Basic Structural Modeling - Unit II

Basic Structural Modeling

Classes

• A class is a set of objects sharing attributes, operations, relationships, and semantics.
• Graphical representation of a class is a rectangle.
• Each class has a name, which is either a simple name (just the class name) or a qualified name (class name plus package name).

Attributes

• Attributes represent properties of a class, defining possible values instances can hold.
• A class can have many or few attributes; attributes describe shared characteristics (e.g., height, width for a Wall class).

Operations

• Operations are services that can be invoked on class objects, representing behaviors that affect object state.
• Example operations in a Rectangle class include moving, resizing, or querying its properties.
• Operations are depicted below attributes graphically and include signatures (name, type, default values, return type).

Organizing Attributes and Operations

• Not every attribute and operation needs to be depicted in a class diagram; only relevant ones should be displayed.
• Use ellipses ("...") to indicate more attributes or operations exist than shown.

Responsibilities

• Each class has responsibilities representing its obligations toward maintaining state and behavior.
• Examples: Wall class manages dimensions; FraudAgent class processes and evaluates orders; TemperatureSensor class monitors temperature levels and triggers alarms.

Common Modeling Techniques

Modeling System Vocabulary

• Classes are used to model abstractions relevant to solving a specific problem or therapeutic solution.
• Identify key terms critical to users or implementers through methods like CRC cards and use case analysis.
• Ensure each class has clearly defined roles and responsibilities.
• Example classes could include Customer, Order, Product, Shipment, Invoice, and Transaction.

Distribution of Responsibilities

• As the number of classes increases, it's vital to ensure responsibilities are balanced among them, allowing for manageable and logical structuring of the system's vocabulary.