprints and initial models for the system.
• Software Development: Actual coding and implementation of the system.
• Testing: Validates the functionality and performance of the system.
• Deployment: Makes the system available to users.
• Operations and Maintenance: Provides ongoing support and updates for the system.

Software Modeling

• Activity Diagrams: Represent the flow of activities and actions within a system.
• Initial State: Represents the starting point of an activity.
• Final State: Represents the completion or end of an activity.
• Activity Box: Depicts a specific step or action in the activity flow.
• Decision Box: Represents a decision point with alternative paths.

Use-Case Diagrams

• Represent the functionalities of a system and how users interact with it.
• Use Case: A distinct functionality of a system, component, package, or class.
• Actor: An entity that initiates interaction with the system.

Sequence Diagrams

• Visualize the sequence of interactions between objects or parts of a system.
• Lifeline: Represents an object participating in the interaction.
• Activation Bars: Indicate the period when an object is active or instantiated.
• Message Arrows: Represent communication between objects in the sequence.
• Comment: Provides additional information or clarification about the sequence.