Microservices with Spring Cloud

A deep-dive into the Microservice architectural style, and how to implement it with Spring technologies.
(Updated version of https://github.com/quickheaven/Microservices-With-Spring)

What are Microservices

Best describe as:

• An architectural style
• An alternative to more traditional 'monolithic' applications
• Decomposition of single system into a suite of small services, each running as independent processes and intercommunicating via open protocols.
• Fine Grained SOA - Adrian Cockroft (Netflix)

Spring Boot

Spring boot is all about getting a Java Spring application up and running very quickly.

Running Spring Boot:

• Spring Application
  • Created Spring Application Context
• Created Spring Application Context @SpringBootApplication
  • Combination of @Configuration (Java equivalent of file
  • ... And @ComponentScan (Looks for @Components)
  • ... And @EnableAutoConfiguration (Examines ApplicationContext & classpath; Creates missing beans based on intelligent defaults)

Spring Cloud

The goal is to address the needs of cloud based applications. Spring Cloud is a sub-project within Spring IO Umbrella. And is itself an umbrella project. Spring Cloud addresses common patterns in distributed computing. Spring Cloud is based on Spring Boot.

Spring and NETFLIX since 2017

Eureka -> Eureka
Archaius -> Spring Cloud Config
Ribbon -> Spring Cloud Load Balancer
Zuul -> Spring Cloud Gateway
Hystrix -> Resilience4J / Spring Cloud Circuit Breaker
Hystrix Dashboard -> Micrometer
Turbine -> Micrometer

DevTools

Optional dependency. Automatically restarts applications aftermost code changes.

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-devtools</artifactId>
	<optional>true</optional>
</dependency>

Spring Cloud Configuration

(Centralized Version Configuration) Provides centralized, externalized, secured, easy-to-reach source of application configuration.

Spring Cloud Bus

Provides simple way to notify clients to config changes

Spring Cloud Netflix Eureka

Service Discovery - Allows applications to register themselves as clients