Modules
Axon Framework consists of a number of modules that provide specific capabilities. Depending on the exact needs of your project, you will need to include one or more of these modules.
There are currently two ways of obtaining the module binaries: either download the binaries from our website or preferably configure a repository for your build system (Maven, Gradle).
To not be bothered with version compatibility issues between framework and the extensions, it is recommended to use the BOM.
Axon modules are available on Maven Central.
Main modules
Axon 'Main Modules' are the modules that have been thoroughly tested and are robust enough to use in demanding production environments.
The maven groupId of all these modules is org.axonframework.
Visit Maven Central Repository to copy coordinates for the version you need.
Quick start an Axon Application
The Axon Spring Boot Starter extension is the quickest start in to an Axon project as it will retrieve all the required modules/dependencies transitively. See the Extension modules section below for details. Alternatively, you can manually select individual modules for a customized configuration.
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Axon common
This module contains all common components utilized by Axon Framework throughout. Examples of what is container are Axon’s caching integration, configuration implementation, application descriptors, and numerous utility classes.
Axon conversion
This module provides the conversion interfaces and implementations, used to (for example) convert every Message#payload when sending and receiving them.
Axon messaging
This module contains all necessary components and building blocks to support command, event, and query messaging.
Axon Event Sourcing
This module contains all necessary infrastructure components to support Event Sourcing, Command Models, and Query Models.
Axon test
This module contains test fixtures that you can use to test Axon based components, such as your command handlers and entities. You typically do not need this module at runtime and will only need to be added to the classpath for running tests.
Axon update
This module Axon Framework’s update checker, ensuring your Axon application is as up to date as possible. For more details on this component we refer to this section of our documentation.
Extension modules
Besides main modules, there are several extension modules which complement Axon Framework.
The maven groupId of these extensions starts with org.axonframework.extensions.*.
Visit Maven Central Repository to copy coordinates for the version you need.
Framework extensions
These extensions are part of the main Axon Framework repository and provide essential integration and monitoring capabilities.
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Axon Spring
This extension allows Axon Framework components to be configured in the Spring application context. It provides integration with Spring Framework, enabling bean-based registration and lifecycle management of Axon components.
Axon Spring Boot Starter
This extension provides Spring Boot auto-configuration for your project. It is by far the easiest option to get started as it automatically configures all Axon components. It is explained in more details here.
Dropwizard metrics
This extension provides basic implementations based on Dropwizard to collect monitoring information.
Micrometer metrics
This extension provides basic implementations based on Micrometer to collect monitoring information. Micrometer is a dimensional-first metrics collection facade whose aim is to allow you to time, count, and gauge your code with a vendor neutral API.
Axon Tracing OpenTelemetry
This extension contains the components needed to enable tracing with OpenTelemetry.
External extensions
These extensions are maintained in separate repositories and address distribution concerns of Axon Framework towards non-Axon Server solutions.
These extensions can be found under the group identifier io.axoniq.framework and are listed below:
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Axon PostgreSQL
This module provides a storage solution optimized for use with PostgreSQL by taking advantage of PostgreSQL-specifics. It supported the Dynamic-Consistency Boundary, just as Axon Server does
Axon Bill of Materials
In addition to the main framework modules and the extensions, Axon also has a Bill of Materials, or BOM. The BOM is provided to ensure the use of compatible framework and extension dependencies inside an Axon application. As such, it is the recommended approach towards defining the overall Axon version used inside of an application.
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For using the BOM, you would add the axon-bom dependency to your dependency management system:
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Maven
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Gradle
<!--...-->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.axonframework</groupId>
<artifactId>axon-framework-bom</artifactId>
<version>${version.axon}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
...
</dependencies>
</dependencyManagement>
<!--...-->For usage with Gradle Version 4.x and below, apply the dependency-management-plugin like so:
buildscript {
repositories {
jcenter()
}
dependencies {
classpath "io.spring.gradle:dependency-management-plugin:0.5.1.RELEASE"
}
}
apply plugin: "io.spring.dependency-management"After this, import the Axon BOM:
dependencyManagement {
imports {
mavenBom 'org.axonframework:axon-framework-bom:<VERSION>'
}
}Beginning with Gradle version 5.0, you can also omit the dependency-management plugin and instead use the platform dependency DSL to import maven BOMs:
implementation(platform("org.axonframework:axon-bom:<VERSION>"))
After that is in place, you can add any of the mentioned dependencies from framework and the extensions without specifying versions. Furthermore, you will be guaranteed that the provided versions in the BOM are compatible with one another.