Test your knowledge of essential microservices design patterns with these interview-style questions, covering key concepts like scalability, communication, fault tolerance, and best practices for distributed systems. This quiz helps you assess your understanding of common patterns used to build reliable and maintainable microservices architectures.
Which decomposition pattern focuses on splitting a large application into smaller, business-capable services based on domain boundaries?
Explanation: Domain-Driven Design decomposition emphasizes dividing the system into services along meaningful business domains, enabling each microservice to focus on a specific capability. Database per Service deals with data ownership, not service responsibilities. Layered decomposition refers to organizing systems by technical layers rather than business domains. API Gateway decomposition is about routing and aggregation, not service boundaries. Only Domain-Driven Design specifically prioritizes decomposition by business function.
Why is the API Gateway pattern commonly used in microservices architecture?
Explanation: The API Gateway pattern enables a centralized and unified entry for all client interactions, simplifying client-side logic and managing cross-cutting concerns like authentication and throttling. Connecting microservices directly with databases risks tight coupling and isn't the gateway's role. Monitoring configuration is a separate concern best addressed within each service. The gateway does not handle distributed transaction synchronization—other patterns manage data consistency.
What is a main advantage of using the Database per Service pattern in microservices?
Explanation: Database per Service provides loose coupling by allowing each microservice to manage its own database, which prevents unintended dependencies between services. Shared databases can compromise isolation and create tight coupling. Reducing API usage limits integration and doesn't address separation. Although querying across services becomes more complex, that's a trade-off for improved autonomy and scalability.
Which problem does the Circuit Breaker pattern aim to solve in a distributed system?
Explanation: The Circuit Breaker pattern protects systems from repeated failures by temporarily blocking calls to an unresponsive or overloaded service, thus avoiding cascading failures and letting the problematic service recover. It does not help with schema migrations or automatically replacing APIs. Synchronizing time between services is a distinct challenge, separate from fault tolerance addressed by the Circuit Breaker.
How does the Saga pattern manage transactions in microservices architectures?
Explanation: The Saga pattern manages distributed transactions by chaining local transactions together, with compensating actions to undo work if part of the transaction fails. Single-phase commit is impossible in fully distributed systems due to autonomy. Storing all states in one place or locking resources long-term undermines microservices principles, as they reduce scalability and introduce bottlenecks.
A company wants to migrate functionality from a monolith to microservices gradually. Which pattern should they use?
Explanation: The Strangler pattern supports incremental migration by slowly replacing pieces of a monolithic system with new microservices, allowing old and new components to coexist. The Bulkhead pattern isolates system resources for stability, not migration. CQRS is about separating read and write models. The Sidecar pattern is for deploying supporting components; it doesn't manage application migration.
What is the primary purpose of the CQRS (Command Query Responsibility Segregation) pattern in microservices?
Explanation: CQRS separates command (write) and query (read) responsibilities, allowing for optimized data models and operations for each case, which can improve performance and scalability. Unified models do not address this concern. While CQRS may help with event sourcing and audit logs, that's not its primary goal, and direct client-database access is not recommended in microservices architectures.
Why is the Bulkhead pattern valuable in microservices, especially as the system scales?
Explanation: The Bulkhead pattern partitions resources like threads or database connections, so if one section fails, others remain unaffected, enhancing system resilience. Using the same protocol improves compatibility but doesn't prevent cascading failures. Combining endpoints relates to gateway patterns, and triggering retries is a separate concern often managed by the Retry pattern.
In a dynamic microservices environment, what does the Service Discovery pattern help achieve?
Explanation: Service Discovery allows services to find and interact with each other by automatically registering and resolving instance locations, which is vital as services scale and move. It doesn't manage API versioning, encryption, or directly limit the number of services; those concerns are handled by other architectural patterns or tools.
What is a defining characteristic of the Event Sourcing pattern when used with microservices?
Explanation: Event Sourcing captures all changes as a series of immutable events, enabling full reconstruction of an entity's state and supporting auditing or rollback. Storing only the latest state loses important history. Allowing external alteration of logs breaks integrity. Discarding historical data contradicts the purpose of event sourcing, which is to retain all changes.