Summary

In this chapter, we have been introduced to Spring Boot and complementary open source tools that can be used to build cooperating microservices.

Spring Boot is used to simplify the development of Spring-based, production-ready applications, such as microservices. It is strongly opinionated in terms of how to set up both core modules from the Spring Framework and third-party tools. Using Spring WebFlux, we can develop microservices that expose reactive, that is, non-blocking, REST services. To document these REST services, we can use springdoc-openapi to create OpenAPI-based documentation for the APIs. If we need to persist data used by the microservices, we can use Spring Data, which provides an elegant abstraction for accessing and manipulating persistent data using entities and repositories. Spring Data’s programming model is similar, but not fully portable between different types of databases, for example, relational, document, key-value, and graph databases.

If we prefer sending messages asynchronously between our microservices, we can use Spring Cloud Stream, which provides a streaming abstraction over messaging. Spring Cloud Stream comes with out-of-the-box support for Apache Kafka and RabbitMQ but can be extended to support other messaging brokers using custom binders. Finally, Docker makes the concept of containers as a lightweight alternative to virtual machines easy to use. Based on Linux namespaces and control groups, containers provide isolation similar to what traditional virtual machines provide, but with a significantly lower overhead in terms of CPU and memory usage.

In the next chapter, we will take our first small steps, creating microservices with minimalistic functionality using Spring Boot and Spring WebFlux.