OMG-OCUP2-FOUND100 Exam Dumps - OMG Certification Questions and Answers

The UML term pair that captures complementary ways of looking at a relationship is "aggregation / composition". Both terms describe types of associations between classes but differ in the degree of ownership and lifecycle dependency between the involved objects. Aggregation implies a weaker relationship where the parent class contains or is linked to other classes but does not strictly control their lifecycle (e.g., a university and its students). Composition, on the other hand, implies a stronger relationship where the parent class has full responsibility for the lifecycle of the associated classes (e.g., a house and its rooms). Understanding these relationships helps model systems more accurately in terms of object ownership and lifecycle management.

The correct answer is Option C based on the UML 2 Foundation concepts for activities and pre/postconditions.

Analysis of the Diagram in Option C:

• The diagram depicts an activity named "Withdraw Money".
• There are two diamonds preceding the activity, representing preconditions. Preconditions are conditions that must be true before the activity can be executed.
• The text within the first diamond indicates that "the amount of money to withdraw is entered".
• The text within the second diamond indicates that "the account has sufficient funds".
• This aligns with the scenario where the user must enter a withdrawal amount and the account must have enough money to cover the withdrawal before the "Withdraw Money" activity can proceed.
• Following the activity, there's a diamond labeled "postcondition," indicating a condition that becomes true after the activity is completed.
• The text within the postcondition diamond states that "the account balance is updated." This reflects the scenario where the account balance is updated after a successful withdrawal.

Comparison with Other Options:

• Option A, B, and D do not explicitly show preconditions and postconditions using the diamond notation, making them less suited to represent the scenario where certain conditions need to be met before and after the action.

References

• UML 2.5.1 Specification (Superstructure): Sections on Activity Diagrams and Pre/Postconditions https://www.omg.org/spec/UML/2.4/Superstructure/PDF

In the UML diagram given, we see two classes,ClassAandClassB, withClassBinheriting fromClassA.ClassAhas two attributes,positionof typeIntegeranddescriptionof typeString.ClassBintroduces an additional attribute,versionof typeReal.

Looking at the instance specifications (the right part of the diagram), we have three instances:a1of typeClassA,b1of typeClassB, andb2also of typeClassB.

In UML, an instance specification must comply with the structure of its classifier, which means an instance ofClassAmust show slots for bothpositionanddescription, whereas an instance ofClassBmust show slots forposition,description, andversion.

In the provided diagram, instancea1ofClassAonly shows a slot forposition. This is an error because it does not show a slot fordescription, which is a defined attribute ofClassA. To correct this error, we would need to add adescriptionslot toa1.

This means that the correct answer is:

B. Add a description slot to a1.

The other options do not correct the error in the model:

A) Specifying unique values forpositiondoes not address the missingdescriptionslot ina1. C) Changing the type ofClassB.versionfromRealtoIntegeris not required by any UML constraint in the context given. D) Changing the type ofClassA.positionfromIntegertoRealdoes not address the missingdescriptionslot ina1and is unrelated to the inheritance structure.

In the provided activity diagram, let’s analyze the execution of Action c:

• Tokens and Control Flow:
• Action c:
• Parallel Flow:

Therefore, the correct statement is that Action c will get executed two times, as indicated by the presence of two tokens offered to it.

For further understanding, you can refer to UML 2 documentation on activity diagrams, which explains the semantics of tokens, control flows, and execution of actions1. Remember that tokens play a crucial role in determining the execution behavior of actions in parallel flows.

In UML, a Class is a template that defines the structure and behavior of objects, whereas a DataType is a type of classifier which specifies a domain of values without identity. Operations (such as money transfers and withdrawals) are behaviors that change the state of an object and, therefore, are defined in Classes rather than DataTypes. This suggests that accounts, which require operations to transfer and withdraw money, should be modeled as Classes.

References:

• UML 2.x Superstructure Specification: Provides definitions for Classes and DataTypes, and details the circumstances under which each should be used. It specifically states that Classes can have operations while DataTypes cannot.
• UML 2.x Infrastructure Specification: This foundational document provides an in-depth explanation of UML modeling constructs, supporting the use of Classes when operations are needed to manage an object's state.

In UML, an initial node is the starting point of an activity thread and represents the start of the flow in an activity diagram. According to the UML 2.5.1 specification, an initial node has no incoming edges and precisely one outgoing edge1. This means that onlyone activity can feed an initial node at the beginning of an activity thread, which aligns with option C.

The initial node is depicted as a filled circle and is used to show where the control starts within the activity. When the activity is invoked, control tokens are placed on the initial node and can then traverse the outgoing edge to the first action or activity node. The specification clearly states that there should be only one outgoing edge, ensuring that the flow of control is unambiguous at the start of the activity.

For further details and verification, you can refer to the UML 2.5.1 specification, particularly Chapter 15.7, which covers the Activity, ActivityFinalNode, InitialNode, and other related elements2. Additionally, the Object Management Group (OMG) provides resources and guidelines for the UML exams, including the types of questions that may appear and the knowledge areas covered3.

It’s important to note that while multiple initial nodes can exist within a single activity diagram, each initial node can only be the source of one outgoing edge, and thus, only one activity can feed each initial node.

An execution occurrence specification in UML sequence diagrams is represented by a thin rectangle on a lifeline. It shows that an instance is performing an action over a period of time.

In the provided sequence diagram, we can see three such thin rectangles on lifeline 'b', which indicates that there are three execution occurrence specifications.

• One for the message that comes from 'a' to 'b'.
• Another one for the message that 'b' sends to 'c'.
• And the last one for the return message from 'c' to 'b'.

There are no execution occurrence specifications on lifelines 'a' and 'c'.

Therefore, the correct answer is:

D. 3