Microservices Microservice Design Patterns Questions and Answers

Question 1

An e-commerce platform is migrating from a monolithic architecture to microservices. They need a way for the front-end clients (web and mobile) to interact with the various new services like 'User', 'Product', and 'Order' without having to know the specific endpoint for each one. Which design pattern provides a single, unified entry point for all client requests and can also handle concerns like authentication, routing, and rate limiting?

Accepted Answer

API Gateway

Answer

The API Gateway pattern acts as a single entry point for all clients. It is responsible for request routing, composition, and protocol translation. It can also handle cross-cutting concerns such as authentication, SSL termination, and rate limiting, simplifying the client and the microservices themselves.

Question 2

A financial application involves a complex business transaction that spans multiple microservices: 'AccountService', 'TransactionService', and 'NotificationService'. To create a new transfer, the system must debit one account, credit another, record the transaction, and send a notification. If any of these steps fail, the entire operation must be rolled back to maintain data consistency. Which design pattern is best suited for managing this distributed transaction?

Accepted Answer

Saga Pattern

Answer

The Saga pattern is designed to manage data consistency across microservices in a distributed transaction. It uses a sequence of local transactions where each transaction updates data within a single service and publishes an event to trigger the next transaction. If a step fails, the saga executes compensating transactions to undo the preceding work, ensuring eventual consistency without the tight coupling and blocking nature of Two-Phase Commits.

Question 3

Which of the following is a primary benefit of implementing the 'Database per Service' design pattern in a microservices architecture?

Accepted Answer

Increased service autonomy and loose coupling.

Answer

The Database per Service pattern ensures that each microservice has its own private database, which is not accessible by other services. This enforces loose coupling, as changes to one service's database schema do not directly impact others. It grants each service the autonomy to choose its own database technology and evolve independently.

Question 4

A development team is working on a legacy monolithic application and wants to gradually migrate its functionality to a new microservices architecture without performing a risky 'big bang' rewrite. They plan to incrementally build new microservices and route traffic to them, while the old monolith continues to handle the remaining functionality. Which pattern facilitates this gradual migration strategy?

Accepted Answer

Strangler Fig Pattern

Answer

The Strangler Fig pattern is an architectural approach for incrementally migrating a legacy system. It involves creating a new application (the 'strangler') around the old one and gradually replacing pieces of the monolith's functionality with new microservices. An intermediary layer, often a proxy or API gateway, intercepts requests and routes them to either the new microservice or the old monolith, allowing for a safe, phased migration.

Question 5

In a social media application, the service responsible for handling user posts has significantly different requirements for writing data (creating a post) versus reading data (viewing a feed). The read operations are far more frequent and require complex queries and denormalized views for performance, while write operations are simpler but must be highly consistent. Which pattern would be most effective for optimizing these distinct workloads?

Accepted Answer

Command Query Responsibility Segregation (CQRS)

Answer

The Command Query Responsibility Segregation (CQRS) pattern separates the models for updating data (Commands) from the models for reading data (Queries). This allows the read and write sides to be scaled, optimized, and developed independently. For example, the write side can use a normalized schema for consistency, while the read side can use a denormalized view optimized for fast queries.

Microservices Practice Test

Microservices Practice Test

Microservices Microservice Design Patterns Questions and Answers