What if, when designing and coding new software, you could record all changes in the domain as a time series and return to them afterwards if necessary? With the Event Sourcing method, you can do it! In this article, we will go through the basics of the method and introduce a few easy-to-use tools to support it.

Traditionally, software has been used to be designed in such a way that a requirement specification is written, and based on this, software engineers design a data model and software. The challenge with this method is simply that the system only stores the current state, and the data from other systems, for example, cannot be used as a basis for construction, and it is not possible to know how the current state has been arrived at.  Event Sourcing offers an effective targeted remedy for this challenge.

How does the Event Sourcing method work and why is it especially good for Java developers?

The Event Sourcing method records all events that occur in the domain in the form of a time series. It enables many things. For example, consider a situation where you want to create a new service from business data. Since the Event Sourcing server has all the business-relevant events stored, it is easy to initialize the data of the new service. All previous events can be entered from the Event Sourcing server into the new service under construction.

Another advantage of Event Sourcing is the easier audit trail. When the Event Sourcing service records all changes in the domain in a time series, it is also easier to map and correct errors that have occurred on the way. In addition, it is easy for us to find out who did what and what.

There are various tools to support the implementation of the method, many of which are Java-based and therefore particularly suitable for the needs of Java developers. Event Sourcing is also well compatible with the Domain-Driven Design (DDD) method. The purpose of this method is to get people responsible for business and software development to speak the same language and thus enable the development of software that better serves the business needs. Learn more about the Domain-Driven Design method.

Although Event Sourcing is a method that has gained popularity among Java developers in particular, it is also well suited for use with other software languages. 

What kind of tools can be used to get started in Event Sourcing?

One of the market-leading and proven tools for Event Sourcing is the AxonIQ Framework. It is a java-based software library that makes it easy to implement the Event Sourcing architecture and saves its users from many time-consuming steps. With the help of the program library in question, it is possible to significantly speed up the development of the system. The AxonIQ Framework can be used in both microservices architecture and the more traditional systems based on monolithic architecture.

Axon Server, on the other hand, is a so-called Event store where events generated in Event Sourcing are stored. This comes ready-made alongside the AxonIQ Framework, saving its users the time and challenges spent on creating it as well. Axon Server also provides routing of messages that are essential in the event sourcing method between different services without configuration. Axon Server also enables agile scaling and growing of the system over time.

Do you want to learn more about Event Sourcing as a topic or related tools?

Miili Consulting and Dutch company AxonIQ collaborate In Finland, to help software development professionals use DDD, CQRS and Event Sourcing methods in software architecture and software development work. We are also happy to help you or your business get started smoothly with these methods. So feel free to contact us and let's talk more about the topic!