Reactor
Overlooking Axon Framework’s architecture, you can notice that in general systems using the framework are "Message Driven", "Responsive", "Resilient" and "Elastic". According to the Reactive Manifesto, the same holds for Reactive Systems in general.
Although we can state that Axon Framework is a type of reactive system, we can’t say that it is fully reactive.
| Reactive programming is an approach to writing software that embraces asynchronous I/O. Asynchronous I/O is a small idea that portends big changes for software. The idea is simple: alleviate inefficient resource utilization by reclaiming resources that would otherwise be idle, as they waited for I/O activity. Asynchronous I/O inverts the normal design I/O processing: the clients are notified of new data instead of asking for it, which frees the client to do other work while waiting for these notifications. |
By their nature, a reactive API and Axon are a great fit, as most of the framework’s operations are async and non-blocking. Providing a dedicated extension for this was thus a logical step to take. To that end, we chose to use Project Reactor to build this extension. Reactor builds on top of the Reactive Streams specification and is the de-facto standard for Java enterprise and Spring applications. As such, we feel it to be a great fit to provide an extension in, making Axon more reactive.
| Not all Axon components offer a reactive API, yet. The extension currently provides reactive gateways for commands, queries, and events, and a reactive variant of the dispatch interceptor. See Dispatching and Intercepting for the details. |
To use the Reactor Extension, add the axon-reactor artifact with group id org.axonframework.extensions.reactor to your project.
The artifact is versioned together with Axon Framework:
-
Maven
-
Gradle
<dependency>
<groupId>org.axonframework.extensions.reactor</groupId>
<artifactId>axon-reactor</artifactId>
<version>${axon.version}</version>
</dependency>implementation("org.axonframework.extensions.reactor:axon-reactor:$axonVersion")The reactive gateways are registered automatically when the artifact is on the classpath. In Spring Boot applications, no further configuration is required.