How to write an Axon application?

By Frans van Buul

Learning to write a proper Axon application from scratch consists of various aspects. However, talking with AxonIQ customers, I found out that there's something we may need to be a little more clear about: What does the general structure of a real-life Axon application look like? What goes where, and how do you prevent a mess? In this blog, I'll try to shed some light on this topic.

Some CQRS and Event Sourcing Pitfalls

By Frans van Buul

In one of our recent blogs, we talked about constructing a real-life Axon application. Which areas should you distinguish on a high level, and what code should go where? Which pitfalls are there that we should avoid?  I will cover some of these in this blog. It’s based on stuff I’ve seen happening for real when working with many Axon clients.

Parameter Resolvers in Axon

By Milan Savić

Axon is an open-source Java framework for building systems in CQRS (Command Query Responsibility Separation), DDD (Domain Driven Design), and Event Sourcing. Axon Framework is message-based - commands, events, and queries are supported types of messages. Axon provides a potent mechanism to inject these dependencies into message handlers - Parameter Resolvers. This is the story about them. At the end of this article, you can find a cheat sheet of all resolvers provided by the Axon Framework.

CQRS replay performance tuning

By Frans van Buul

CQRS has become a popular pattern to avoid complex, and therefore slow, database queries in applications. Axon offers a mature and popular implementation of the CQRS/ES concepts on the JVM, but several other implementations exist. CQRS/ES presents a solution to a common performance problem. On the other hand, it introduces a couple of new potential performance challenges.

Sagas in practice

By Yvonne Ceelie

This blog is a how-to implement a Saga with Axon and Spring Boot. Saga’s are a powerful concept but, you need to think about other options before implementing a Saga. You’ll have to keep in mind that the Saga should only orchestrate the process. If you conclude a Saga is the best option, this blog provides some good practices to help you get started.

Introducing The AxonIQ Initializr

By Ben Runchey

Sometimes the most challenging part of any project is getting started. Tasks such as creating the structure for various project artefacts, creating a build file, determining maven coordinates, and picking the right dependency versions can be boring and repetitive. But tragically, Axon Framework isn’t available in the Spring Initializr. So, at AxonIQ, we felt it was high time that we corrected this glaring oversight by providing our very own AxonIQ Initializr just for you, our loyal Axonians!

Demystifying repositories

By Milen Dyankov

Repositories are essential components in Axon Framework. However, they mostly remain behind the scenes, and developers don't need to interact with them directly. Usually, the framework can configure, instantiate and use the correct repository based on how the developer has constructed the domain components. That convenience sometimes leads to misunderstandings. Those are caused by the many meanings of the term "repository" and the assumptions developers make when they hear or read it.

Upgrading to Axon Framework 4.7

By Steven van Beelen

Different than usual, upgrading to Axon Framework 4.7.x may just impact your application.
For that, we want to extend our apologies, as this differs from our desired approach towards minor releases.
This blog describes several upgrade scenarios, like what you need to do when you want to move to Jakarta or stay on Javax.
Each scenario provides a list of actions to upgrade to 4.7 to guide you.