OMG-OCUP2-FOUND100 OMG Certified UML Professional 2 (OCUP 2) - Foundation Level Questions and Answers

A domain model's defining characteristic is that it captures the main domain concepts and their relationships. This model focuses on representing the key elements within the problem domain, outlining how these elements interact with each other without detailing the specific implementations. The domain model is an essential tool in software development for understanding and communicating the fundamental structure of the system from a problem domain perspective, helping teams to design solutions that are well-aligned with actual domain needs. UML is often used to represent domain models due to its capability to visually and clearly model complex relationships and structures.

In UML, a static property is one that belongs to the class itself rather than any instance of the class. In UML diagrams, static properties are denoted by underlining the property name.

Now, let's review the options:

A. There is no UML notation in the diagram that specifies whether the property db is a primary key. Primary keys are a database concept and UML does not have a standard way to denote them.

B. The property db is underlined, which indicates that it is a static property. This is the correct UML notation for depicting a class-level attribute.

C. There is no indication in the diagram that db is inherited from a superclass. Inherited properties typically are not underlined (unless they are also static), and there is no superclass shown in the diagram.

D. Underlining in UML does not signify importance or emphasis by the modeler, it indicates that a property is static.

Therefore, the answer isB: The property db is a static property. This is based on standard UML notation as outlined in the UML 2.5 Specification by the Object Management Group (OMG), which dictates that static members (attributes or operations) are underlined in class diagrams.

In UML sequence diagrams, an execution specification is represented by a thin rectangle along a lifeline. It shows where in time the execution takes place, starting with the initiation of an operation or process and ending when that process is complete.

In the interaction diagram provided, we can see an execution specification on the lifelinep1: Pthat starts after the message corresponding to point 3 is received and ends just before the message corresponding to point 5 is sent. This means the execution specification is bracketed by points 3 and 5.

Points 1 and 2 represent message sends, 1 and 4 could represent a message send and receive for the same message, which doesn't typically represent the full execution specification. Points 2 and 3 don't represent a logical start and end of an execution specification because they're on different lifelines.

Therefore, the correct answer is:

D. 3, 5

In UML, Comments are annotations that can be attached to most elements within UML diagrams. Their primary function is not to affect the semantics of the model directly but to provide useful information to anyone reading the model. Comments can help explain or clarify design decisions, make notes about specific parts of the model, or provide any other context necessary for understanding the model better.

The role of Comments in UML is not to enable automatic generation of code comments or to add constraints or semantics to model elements, although they can be associated with model elements to highlight or explain specific attributes or relationships.

References:

• UML 2.x Superstructure Specification: This document describes Comments as a way to provide human-readable descriptions and notes that do not impact the execution or structure of the model but are crucial for documentation and understanding.
• UML 2.x Infrastructure Specification: Further delineates the role of comments in providing clarifications and additional information useful for model interpretation.

To represent an instance of a class in a UML Object Diagram, the standard notation is to specify the instance name followed by a colon and the class name, and then list the attribute values within the compartment.

The class definition forCompanyspecifies that there is one attribute,name, of typeString.

An instance ofCompanywhere thenameattribute has the value "OMG" would be shown as follows:

InstanceName :ClassNameattributeName=attributeValue

In the provided options, Option D correctly represents an instance of theCompanyclass with thenameattribute set to "OMG". The name of the instance is not specified, which is allowed in UML when the instance name is not important or is understood from the context.

Thus, the correct answer is:

D. Option D

In UML sequence diagrams, a signal is typically represented as an asynchronous message without a return value. Asynchronous messages are often denoted with an open arrowhead, and they can represent the sending of a signal.

Looking at the diagram provided, 'p' is sent from 'v2[C]' to 'v3[B]' with an open arrowhead, which indicates that it is an asynchronous message. This fits the common representation of a signal, as it does not expect a response.

'A', 'B', and 'C' do not represent signals in the context of a sequence diagram: A) 'v' is not shown in the diagram; it might refer to a lifeline, which is not a signal. B) 'B' refers to a class or object type and not a message or signal. C) 'm' is represented as a synchronous message (as it has a return arrow), which is not typical for signals.

Therefore, the correct answer is:

D. p

Having all the UML diagrams of a model maintain the same level of detail is typically required by tools that automatically transform the model into other forms, such as code or other types of models. Consistency in the level of detail across different diagrams ensures that automated tools can reliably interpret and convert the UML diagrams without encountering discrepancies that could lead to errors or misrepresentations in the generated outputs. This consistency is crucial for maintaining the integrity of the transformations and for ensuring that the resultant products accurately reflect the intended design and specifications.

In UML class diagrams, relationships between classes are represented in a number of different ways, including generalization, association, and composition.

Looking at the provided options, let's analyze each one:

A. responsiblePerson inherits from Person – This is incorrect because theresponsiblePersonis an attribute of theTaskclass, not a class itself, so it cannot inherit fromPerson.

B. Client and Manager have nothing in common – This is incorrect because bothClientandManagerare specialized types ofPersonas indicated by the generalization arrows pointing toPerson.

C. responsiblePerson can not refer to an object of class Client – This is incorrect.responsiblePersonis typed byPerson, which means that it can refer to an instance of any subclass ofPerson, includingClient.

D. The object referred to as responsiblePerson can be a Manager – This is correct. SinceresponsiblePersonis an attribute of theTaskclass with the typePerson, andManageris a subclass ofPerson,responsiblePersoncan indeed refer to an instance ofManager.

The correct answer is based on the UML 2 Foundation specification that describes how attributes are typed by classes and can refer to instances of these classes or their subclasses (UML 2.5 specification, sections 9.3.3 and 9.5.3). The generalization relationship (represented by a triangle followed by a line) establishes a hierarchy between a more general element and a more specific element, which in this case means thatClientandManagerare both specific types ofPersonand can be used whereverPersonis expected (UML 2.5 specification, section 9.4.5).

The provided image depicts a state machine fragment containing an invalid transition. The state machine has a single state labeled "S1" with an incoming and outgoing transition labeled "e".

According to the UML 2 Foundation documents, a transition in a state machine cannot originate from and target the same state. This type of loopback transition within a single state is not permitted.

Here's a breakdown of why other options are incorrect:

• Option A (A transition requires a trigger or guard) is not necessarily true. Transitions can exist without explicit triggers or guards, although their presence is often recommended for clarity and modeling complex behavior.
• Option B (A guard condition is not allowed on the initial transition) is valid. Guard conditions are indeed not allowed on the initial transition of a state machine, but the issue in the diagram is the loopback, not the presence or absence of a guard.
• Option C (A trigger is not allowed on the transition to the final state) is not always true. Final states can have outgoing transitions with triggers under specific circumstances (e.g., for hierarchical state machines). However, the error here concerns the loopback nature of the transition.

References:

• UML Specification (Superstructure) Version 2.5.1, specifically sections covering state transitions (Section 14.2.3.7). You can find it on the OMG website: https://www.omg.org/spec/UML/2.5.1

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, when you need to reference an element from another package while inside a different package, you use the qualified name. A qualified name includes the package name followed by two colons and then the element name. This ensures that the reference is clear and unambiguous, especially when different packages may have elements with the same name.

The correct syntax for referring to elementOneof PackageP1from inside PackageP2isP1::One, where::is the scope resolution operator used to separate the package name from the element name.

Therefore, the correct answer is:

D. P1::One

In a UML system, the state machine associated with an object becomes active and ready to process events as soon as the object's initialization process is complete. Here's why:

• Object Creation and State Machines: When an object is created, its associated state machine is instantiated along with it. This means the state machine's structural elements (states, transitions, etc.) are established.
• Initialization and the Initial State: During the object's initialization phase, essential attributes and relationships might be set up, and the state machine enters its designated initial state.
• Event Readiness: Once initialization is complete, the object and its state machine are considered "operational" and can respond to events as defined by the state machine's logic.

Why Other Options are Incorrect:

• A. by the time the last state ends: State machines often don't have a designated "last" state. Their execution is based on events and can continue indefinitely. Additionally, a state machine can be ready to handle events long before ending.
• B. immediately after the sequence diagrams start: Sequence diagrams illustrate interactions between objects, but they don't dictate the exact timing of object creation or state machine readiness in the overall system.
• D. when all objects in the system are ready to receive events: While system-wide coordination might be necessary, an individual object's state machine readiness is dependent on its own initialization, not on the state of every other object.

References:

• UML Specification (Superstructure) Version 2.5.1: Specifically, sections covering state machines (https://www.omg.org/spec/UML/2.5.1).
• Practical guides to UML and object-oriented modeling often discuss object creation and state machine lifecycles.

• The execution starts from activity A (as there's no incoming transition).
• From A, there's only one outgoing transition leading to activity E.
• Following the transition from E, the flow reaches activity C.
• There are no further outgoing transitions from C, signifying the end of the valid trace.

Explanation of Why Other Options are Incorrect:

• A. E waits for an Event: The diagram doesn't show an explicit wait event associated with activity E. While an event might trigger the initial start of the activity A, the provided trace (A, E, C) focuses on the control flow between the activities themselves.
• B. E is always executed faster than B: There's no basis to establish a timing relationship between E and B based solely on the structure of the diagram. The order of execution is A, E, C, but their relative speeds cannot be determined from this information.
• D. C waits for tokens on both incoming edges: Activity C has two incoming transitions, but the concept of waiting for tokens on both edges simultaneously doesn't apply here. Since the flow reaches C from activity E, only the transition from E provides the token needed to enable C's execution.

Trace vs. Path

It's important to distinguish between trace and path in an activity diagram:

• Trace: A specific sequence of activity executions along a feasible path.
• Path: A possible route through the activity diagram, which may or may not be a valid trace depending on the presence of decisions or loops.

In this case, the answer focuses on the valid trace A, E, C, which represents a confirmed sequence of activity executions based on the transitions in the diagram.

References

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

In the context of UML Use Case diagrams, the "owner" of a use case is the system or unit that provides the services of the use case. The use case "Book a car" is contained within the "Rental system" boundary, which is represented as a rectangle in the diagram. This indicates that "Book a car" is a function or service provided by the "Rental system."

The "Call-Center Agent" is an actor that interacts with the use case, but it does not own it. The "Car Rental" seems to be a higher-level packaging element (like a system name), but it is not the immediate container of the use case. The "Booking unit" is a part of the "Rental system" that is specifically responsible for the "Book a car" functionality, but in terms of UML semantics, the use case is owned by the system that contains it, which in this case is the "Rental system."

Therefore, the correct answer is:

C. Rental system

In UML, the features of a class are the combined set of attributes (properties) and operations (methods) that are defined for that class. A feature is a characteristic that classifiers (like classes) can possess. In the context of UML, operations are considered behavioral features, while attributes are considered structural features.

Let's analyze the given options in the context of the Car class:

A. "drive()" is an operation (method) of the Car class, but "Car" itself is the name of the class, not a feature.

B. "stop()" is an operation of the Car class, but "driver" is a role name for an association, not a feature of the Car class.

C. "name" is an attribute of the Person class, not the Car class. "stop()" is indeed an operation of the Car class.

D. "drive()" and "stop()" are operations of the Car class. "Person" is not a feature of the Car class, but no attributes of the Car class are shown in the diagram, and since features include both operations and attributes, the correct answer from the available options isD. It is understood that operations of a class are features, so the answer includes both operations of the Car class: "drive()" and "stop()".

According to the UML 2 Foundation specification, both structural features (attributes) and behavioral features (operations) are considered features of a class, so the correct answer would be the operations "drive()" and "stop()" since those are the only features explicitly represented in the Car class in the diagram.

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.

A valuable model in UML and systems design is characterized by its usefulness rather than its complexity or how "correct" it is in an engineering sense. A model's primary objective is to effectively communicate the key aspects of a system or process, and simplicity often enhances this communication by making the model easier to understand and use. The value of a model thus comes from its ability to facilitate decision-making, problem-solving, and understanding among stakeholders. This perspective aligns with the principle of Occam's Razor in modeling, which suggests that simpler solutions are preferable when all other factors are equal. In UML, a model that provides clear insights with minimal complexity is considered more valuable because it is accessible to a wider audience and can be more readily applied to solve real-world problems.

DataTypes in UML are a type of classifier that represents a set of values that do not have identity, which means that two instances of a DataType are indistinguishable if all their attributes are equal. This is in contrast to instances of Classes, which are distinguishable by their identity - each instance is considered unique even if their attributes have the same values.

Option A is incorrect because DataTypes can indeed have operations in UML. Option B is also incorrect; DataTypes can have attributes of any complexity. Option D is incorrect because DataTypes can also have features inherited from their super DataTypes; it is not solely about instantiation.

The UML 2.5 specification discusses DataTypes in section 10.5.8, stating that DataTypes do not have an identity and are often used to type attributes and operation parameters. The equality of DataType instances is based on the equality of their attribute values. Classes, however, are described in section 9.2 of the UML 2.5 specification as elements that can have identity, and instances of a Class are distinguished based on that identity.

The diagram shown is a UML Sequence Diagram, which is used to depict the interaction and order of messages between objects.

In the given diagram, we can see two occurrences of the message 'm' with different parameters (100 and 200), and one occurrence of the message 'p' with the parameter "run".

To determine the minimum number of occurrences that must happen before the reception of 'm(200)', we look at the order of messages:

• The message 'm(100)' must occur.
• The message 'p("run")' must occur after 'm(100)' and before 'm(200)'.

These two occurrences are the minimum necessary before 'm(200)' can be received by the object. The dashed line represents a return message, which does not count as an occurrence for this purpose.

Therefore, the correct answer is:

B. 2

The correct answer is Option B based on its visual representation and alignment with the given scenario:

• Class Start Condition: Both diagrams (Option B and Option C) include a decision diamond labeled "10 Students Present?". This captures the condition for the class to start.
• Professor Arrival: Option B explicitly shows the arrival of the professor using an action rectangle labeled "Professor Arrives". This directly addresses the second part of the scenario where the professor's presence is required.
• Start Activity: Both Option B and C have a subsequent activity labeled "Start Class".

Why Option B is More Accurate:

While both Option B and Option C depict the 10 student condition, Option B goes a step further by including the professor's arrival as a separate action, making it a more precise representation of the two-part requirement for the class to start.

Other Options Analysis:

• Option A: This diagram lacks the "10 Students Present?" condition and the professor's arrival, making it unsuitable for the given scenario.
• Option D: This diagram entirely misses the concept of students or the professor, focusing on a different situation.

References

• UML 2.5.1 Specification (Superstructure): Sections on Activity Diagrams, Decisions, and Actions https://www.omg.org/spec/UML/2.5.1/

• Start Node: Represented by a black circle, indicating the starting point of the activity.
• Action a: Represented by a rounded rectangle, signifying an action or step within the activity.
• Action READY: Another rounded rectangle representing an action.
• End Node: A circle with a black dot inside, marking the end point of the activity.

Based on the common elements in both Act1 and Act2:

• The activity starts at the designated start node.
• It proceeds to action "a".
• Then it moves to action "READY".
• Finally, it reaches the end node, signifying completion.

There are no additional branches or loops that would allow for re-starting the activity or re-executing action "a" multiple times.

Analysis of Other Options:

• B. Initial and final nodes are optional... While it's true that initial and final nodes can be implicit in some cases, well-formed activity diagrams typically include them for clarity. Here, both diagrams have them explicitly.
• C. In diagram Act1. action a can get executed once... There's no basis to claim a difference in the number of executions of action "a" between the two diagrams.
• D. Diagram Act2 is incomplete... Both diagrams seem complete as they have proper start and end nodes, and the flow goes from start to finish without any ambiguity.

Therefore, considering the structure and execution flow, both Act1 and Act2 will end after the "READY" action, and no further signals will be accepted, making answer A the most accurate description.

The correct answer is E. 5. Based on the image you provided, the diagram depicts the following sequence of steps involved in creating an order:

• Create Order: This signifies the initiation of the order process.
• Fill Order Request: This step likely involves gathering information or processing details about the order.
• Create Invoice: An invoice is typically generated after an order is finalized.
• Notify Customer: The customer is informed about the order, possibly confirmation or receipt.

The key here is that the process starts with creating the order (step 1) and ends with notifying the customer (step 4). Steps 2 and 3 (filling the order request and creating an invoice) can happen concurrently and don't necessarily follow a specific order in relation to each other.

Therefore, following the logic of the sequence, there are five steps (0-based indexing), making E. 5 the most suitable answer.

An event occurrence in a UML Sequence Diagram refers to specific points in time where messages are sent or received. Each message send and each message receipt is counted as one event occurrence.

In the provided diagram for InteractionP, we have the following event occurrences:

• The send event ofm1().
• The receive event ofm1()by:Two.
• The send event ofm2().
• The receive event ofm2()by:One.

Counting these, we see that there are a total of 4 event occurrences specified in InteractionP.

Therefore, the correct answer is:

C. 4

• The diagram displays an activity labeled "Account Authentication".
• There are two main paths branching from the start of the activity:
• Both paths converge into a decision diamond labeled "Authentication Successful?".
• Depending on the outcome of the decision (Yes/No), the flow continues to either a "Grant Access" or "Deny Access" activity.

Explanation of why Option B is Correct:

This diagram accurately represents the scenario of account authentication where there are two alternative paths for validation: using a password or an OTP (One-Time Password). The decision point after these paths merges the flow for a final decision on granting or denying access based on successful authentication.

Comparison with Other Options:

• Option A, C, and D show different activity sequences that don't align with the two initial validation paths (password vs. OTP) and the subsequent decision point based on authentication success.

References

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