In the tutorial, JavaSampleApproach will guide how to create Spring RabbitMq Publish/Subcribe pattern by using fanout exchanges of RabbitMq and SpringBoot.
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Contents
I. Spring RabbitMq Publish/Subcribe pattern
We create a Publisher, and 3 Subcribers and using fanout exchanges of RabbitMQ for create a Publish/Subcribe Pattern System:
Flow messages:
– Publisher will send messages to the fanout exchange.
– The fanout exchange routes messages to all of the queues that are bound to it and the routing key is ignored.
– Subcribers instances recieves messages from the queues.
II. Practice
Technologies
– Java 8
– Maven 3.6.1
– Spring Tool Suite: Version 3.8.4.RELEASE
– Spring Boot: 1.5.4.RELEASE
– RabbitMQ
We create 2 SpringBoot projects {Publisher, Subcriber}:
Step to do:
– Create SpringBoot projects
– Create Publiser/Subcriber
– Setup RabbitMQ exchange, queues
– Run and check results
1. Create SpringBoot projects
Using Spring Tool Suite, create 2 Spring Starter Projects then add amqp dependency for both of them:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-amqp</artifactId> </dependency> |
– With SpringRabbitMqPubliser we add more web dependency for creating RestController:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> |
2. Create Publiser/Subcriber
2.1 Create Publisher
– Add RabbitMq configuration:
spring.rabbitmq.host=localhost spring.rabbitmq.port=5672 spring.rabbitmq.username=guest spring.rabbitmq.password=guest jsa.rabbitmq.exchange=jsa.fanout |
– Implement RabbitMq Publisher:
package com.javasampleapproach.rabbitmq.publisher; import org.springframework.amqp.core.AmqpTemplate; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; @Component public class Publisher { @Autowired private AmqpTemplate amqpTemplate; @Value("${jsa.rabbitmq.exchange}") private String exchange; public void produceMsg(String msg){ amqpTemplate.convertAndSend(exchange, "",msg); System.out.println("Send msg = " + msg); } } |
– Implement a sending restApi:
package com.javasampleapproach.rabbitmq.web; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController; import com.javasampleapproach.rabbitmq.publisher.Publisher; @RestController public class WebController { @Autowired Publisher publisher; @RequestMapping("/send") public String sendMsg(@RequestParam("msg")String msg){ publisher.produceMsg(msg); return "Done"; } } |
2.2 Create Subcriber
– Add RabbitMq configuration:
spring.rabbitmq.host=localhost spring.rabbitmq.port=5672 spring.rabbitmq.username=guest spring.rabbitmq.password=guest jsa.rabbitmq.queue=jsa.queue.1 |
– Create RabbitMq Subcriber:
package com.javasampleapproach.rabbitmq.subcriber; import org.springframework.amqp.rabbit.annotation.RabbitListener; import org.springframework.stereotype.Component; @Component public class Subcriber { @RabbitListener(queues="${jsa.rabbitmq.queue}") public void recievedMessage(String msg) { System.out.println("Recieved Message: " + msg); } } |
3. Setup RabbitMQ exchange, queues
Enable rabbitmq_management by cmd: rabbitmq-plugins enable rabbitmq_management --online
Go to: http://localhost:15672. Then login with user/password: guest/guest.
3.1 Add an exchange
Create a fanout exchange: jsa.fanout
3.2 Add queues
Create 3 RabbitMq queues {jsa.queue.1, jsa.queue.2, jsa.queue.3}:
Binding all above queues with the fanout exchange jsa.fanout:
4. Run and check results
Build 2 SpringBoot projects {Publisher, Subcriber} with the commandline: mvn clean install.
Run Publisher with commandline: mvn spring-boot:run, then send a message by a request: localhost:8080/send?msg=Hello World!
-> See status of the Queues:
Run 3 Subcriber instances which different configured values of jsa.rabbitmq.queue: {jsa.queue.1, jsa.queue.2, jsa.queue.3}.
See console logs of each Subcriber instances, we got the same message: ‘Recieved Message: Hello World!’.
-> Again, check status of the queues:
-> All messages has been consumed by Subcribers.
III. Sourcecode
SpringRabbitMqPublisher
SpringRabbitMqSubcriber
Last updated on May 21, 2019.