Axon: Setting up Distributed Command Bus

Question

Edit: Found a solution, I will update this post

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Edit 2: The problem was that I defined my Commands and Events inside the src folder of my first and second microservice. The first microservice shot a com.myApplication.PaymentManagementService.commands.ApproveOrderCommand-command, while the command handler in the second microservice expected a com.myApplication.OrderManagementService.commands.ApproveOrderCommand-command.

I fixed the redundancy by lifting the commands and events a few hierarchy levels into a common api-folder that both services can access. Now the second micoservice expects a com.myApplication.api.commands.ApproveOrderCommand, that the first microservice shoots.

That solution may sound trivial to some, but since this is not described anywhere in the documentation and I didn't expect the name of the path to be relevant in handling the commands and events, you have to figure that out first.

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Original post:

I'm currently implementing a distributed command bus with spring cloud. I followed the below example exactly, but I'm getting the following issues in both of my (Client-)Microservices.

https://docs.axoniq.io/reference-guide/v/master/extensions/spring-cloud

1. Could not auto-wire. There is more than one Bean of "Registration" type.

Screenshot 1

2. Cannot find a bean with the qualifier "localSegment", even though I'm using Spring Auto Configuration.

Screenshot 2

I can start both the client-applications (this one and the other microservice) nevertheless.

But:

I can't send a command from the first Microservice to the second Microservice, the following error appears:

org.axonframework.commandhandling.NoHandlerForCommandException: No node known to accept [com.myApplication.PaymentManagementService.commands.CheckPaymentCommand]

Both microservices are registered to my eureka server.

In the first Microservice, I produce a command over a REST Endpoint, the Command fires outside of an Aggegrate (via commandGateway.send()).

In the second Microservice, I want to receive the command:

@Component
public class TestCommandHandler {

    @CommandHandler
    public void handle(ApproveOrderCommand command){
        System.out.println("Command delivered!");
    }

}

Is there anything wrong with my dependencies or application properties? Do I have to setup a saga for this to work?

One of my poms:

    <?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.myApplication</groupId>
    <artifactId>PaymentManagementService</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>PaymentManagementService</name>
    <description>Demo project for Spring Boot</description>
    
<properties>
    <java.version>11</java.version>
    <spring-cloud.version>Hoxton.SR9</spring-cloud.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-autoconfigure</artifactId>
        <version>2.3.5.RELEASE</version>
    </dependency>
    <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

    <!-- Axon -->
    <dependency>
        <groupId>org.axonframework</groupId>
        <artifactId>axon-spring-boot-starter</artifactId>
        <version>4.4.5</version>
        <!--
        <exclusions>
            <exclusion>
                <groupId>org.axonframework</groupId>
                <artifactId>axon-server-connector</artifactId>
            </exclusion>
        </exclusions>
        -->
        </dependency>

        <dependency>
            <groupId>org.axonframework</groupId>
            <artifactId>axon-spring-boot-autoconfigure</artifactId>
            <version>4.4.5</version>
        </dependency>

    <!-- Spring Cloud -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>
    <dependency>
        <groupId>org.axonframework.extensions.springcloud</groupId>
        <artifactId>axon-springcloud-spring-boot-starter</artifactId>
        <version>4.3.1</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter</artifactId>
        <version>2.2.6.RELEASE</version>
    </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

        <build>
            <plugins>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                </plugin>
            </plugins>
        </build>

    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
    </repositories>

    </project>

application.properties of Microservice 1

Properties_Microservice_1

application.properties of Microservice 2

Properties_Microservice_2

Answer 1

I'm glad that you found out the solution by yourself. Hope that you discovered our sample project https://github.com/AxonFramework/extension-springcloud-sample . This is a good starting point. It also contain some indication on dependency and version that your project should have. We also have the refguide that is a must read https://docs.axoniq.io/reference-guide/extensions/spring-cloud

Looking at your pom file is not clear to me if you are or you are not using axon server. If not, I can suggest to uncomment the exclusion of axon-server-connector dependency.