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

AndroidTuts

2 years ago

fmodel-spring-demo (EventSourcing)

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

this bleuprint is an outcome of the event-modeling process

Fmodel

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
}

Fstore-SQL

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

Tools

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

Patterns

EventSourcing
CQRS

Prerequisites

Technology

Fmodel – Domain modeling with Kotlin
Kotlin (Coroutines, Serialization)
Spring (Reactive Web,R2DBC, RSocket)
Testcontainers
PostgreSQL (event store, projections)

Run & Test

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

Test:

./gradlew check

Run:

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

./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

GitHub

View Github