Chapter 5

Logical Model

A representation of what a system MUST do, independent of physical implementation.

Physical Model

A description of HOW a system will be constructed, showing implementation of system requirements.

Sequence

A logical structure where steps are completed in a sequential order.

Selection

A logical structure where one or more process steps are completed based on a test or condition.

Iteration

A logical structure where a step is repeated until a specific condition changes.

Entity

A person, place, thing, or event for which data is collected and maintained.

Source

An entity that supplies data to a system.

Sink

An entity that receives data from a system.

Data Flow Diagram (DFD)

A visual representation of data movement within a system.

Process

A business activity that receives input data and produces output with different content or form.

Data Store

Represents data that is stored for future use by one or more processes.

Context Diagram

A top-level view of an information system showing system boundaries and scope.

Diagram 0 DFD

An overview of all components interacting to form the overall system.

Functional Primitive

A process that consists of a single function that cannot be further decomposed.

Structured English

A subset of standard English used to describe logical processes clearly.

Decision Table

A logical structure showing every combination of conditions and outcomes.

Decision Tree

A graphical representation of conditions, actions, and rules from a decision table.

Data Dictionary

A central storehouse of information about a system's data elements, flows, and processes.

Object Oriented Analysis

A method of describing an information system by identifying objects and their interactions.

Object

Represents a real person, place, event, or transaction in a system.

Method

A task or function that an object performs upon receiving a message.

Attribute

A characteristic that describes an object.

Class

A group or category of objects.

Subclass

A more specific category within a class.

Inheritance

An object relationship allowing an object to derive attributes from another object.

Use Case

Represents steps in a specific business function or process.

Use Case Diagram

A visual summary of related use cases within a system.

Class Diagram

Shows object classes and relationships involved in a use case.

Sequence Diagram

A dynamic model showing interactions among classes over time.

State Transition Diagram

Illustrates how objects change from one state to another.

Activity Diagram

A horizontal flow chart showing actions and events as they occur.

Business Process Modeling

A tool to represent people, events, and interactions in a system.

Unified Modeling Language (UML)

A method for documenting and modeling object-oriented systems.

Object Message

A command telling an object to perform a specific method.

Encapsulation

The concept that all data and methods are self-contained within an object.

Polymorphism

A message that gives different meanings to different objects.

In-house Development

Creating software internally to meet unique business requirements.

Software Package

A commercially produced software product purchased or leased from another firm.

Outsourcing

Transferring information system development or maintenance to an outside firm for a fee.

Fixed Fee Model

A pricing model with a set fee based on a specified level of service.

Subscription Model

A variable fee based on the number of users or workstations accessing an application.

Request for Proposal (RFP)

A document describing company needs and required IT services or products.

Request for Quotation (RFQ)

A document requesting price quotations for a specific product or service.

Web 2.0

A second generation of the web enabling collaboration and information sharing.

Horizontal Application

Software that can be used by various types of organizations.

Vertical Application

Software developed for specific business information requirements.

Service Provider

A firm offering outsourcing solutions.

Software as a Service (SaaS)

A model delivering software functionality on demand via the internet.

Software License

A legal agreement granting users the right to use software under specific terms.