Learning Java microservices for back-end development

Microservices are generally used to design and develop applications as a collection of independent services that can communicate with others through APIs. Back-end microservices, in particular, are key to building large-scale, distributed systems that are scalable and efficient.

Learning Java is a prominent choice among developers that can also be utilized to build flexible microservices by breaking down complex systems into smaller, independent services. Java microservices allow developers to create adaptable applications by breaking down complex systems into smaller, independent services. Here, we will cover the key aspects of the architecture of microservices development using Java.

What are back-end microservices?

Back-end microservices specifically operate on the server side of an application. They handle operations such as data storage, business logic, and interactions with other back-end systems. The main focus of back-end microservices is being responsible for the core functionalities that power the application but aren’t directly associated with the user interface or client-side logic.

Some examples of services they deal with include user authentication, payment processing, or data analytics that specifically run on the server.

Java microservices for back-end development

Back-end microservices built with Java involve developing the server-side components of applications designed to operate as independent services. This includes setting up APIs, managing data, and ensuring services communicate effectively.

Here are some key components you should know about:

Frameworks and libraries

Spring Boot is a robust Java framework that simplifies building production-ready applications. It provides features such as dependency injection, auto-configuration, and embedded web servers such as Tomcat. Moreover, Jakarta EE, formerly Java EE, is a set of specifications extending the Java SE with APIs for features such as distributed computing and web services.

Data access

Java Persistence API (JPA) is used for object-relational mapping (ORM) to manage relational data in Java applications. A popular implementation is Hibernate. On the other hand, Spring Data simplifies data access by providing repositories and other abstractions that support SQL and NoSQL databases.

API development

When it comes to RESTful APIs, implementing the REST principles for service endpoints uses Spring Web or JAX-RS (Jakarta EE’S RESTful web services). GraphicQL is an alternative to REST for API development, which allows clients to request specific data structures.

Inter-service communication

There are two types of communication: synchronous and asynchronous. Synchronous communication uses HTTP/REST or gRPC for real-time communication between microservices. Meanwhile, asynchronous communication utilizes message brokers such as RabbitMQ or Apache Kafka for decoupled and resilient service interactions.

Factors to consider: Back-end Java microservices

Defining architecture and design

Start identifying which domain-specific functionality each microservice is going to be responsible for.

• Event-driven or request-driven

Depending on your architecture, you must determine if the services will be event-driven using message brokers such as Kafka or request-driven, where RESTful APIs are typically used.

• Database design

Back-end services generally manage databases, and at this stage, you have to ensure each service has its dedicated database or schema, following the database per service pattern. You can use SQL for transactional data and NoSQL for high-volume or unstructured data.

• Data consistency

Consider eventual consistency and choose between saga or two-phase commit patterns for transactional data.

Designing back-end APIs

In this step, you’ll design REST APIs, starting with the API endpoints and HTTP methods. You can use Swagger to document the API, followed by data transfer objects (DTOs) to standardize the data exchanged. You must also version your APIs to support backend compatibility and decide how the backend services will communicate internally.

Implementing backend functionality

You must implement core business rules using service classes for the business logic layer. You can apply practices such as layering, controller service, and repository. Using dependency injection will allow for decoupling logic and improving testability.

You may use JPA/Hibernate or Spring Data JPA to interact with relational databases in the data access layer. MongoDB can be integrated for non-relational databases, or Cassandra can use Spring Data NoSQL modules. Transactions can ensure data integrity.

Scaling and resilience

Back-end microservices are scaled horizontally by increasing the number of instances to ensure efficient handling of higher loads. To handle partial failures, you can implement resilience patterns using Hystrix or Resillience4j for circuit breaking, retry mechanisms, and fallback logic.

CI/CD and deployment

Continuous integration (CI) involves setting up a pipeline, such as Jenkins or GitLab CI, to automatically run tests, build Docker images, and package services. Moreover, Docker can be used to containerize each back-end microservice.

Final words

There are many other considerations when developing Java microservices for back-end development, such as CI/CD and deployment, logging, monitoring, tracing, testing, security implementation, and database integration.

Java can help developers gain access to powerful frameworks such as Spring Boot and build efficient back-end microservice architectures that are an essential part of modern, cloud-native applications.