OMG-OCUP2-FOUND100 Exam Dumps : OMG Certified UML Professional 2 (OCUP 2) - Foundation Level

Activity precondition and postcondition constraints are essential for specifying conditions that apply to an activity. Let’s break down the concepts:

• Precondition:
• Postcondition:
• Application Scope:
• Constraining Actions vs. Flow of Objects:

In summary, preconditions and postconditions are essential for ensuring the correctness and validity of an activity, but they are context-specific and apply to specific invocations12.

References:

• Sparx Systems. “Use Case Diagram - UML 2 Tutorial.” 2
• Stack Overflow. “What is the difference between precondition, postcondition, and invariant constraints?” 1
• Stack Overflow. “UML Use-case diagram postcondition implementation (with diagram).” 3

In UML 2, a class diagram is used to depict the structure of a system by showing the system's classes, their attributes, operations (or methods), and the relationships among the classes. The constraint{age >= 18}in thePersonclass diagram indicates a condition that must hold true for the instances of thePersonclass whenever they are used in the context of aBankAccount. This constraint is an invariant of thePersonclass that specifies the rule for the attributeage.

Now, let's consider the provided options and explain why option B is correct:

A. The preferred age to open a bank account is 18 years old or older – This statement is incorrect because the diagram does not indicate a preference; it indicates a constraint or a rule.

B. Only customers who are 18 years old or older can open a bank account – This is the correct statement. The{age >= 18}constraint next to theageattribute of thePersonclass signifies that any instance ofPersonassociated with aBankAccountmust be at least 18 years old. SincePersonis connected toBankAccountwith the role namecustomer, this implies that only persons who are at least 18 can be customers of a bank account.

C. The age condition should only hold when the setAge(Integer) function is called – This statement is incorrect because the constraint{age >= 18}is not a condition that applies only when thesetAgeoperation is invoked. Instead, it is a class invariant that must always hold true for any instance ofPerson.

D. An object of Customer with age set to 18 or greater will raise an exception – This is incorrect because the UML diagram specifies a constraint, not an exception condition. The constraint ensures validity, not the raising of an exception.

The answer is verified according to the UML 2 Foundation documents, such as the UML 2.5 specification, where class diagrams and constraints are defined. The specification states that constraints are semantic conditions or restrictions expressed in natural language text or in a machine-readable language that must hold true for the system being modeled (UML 2.5 specification, section 7.9).

In UML 2, a structured class can have internal parts, which are depicted using 'parts' or 'roles' within the class diagram. These internal parts are used to show the composition of the class in terms of contained classes or components. In the context of the question, the structured class named 'System' contains two parts named 'Subsystem1' and 'Subsystem2'.

Option C is the equivalent definition of 'System' in terms of UML 2 notation for several reasons:

• It represents the structured class 'System' with internal parts correctly labeled as 's1:Subsystem1' and 's2:Subsystem2-[ ]', which indicates the role names 's1' and 's2' followed by the class type 'Subsystem1' and 'Subsystem2' respectively. The notation '1..*' after 's2:Subsystem2-[ ]' suggests a multiplicity, meaning that there can be one or many instances of 'Subsystem2' associated with 'System'.
• The compartmentalization within the structured class is indicative of the composition of the 'System', showing that 'Subsystem1' and 'Subsystem2' are integral parts of the 'System'.
• The notation conforms to the standard UML 2 representation for composite structures, as described in the UML 2 Superstructure Specification, where a class can be broken down into its constituent parts within the class rectangle.

This information is verified against the UML 2 Superstructure Specification, which is the authoritative source for UML notation and semantics. Particularly, this aligns with section 9.3.5 on Composite Structures Diagrams, which details the graphical notation for parts and roles within a structured class.