gushakov/axon-multi

Playground application demonstrating DDD, EDA, CQRS with Axon

Axon Multi-services

🚧 Attention: under construction 🚧

⚠️ Note, in AssignPrivateAddressSaga.java there is a use of QueryGateway for validation of the address assigment. This goes against CQRS principles stating that a Saga must not access the read-model (or projections). See this question and answer for more details.

Introduction

Playground application with uses Axon framework to demonstrates a way of building a distributed event-driven system around the concepts of domain-driven design and CQRS.

Application structure

There are several modules, they are standalone Spring Boot applications or libraries:

• common: module containing configuration (Maven dependencies) common to other modules
• core: module with all commands and events shared by other modules
• db: H2 file database running as a TCP server
• address: microservice around "address" aggregate
• person: microservice around "person" aggregate
• saga: Saga implementation of a business transaction (private address assignment)

Axon configuration

• Using Axon Server version 4.1 without event sourcing infrastructure
• Aggregates, projections, and Sagas persist their states in the separate schemas of the central H2 database

CQRS and messaging infrastructure

This is the overview of the system:

API

• http://localhost:8080/swagger-ui.html (Person)
• http://localhost:8081/swagger-ui.html (Address)

Saga

This is how assigning private address to a person Saga proceeds:

Build and run with Docker

• Run mvn package on the project
• Run docker-compose up

H2 database

• Access H2 console at http://localhost:8079/h2-console
• Use Server configuration
• JDBC URL: jdbc:h2:tcp://localhost:9090/./axondb;IFEXISTS=true;DB_CLOSE_ON_EXIT=FALSE

Links and resources used in this project

• Configuring Axon Server for Docker
• Error Handling for REST with Spring
• Build a REST API with Spring
• Spring Boot with Docker
• Access the Same In-Memory H2 Database in Multiple Spring Boot Applications
• How to Make Legacy Code Reactivee
• #HOWTO: Best Practices for Flyway and Hibernate with Spring Boot

axon-multi's Issues

can not build

: Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'commonAxonConfig': Injection of autowired dependencies failed; nested exception is org.springframework.amqp.AmqpConnectException: java.net.ConnectException: Connection refused
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:380) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1395) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:849) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
at com.github.axonmulti.person.PersonSpringBootApplication.main(PersonSpringBootApplication.java:21) ~[classes/:na]
Caused by: org.springframework.amqp.AmqpConnectException: java.net.ConnectException: Connection refused
at org.springframework.amqp.rabbit.support.RabbitExceptionTranslator.convertRabbitAccessException(RabbitExceptionTranslator.java:62) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.amqp.rabbit.connection.AbstractConnectionFactory.createBareConnection(AbstractConnectionFactory.java:509) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.amqp.rabbit.connection.CachingConnectionFactory.createConnection(CachingConnectionFactory.java:682) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.amqp.rabbit.connection.ConnectionFactoryUtils.createConnection(ConnectionFactoryUtils.java:214) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.amqp.rabbit.core.RabbitTemplate.doExecute(RabbitTemplate.java:2061) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.amqp.rabbit.core.RabbitTemplate.execute(RabbitTemplate.java:2035) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.amqp.rabbit.core.RabbitTemplate.execute(RabbitTemplate.java:2015) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at org.springframework.amqp.rabbit.core.RabbitAdmin.declareExchange(RabbitAdmin.java:231) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
at com.github.axonmulti.common.config.CommonAxonConfig.configure(CommonAxonConfig.java:59) ~[classes/:na]
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:578) ~[na:na]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredMethodElement.inject(AutowiredAnnotationBeanPostProcessor.java:708) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:374) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
... 17 common frames omitted
Caused by: java.net.ConnectException: Connection refused
at java.base/sun.nio.ch.Net.pollConnect(Native Method) ~[na:na]
at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:672) ~[na:na]
at java.base/sun.nio.ch.NioSocketImpl.timedFinishConnect(NioSocketImpl.java:542) ~[na:na]
at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:585) ~[na:na]
at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327) ~[na:na]
at java.base/java.net.Socket.connect(Socket.java:666) ~[na:na]
at com.rabbitmq.client.impl.SocketFrameHandlerFactory.create(SocketFrameHandlerFactory.java:60) ~[amqp-client-5.4.3.jar:5.4.3]
at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:1102) ~[amqp-client-5.4.3.jar:5.4.3]
at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:1054) ~[amqp-client-5.4.3.jar:5.4.3]
at com.rabbitmq.client.ConnectionFactory.newConnection(ConnectionFactory.java:994) ~[amqp-client-5.4.3.jar:5.4.3]
at org.springframework.amqp.rabbit.connection.AbstractConnectionFactory.createBareConnection(AbstractConnectionFactory.java:462) ~[spring-rabbit-2.1.4.RELEASE.jar:2.1.4.RELEASE]
... 29 common frames omitted

Process finished with exit code 1