{"id":2608,"date":"2010-11-12T18:34:57","date_gmt":"2010-11-12T17:34:57","guid":{"rendered":"http:\/\/blog.jteam.nl\/2010\/11\/12\/tutorial-getting-started-with-cqrs-and-axon-framework\/"},"modified":"2010-11-12T18:34:57","modified_gmt":"2010-11-12T17:34:57","slug":"tutorial-getting-started-with-cqrs-and-axon-framework","status":"publish","type":"post","link":"https:\/\/trifork.nl\/blog\/tutorial-getting-started-with-cqrs-and-axon-framework\/","title":{"rendered":"Tutorial – Getting started with CQRS and Axon Framework"},"content":{"rendered":"

Axon Framework<\/a> greatly simplifies building CQRS based Event Driven architectures in Java. Such an architecture provides very powerful options in terms of application scalability and extensibility. In this tutorial, I want to go though the process of setting up a basic application architecture with the Axon Framework.<\/p>\n

Building a foundation for your application can be divided in roughly four steps. First, we need to set up the project infrastructure. Which modules to we need? Which dependencies? The second step is to define the core API. What do we want our application to do? How can we tell it to do those things? This is when the definition of the commands and events is made. Building the command handling component, the one that consumes commands and produces events, is the third step. Lastly, in step four, the query component is build that turns events into a queryable data source for your application\u2019s client.<\/p>\n

Although this tutorial explains the process in a serial fashion, once you have done step 2, the definition of the core API, one team could work on the command handling component, while another team works on the query component.<\/p>\n

In this tutorial, I will focus on the backend development. There is nothing special going on in the UI, other than that it will need to send commands and call a \u201cservice layer\u201d to execute queries.<\/p>\n

If you\u2019re getting stuck somewhere, or just want to take the easy route through this tutorial, you can download the sources at: http:\/\/axonframework.googlecode.com\/files\/axon_tutorial.zip<\/a><\/p>\n

Step 1 \u2013 Project infrastructure<\/h2>\n

Before we can get started, we need to set up a basic project infrastructure. You can do this in any IDE and using any dependency management system you like to use, albeit maven, ant or just plain manual labor.<\/p>\n

To keep things, simple, we can use a single java source directory (src\/main\/java when using Maven). Inside we\u2019ll create a few packages that make it clear in which \u201cmodule\u201d we are working. In a real project, you\u2019d probably want to separate these packages over multiple modules\/jar files.<\/p>\n

Let\u2019s assume we are building an order management system for the Acme company. You need the following packages to get started:<\/p>\n