event-sourced-system3

Event sourced system

Event sourcing aggregate is using a Decider from domain module to handle commands and produce new events. In order to handle the command, aggregate needs to fetch the current state via EventRepository.fetchEvents suspending function first. All you have to do is to implement this simple method.

New events will be stored via EventRepository.save suspending function. All you have to do, is to implement this simple method.

These two functions are producing side effects (persistence), and they are deliberately separated from the decider ( pure domain logic).

In this example we are using Axon Framework as a programming model and Axon Server as a message broker and event store database.

Axon Framework is constrained on the application and adapter/infra layers, enabling logic orchestration (aggregates), location transparency and message routing capabilities out of the box.

Running the application locally

Requirements

You can download a ZIP file with AxonServer as a standalone JAR. This will also give you the AxonServer CLI and information on how to run and configure the server.

Alternatively, you can run the following command to start AxonServer in a Docker container:

docker run -d --name axonserver -p 8024:8024 -p 8124:8124 axoniq/axonserver

mvn clean install
cd application/event-sourced-system3/
mvn spring-boot:run

References and further reading

• https://fraktalio.com/fmodel/

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