How do microservices communicate with each other?

Through lightweight communication protocols such as:

Synchronous: HTTP/REST, gRPC

Asynchronous: Message brokers like RabbitMQ, Apache Kafka, or AWS SQS

What is the difference between @Controller and @RestController?
• @Controller is used to define a Spring MVC controller that returns a view (e.g., JSP, Thymeleaf).
• @RestController is a convenience annotation that combines @Controller and @ResponseBody. It is used when the controller returns data directly (e.g., JSON, XML) instead of a view.

What are Spring Profiles? How are they useful?
• Spring Profiles allow you to define different configurations for different environments (e.g., dev, test, prod).
• They are activated using spring.profiles.active in application.properties or via environment variables.
• Example: @Profile("dev") ensures a bean is only loaded in the dev environment.

Explain the difference between @Component, @Repository, and @Service.
• @Component: Generic annotation for Spring-managed components.
• @Repository: Specialized for Data Access Objects (DAO). It provides exception translation.
• @Service: Specialized for the service layer. Indicates a service class for business logic.

What is the difference between @Component and @Configuration in Spring?
• @Component: Marks a class as a Spring-managed bean. It’s generally used for classes like services, repositories, or controllers.
• @Configuration: A specialized @Component used for defining bean creation methods explicitly using @Bean. It ensures singleton behavior for beans defined within the class.

What is the difference between @RestController and @Controller?

Answer:

@Controller: A specialization of @Component used for defining controllers in Spring MVC. Typically used in conjunction with @RequestMapping to define request-handling methods. It returns views (HTML pages) via ModelAndView.

@RestController: Combines @Controller and @ResponseBody. It is used to create RESTful web services and automatically serializes Java objects into JSON or XML.

How does Spring Boot auto-configuration work?

Answer:

Spring Boot uses the @EnableAutoConfiguration annotation (or indirectly via @SpringBootApplication) to configure beans based on the libraries on the classpath and properties defined in application.properties or application.yml.

The spring.factories file inside META-INF lists all the auto-configuration classes, which are conditionally applied using @ConditionalOnClass, @ConditionalOnProperty, etc.

What is the difference between @Component, @Repository, and @Service?

Answer:

@Component: A generic stereotype annotation for any Spring-managed component.

@Repository: A specialization of @Component used to indicate a Data Access Object (DAO). Automatically translates database exceptions into Spring exceptions.

@Service: A specialization of @Component used to indicate a service layer bean. It is used to encapsulate business logic.

How does Spring Boot handle exceptions in REST APIs?

Answer:

Use @ControllerAdvice to define a global exception handler.

Handle exceptions with @ExceptionHandler methods in the advice class.

Return meaningful HTTP status codes and error messages in the response body.

What is the purpose of the @SpringBootApplication annotation?

Answer:

It is a combination of three annotations:

1. @SpringBootConfiguration: Similar to @Configuration.


2. @EnableAutoConfiguration: Enables Spring Boot's auto-configuration.


3. @ComponentScan: Scans the package where the application class resides.

What is the use of @Conditional annotations in Spring Boot?

Answer:

Spring Boot uses @Conditional annotations to enable conditional bean creation.

Examples:

@ConditionalOnClass: Bean is created only if a specific class is on the classpath.

@ConditionalOnProperty: Bean is created only if a specific property is defined in the configuration.

Today's demo session will cover Spring Boot features, and the trainer will conduct a quiz on Spring Boot basics and its key features. Don't miss it! 🚀

🔥 Spring Boot & Microservices
🔥 Real Time Java Project
👨‍✈️ Trainer : Mr. Bhaskar

Day 3 : 20th Feb @ 9 OM IST
👉 Enroll Now for Meeting Details : https://bit.ly/4gyBoIV

📞 Join In WhatsApp : https://bit.ly/3Rbgvd1

Back Up Videos
Day 1 : https://youtu.be/TgPi69_iGRg
Day 2 : https://youtu.be/XEPQpuqBCAM