fmodel-spring-demo (EventSourcing)

A demo/example project for the imaginary restaurant and order management.

event model image this bleuprint is an outcome of the event-modeling process


This project is using Fmodel – Kotlin, multiplatform library.

Fmodel is:

  • enabling functional, algebraic and reactive domain modeling with Kotlin programming language.
  • inspired by DDD, EventSourcing and Functional programming communities, yet implements these ideas and concepts in idiomatic Kotlin, which in turn makes our code

    • less error-prone,
    • easier to understand,
    • easier to test,
    • type-safe and
    • thread-safe.
  • enabling illustrating requirements using examples
    • the requirements are presented as scenarios.
    • a scenario is an example of the system’s behavior from the users’ perspective,
    • and they are specified using the Given-When-Then structure to create a testable/runnable specification
      • Given < some precondition(s) / events >
      • When < an action/trigger occurs / commands>
      • Then < some post condition / events >

Check the tests!

with(orderDecider) {
    givenEvents(listOf(orderCreatedEvent)) {         // PRE CONDITIONS
        whenCommand(createOrderCommand)              // ACTION
    } thenEvents listOf(orderRejectedEvent)          // POST CONDITIONS


This project is using PostgreSQL powered event store, optimized for event sourcing and event streaming.

Fstore-SQL is enabling event-sourcing and pool-based event-streaming patterns by using SQL (PostgreSQL) only.

  • event-sourcing data pattern (by using PostgreSQL database) to durably store events
    • Append events to the ordered, append-only log, using entity id/decider id as a key
    • Load all the events for a single entity/decider, in an ordered sequence, using the entity id/decider id as a key
    • Support optimistic locking/concurrency
  • event-streaming to concurrently coordinate read over a streams of events from multiple consumer instances
    • Support real-time concurrent consumers to project events into view/query models


  • EventModeling – a method of describing systems using an example of how information has changed within them over time.


  • EventSourcing
  • CQRS



Run & Test

This project is using Gradle as a build and automation tool.


./gradlew check


Make sure you have PostgreSQL installed and running. Check the connection URL and username/password in

./gradlew bootRun

Run in Docker

Make sure you have Docker installed and running.

Build OCI (docker) image:

./gradlew bootBuildImage

Run application and PostgreSQL:

docker-compose up

Further Reading

Excited to launch your next IT project with us? Let’s get started! Reach out to our team at [email protected] to begin the journey to success.


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