Question 1

​The starting point for identifying messages in detailed design of a use case is always the SSD.

Accepted Answer

The SSD (System Sequence Diagram) is a diagram that shows the interactions between actors and the system it interacts with. It is used to identify the messages needed to accomplish the use case scenarios described in the detailed design. Therefore, the starting point for identifying messages in the detailed design of a use case is always the SSD.

Question 2

​The activation lifeline is depicted by a vertical dashed line under an object.

Accepted Answer

The activation lifeline in a sequence diagram is depicted by a thin rectangle on a lifeline (not a dashed line) to show that an object is active.

Question 3

​Adding a use case controller to a sequence diagram is an example of applying a design pattern.

Accepted Answer

The use case controller is a common design pattern used in sequence diagrams to represent the control flow between multiple use cases. It helps to organize the sequence diagram and clarify the interactions between different actors and use cases. Therefore, adding a use case controller to a sequence diagram is an example of applying a design pattern.

Question 4

​The true/false condition on a message indicates whether the method on the destination object will execute.

Accepted Answer

The true/false condition on a message typically refers to a conditional statement in programming, not whether a method on the destination object will execute. Method execution depends on the method call and object state, not a true/false condition directly on the message.

Question 5

​Since updating a design class diagram is done after the use case realization is complete,visibility information is no longer necessary.

Accepted Answer

Visibility information specifies the access level of attributes and operations in a class, and is relevant even after the use case realization is complete, as it impacts the implementation and documentation of the system. Therefore, it is still important to update the visibility information in the design class diagram.

Question 6

​The perfect technology assumption means not to worry about issues such as user security.

Accepted Answer

The answer of ​The perfect technology assumption means not to...

Question 7

​The code "if (someObject == null)" is part of the factory pattern.

Accepted Answer

The answer of ​The code "if (someObject == null)" is...

Question 8

​A loop or repeating message or messages in a sequence diagram is depicted by a rectangle box.

Accepted Answer

A loop or repeating message or messages in a sequence diagram is indeed depicted by a rectangle box. This box is also called a loop fragment and is used to represent a loop in the sequence diagram. The loop fragment contains the condition for executing the loop and the messages that are repeated inside the loop.

Question 9

​The first-cut DCD includes method signatures.

Accepted Answer

The answer of ​The first-cut DCD includes method signatures....

Question 10

​Dependency relationships cannot exist between classes within packages.

Accepted Answer

Dependency relationships can exist not only between classes within a package, but also between classes in different packages.

Question 11

​The perfect memory assumption means that there is always adequate memory to execute the program.

Accepted Answer

The perfect memory assumption refers to the theoretical assumption that memory operations (allocations, deallocations, reads, and writes) in a program execute without errors such as memory leaks, dangling pointers, or buffer overflows, rather than the availability of adequate memory.

Question 12

​An interaction diagram is a subclass of a sequence diagram.

Accepted Answer

An interaction diagram is not a subclass of a sequence diagram; rather, sequence diagrams are a type of interaction diagram. Interaction diagrams include both sequence diagrams and collaboration diagrams, which are used to show how objects interact in a system.

Question 13

​The controller object is usually part of view layer.

Accepted Answer

The controller object is usually part of the controller layer, not the view layer. It acts as an intermediary between the model and the view, controlling the flow of data and logic between them.

Question 14

​A timeline on a communication diagram indicates the sequence of the messages.

Accepted Answer

A communication diagram does not use a timeline to indicate the sequence of messages; instead, it shows the interactions between objects through numbered messages to indicate their sequence.

Question 15

​Links on communication diagram simple show the flow of messages and are not the associations between classes.

Accepted Answer

Communication diagrams depict how objects interact and exchange messages at runtime, and the links between the objects represent the message flow. These links do not represent associations between classes. Associations between classes are represented by lines with arrows at the ends in class diagrams.

Question 16

​There are two preferred methods to accessing the database. One is to have newly instantiated object call the data access object. The other is to let the controller access the data access object.

Accepted Answer

The answer of ​There are two preferred methods to accessing...

Question 17

​Design class diagrams and interaction diagrams should be developed independent of each other.

Accepted Answer

Design class diagrams and interaction diagrams are complementary; class diagrams show the static structure of the system, including classes and their relationships, while interaction diagrams (such as sequence diagrams and communication diagrams) show how instances of these classes interact over time to perform a function. Developing them in tandem ensures consistency and completeness in the design.

Question 18

​The perfect solution assumption means that we do not worry about exception conditions.

Accepted Answer

The perfect solution assumption implies that in the process of designing or analyzing algorithms, we temporarily ignore potential complications such as error conditions or exceptional cases, focusing instead on the ideal scenario where everything operates as expected.

Question 19

​The best technique for accessing the database when multiple objects are needed is just to let the data access object instantiate objects.

Accepted Answer

This approach is known as the "Active Record" pattern and is commonly used in object-oriented programming for data persistence. It allows for the creation, updating, and deletion of objects in the database, as well as querying the database for multiple objects at once. In this approach, the data access object is responsible for mapping between the objects in the code and the rows in the database.

Question 20

​The initial version of a communication diagram contains view layer and business layer.

Accepted Answer

The initial version of a communication diagram typically contains the actors or external systems involved in the system, as well as the messages or interactions between them. It may also include a rough layout of the components or modules of the system, but it typically does not separate out the view layer and business layer specifically.

Quiz 13: Object-Oriented Design: Use Case Realization

​The starting point for identifying messages in detailed design of a use case is always the SSD.

​The activation lifeline is depicted by a vertical dashed line under an object.

​Adding a use case controller to a sequence diagram is an example of applying a design pattern.

​The true/false condition on a message indicates whether the method on the destination object will execute.

​Since updating a design class diagram is done after the use case realization is complete,visibility information is no longer necessary.

​The perfect technology assumption means not to worry about issues such as user security.

​The code "if (someObject == null)" is part of the factory pattern.

​A loop or repeating message or messages in a sequence diagram is depicted by a rectangle box.

​The first-cut DCD includes method signatures.

​Dependency relationships cannot exist between classes within packages.

​The perfect memory assumption means that there is always adequate memory to execute the program.

​An interaction diagram is a subclass of a sequence diagram.

​The controller object is usually part of view layer.

​A timeline on a communication diagram indicates the sequence of the messages.

​Links on communication diagram simple show the flow of messages and are not the associations between classes.

​There are two preferred methods to accessing the database. One is to have newly instantiated object call the data access object. The other is to let the controller access the data access object.

​Design class diagrams and interaction diagrams should be developed independent of each other.

​The perfect solution assumption means that we do not worry about exception conditions.

​The best technique for accessing the database when multiple objects are needed is just to let the data access object instantiate objects.

​The initial version of a communication diagram contains view layer and business layer.

The starting point for identifying messages in detailed design of a use case is always the SSD.

The activation lifeline is depicted by a vertical dashed line under an object.

Adding a use case controller to a sequence diagram is an example of applying a design pattern.

The true/false condition on a message indicates whether the method on the destination object will execute.

Since updating a design class diagram is done after the use case realization is complete,visibility information is no longer necessary.

The perfect technology assumption means not to worry about issues such as user security.

The code "if (someObject == null)" is part of the factory pattern.

A loop or repeating message or messages in a sequence diagram is depicted by a rectangle box.

The first-cut DCD includes method signatures.

Dependency relationships cannot exist between classes within packages.

The perfect memory assumption means that there is always adequate memory to execute the program.

An interaction diagram is a subclass of a sequence diagram.

The controller object is usually part of view layer.

A timeline on a communication diagram indicates the sequence of the messages.

Links on communication diagram simple show the flow of messages and are not the associations between classes.

There are two preferred methods to accessing the database. One is to have newly instantiated object call the data access object. The other is to let the controller access the data access object.

Design class diagrams and interaction diagrams should be developed independent of each other.

The perfect solution assumption means that we do not worry about exception conditions.

The best technique for accessing the database when multiple objects are needed is just to let the data access object instantiate objects.

The initial version of a communication diagram contains view layer and business layer.