Business Layer

What is the primary purpose of the Business Layer (Domain Layer) in a software system?. To manage UI rendering and user interactions. To encapsulate and execute the core business rules of the application. To store and retrieve data from the database.

The Business Layer should be responsible for saving objects directly into the database. True. False.

Which description best matches the Business Layer?. The layer that coordinates domain rules and ensures business correctness. The layer that renders HTML, JSON, and other responses. he layer that schedules server processes and handles logging.

What does the Business Layer mainly contain?. Business logic, rules, domain models, and domain services. CSS styles, templates, and controllers. SQL queries, repositories, and database models.

The Business Layer is the “heart” of a layered architecture because it defines the system’s behavior and rules. True. False.

What is the main motivation for using a Business Layer in software architecture?. To reduce the number of controllers. To keep business rules separate from technical details. To avoid using databases.

One of the core intents of the Business Layer is to create a single source of truth for all business rules. True. False.

Why does the Business Layer improve maintainability?. It reduces the number of endpoints in the application. It isolates business logic, allowing independent changes without modifying UI or data layers. It eliminates the need for validators.

Which of the following problems does the Business Layer help solve?. Overloading the database with too many tables. Mixing domain rules with UI concerns or persistence code. Slow network connections.

Another motivation of the Business Layer is to ensure that domain rules remain consistent even when the infrastructure changes (e.g., switching from SQL to NoSQL). True. False.

Which of the following is a core responsibility of the Business Layer?. Rendering UI pages. Enforcing business rules and policies. Managing database connections.

One responsibility of the Business Layer is to maintain the integrity of the domain through invariants and validations. True. False.

Which action correctly reflects what the Business Layer should handle?. Deciding how to format a JSON response. Calculating discounts, taxes, or business-specific rules. Managing authentication tokens.

Why is coordinating domain operations considered a responsibility of the Business Layer?. Because the Business Layer controls the UI flow. Because domain operations may involve multiple entities and business rules that must be applied consistently. Because the Business Layer stores user sessions.

The Business Layer should protect the domain from invalid states by preventing operations that break business constraints. True. False.

Which of the following best defines a Domain Entity?. A class that represents a database table. An object with a unique identity that persists throughout the system’s lifecycle. A visual component used in the presentation layer.

A Value Object represents something defined by its attributes, not by identity. True. False.

What is the main purpose of an Aggregate in domain modeling?. To group related domain objects and enforce consistency rules. To handle database transactions. To map entities to DTOs.

What is a Domain Service?. A technical service for handling HTTP requests. A stateless operation that represents domain logic not naturally belonging to any single entity. A utility class used for converting data between layers.

A bounded context helps limit the scope of your domain by defining clear boundaries where specific models and rules apply. True. False.

In a typical Business Layer UML diagram, which component is usually placed at the center of the structure?. Controllers. Domain Entities and Aggregates. Database Repositories.

In UML diagrams of the Business Layer, the arrows typically show that application services depend on domain entities and domain services—not the other way around. True. False.

In a UML diagram for the Business Layer, what does the Aggregate Root usually control?. Access to the database. Access to all other objects inside the Aggregate. Communication with the presentation layer.

What type of relationship is typically shown between an Application Service and a Repository in UML diagrams?. Inheritance. Composition. Dependency.

UML diagrams for the Business Layer often illustrate that Value Objects have immutable properties and no identity. True. False.