Asynchronous message communication under Spring Cloud microservices

With the rise of cloud computing and big data, microservice architecture is widely used in enterprise systems. As an important implementation tool for microservice architecture, Spring Cloud provides a variety of solutions for realizing communication under microservice architecture. This article will focus on the asynchronous message communication solution under Spring Cloud microservices, hoping to provide some ideas and reference for everyone to solve the message communication problems under the microservice architecture.

1. Background of microservice asynchronous message communication

Under the microservice architecture, the service is split into multiple microservices for independent development, independent deployment and independent maintenance. There must be interaction and communication. However, traditional RPC calls or HTTP requests will degrade system performance due to long response times in high concurrency and big data scenarios. Therefore, asynchronous message communication is widely used in microservices as an excellent solution and efficiently supports Communication between different microservices.

2. Asynchronous message communication solutions under Spring Cloud

In Spring Cloud, there are two commonly used asynchronous message communication solutions: Spring Cloud Stream and Spring Cloud Bus.

1. Spring Cloud Stream

Spring Cloud Stream is a framework provided by Spring Cloud for building message-driven microservices. It is built on Spring Boot and Spring Integration and can easily connect various message broker services. Spring Cloud Stream implements asynchronous message communication based on the publish/subscribe model (Publish/Subscribe).

The Spring Cloud Stream workflow is as follows:

① The producer generates messages and publishes them to Spring Cloud Stream;
② Spring Cloud Stream sends the messages to the intermediate agent (Message Broker);
③ The consumer subscribes to the information from the intermediate agent and notifies Spring Cloud Stream when it receives the message. Spring Cloud Stream then delivers the message to the corresponding consumer.

Spring Cloud Stream uses message broker services such as Apache Kafka and RabbitMQ, which has the characteristics of high reliability, high concurrency and high scalability. Its use process is very simple. You only need to introduce the corresponding dependencies and configure the message agent it uses. The sample code to implement a message service is as follows:

// 引入Spring Cloud Stream依赖
<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-stream-kafka</artifactId>
</dependency>
 
// 在应用程序属性文件中设置连接的kafka代理
spring.cloud.stream.kafka.binder.brokers=kafka.example.com:9092
spring.cloud.stream.kafka.binder.zkNodes=zookeeper.example.com
spring.cloud.stream.kafka.binder.defaultBrokerPort=9092
spring.cloud.stream.kafka.binder.defaultZkPort=2181

2. Spring Cloud Bus

Spring Cloud Bus is a mechanism for propagating state changes in a distributed system. It can Let messages pass between the various microservices that make up the system. Spring Cloud Bus uses a message broker to connect various microservices and uses a lightweight message type to complete the transmission of event status. Different from Spring Cloud Stream, Spring Cloud Bus is more used for messaging and state sharing within the system.

Spring Cloud Bus workflow is as follows:

① Trigger events that can affect the state on Spring Cloud Bus through HTTP/HTTPS requests (for example: POST method, PATCH method or DELETE method) ;
② Spring Cloud Bus receives the event request and stores the content of the event;
③ Broadcasts the event status in Spring Cloud Bus to the entire distributed system through the message agent;
④ Each microservice listens for messages Event status in the agent, and synchronously changes its own status in real time when the event status changes.

Spring Cloud Bus uses RabbitMQ or Kafka as the message proxy server, which has the characteristics of high scalability and high reliability. Spring Cloud Bus is very simple to use. You only need to add the corresponding configuration in the application properties file. The sample code to implement a message service is as follows:

// 添加依赖
<dependency>
   <groupId>org.springframework.cloud</groupId>
   <artifactId>spring-cloud-starter-bus-amqp</artifactId>
</dependency>
 
// 在应用程序属性文件中设置RabbitMQ地址
spring.rabbitmq.host=localhost
spring.rabbitmq.virtual-host=/
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

3. Summary

Spring Cloud is one of the most popular implementation solutions in the current microservice architecture. Using Spring Cloud to implement asynchronous message communication has many an advantage. This article introduces the commonly used asynchronous message communication solutions under Spring Cloud: Spring Cloud Stream and Spring Cloud Bus, and introduces how to use them in applications through simple code examples. I hope this article can help everyone better apply the microservice architecture in practice and improve the performance and stability of the system.

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