system analysis ch.5 & 6

A logical model shows what the system must do, while a physical model shows how the system will be implemented.

What is the difference between a logical and physical model?

A graphical tool that shows how data moves through a system and how input is transformed into output.

What is a data flow diagram (DFD)?

Process, data flow, data store, and entity.

What are the four basic DFD symbols?

A function or activity that transforms input data into output.

What does a process symbol represent in a DFD?

Spontaneous generation has output without input; black hole has input without output; gray hole has outputs not possible from the inputs.

What are spontaneous generation, black holes, and gray holes in DFDs?

A place where the system stores data for later use.

What does a data store symbol represent?

An external source or destination of data that interacts with the system.

What is an entity in a DFD?

Keep it simple, use unique names, avoid crossing lines, number processes, and make it easy to understand.

What are guidelines for drawing DFDs?

A top-level DFD showing the system as a single process and its interactions with external entities.

What is a context diagram?

A detailed DFD showing the main processes inside the system.

What is a Diagram 0 DFD?

The process of breaking down higher-level DFDs into more detailed lower-level DFDs.

What is leveling in DFDs?

Making sure input and output data flows match between parent and child diagrams.

What is balancing in DFDs?

A central repository that defines and describes all data elements, flows, stores, and processes in the system.

What is a data dictionary?

The smallest piece of data with meaning within the system.

What is a data element?

A meaningful combination of related data elements.

What is a record (data structure)?

Name, alias, type, length, default value, acceptable values, source, security, and description.

What are common attributes documented in a data dictionary?

Structured English, decision tables, and decision trees.

What are process description tools?

A simplified form of English used to describe logic clearly using sequence, selection, and iteration.

What is structured English?

A tabular method showing all possible conditions and outcomes for a process.

What is a decision table?

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

What is a decision tree?

A design approach using logical structures (sequence, selection, iteration) as building blocks for processes.

What is modular design?

A methodology that models a system using interacting objects; integrates with OOP languages like C++, Java, and Python.

What is object-oriented analysis (OOA)?

A person, place, event, or thing relevant to the system, defined by attributes and methods.

What is an object?

A property or characteristic that describes an object.

What is an attribute?

A task or function performed by an object when it receives a message.

What is a method?

A command that tells an object to perform a method.

What is a message?

The ability of the same message to produce different results depending on the receiving object.

What is polymorphism?

The concept that an object’s data and methods are self-contained (a “black box”).

What is encapsulation?

A group of objects that share common attributes and methods.

What is a class?

A general class that contains common attributes or methods shared by subclasses.

What is a superclass?

A specialized version of a class that inherits attributes and methods from its superclass.

What is a subclass?

A relationship where one object (child) derives attributes and methods from another (parent).

What is inheritance?

Associations that enable objects to communicate and interact during system operations.

What are relationships among objects and classes?

A model showing the relationships and interactions among objects and classes.

What is an object relationship diagram?

The Unified Modeling Language—a standardized way to visualize and document system components and relationships.

What is UML?

A representation of a business function or process initiated by an actor.

What is a use case?

An external entity that interacts with the system by initiating a use case.

What is an actor in UML?

A document that names the use case, identifies the actor, and describes the sequence of steps and assumptions.

What is a use case description?

A visual summary showing actors and related use cases within a system boundary.

What is a use case diagram?

A rectangle that defines what is included inside and outside the system.

What is a system boundary in UML?

A UML diagram showing object classes, attributes, methods, and relationships (including cardinality).

What is a class diagram?

The number of instances of one class that relate to instances of another class.

What is cardinality in UML?

A dynamic UML diagram showing interactions among classes over time in a use case.

What is a sequence diagram?

Lines representing the time period when an object can interact in the use case.

What are lifelines in a sequence diagram?

Interactions or communications between objects, shown with labeled arrows.

What are messages in a sequence diagram?

Periods during which an object is active, sending or receiving messages.

What are focuses in a sequence diagram?

A UML diagram showing how an object changes from one state to another based on events.

What is a state transition diagram?

A UML diagram showing the flow of actions and events and the order in which they occur.

What is an activity diagram?

A method for representing people, events, and interactions within a system, compatible with object modeling.

What is business process modeling (BPM)?

It describes systems in terms of reusable, modular, and maintainable objects.

What is the main advantage of object modeling?

An object model that represents the system using O-O concepts.

What is the end product of object-oriented analysis?

They provide frameworks for documenting and maintaining models and ensure consistency across diagrams.

What do CASE tools do?