https://github.com/fraktalio/fmodel-ktor-demo
Fmodel demo - Functional and Algebraic Domain modeling - Ktor
https://github.com/fraktalio/fmodel-ktor-demo
cqrs-pattern event-modeling event-sourcing
Last synced: 5 months ago
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Fmodel demo - Functional and Algebraic Domain modeling - Ktor
- Host: GitHub
- URL: https://github.com/fraktalio/fmodel-ktor-demo
- Owner: fraktalio
- License: other
- Created: 2023-04-30T15:43:08.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2026-01-16T15:05:42.000Z (5 months ago)
- Last Synced: 2026-01-17T04:49:39.945Z (5 months ago)
- Topics: cqrs-pattern, event-modeling, event-sourcing
- Language: Kotlin
- Homepage:
- Size: 13.4 MB
- Stars: 20
- Watchers: 2
- Forks: 3
- Open Issues: 11
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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README
# fmodel-ktor-demo (EventSourcing)
A demo/example project for the imaginary restaurant and order management.
It is backing the [Fmodel Reference Guide](https://fraktalio.com/fmodel/).
It demonstrates how to run our unique domain and orchestrate it in an EventSourced/EventDriven way.
*this blueprint is an outcome of the [event-modeling](https://eventmodeling.org/posts/what-is-event-modeling/) process*
## Fmodel
This project is using [Fmodel](https://github.com/fraktalio/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!
```kotlin
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](https://github.com/fraktalio/fstore-sql), 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](https://eventmodeling.org/posts/what-is-event-modeling/) - a method of describing systems using an
example of how information has changed within them over time.
## Patterns
- EventSourcing
- CQRS
## Prerequisites
- [Java 17](https://adoptium.net/)
- [Docker](https://www.docker.com/products/docker-desktop/)
## Technology
- [Fmodel - Domain modeling with Kotlin](https://github.com/fraktalio/fmodel)
- [Ktor](https://ktor.io/) (HTTP)
- [Kotlin](https://kotlinlang.org/) (Coroutines, Serialization)
- [Arrow](https://arrow-kt.io/) (Fx Coroutines, ...)
- [Postgres](https://www.postgresql.org/) ([event store](https://github.com/fraktalio/fstore-sql), projections)
## Run & Test
This project is using [Gradle](https://docs.gradle.org) as a build and automation tool.
### Test:
```shell
./gradlew check
```
### Run:
> Make sure you have [Postgres](https://www.postgresql.org/download/) installed and running.
> Alternatively, you can use [Docker](https://www.docker.com/products/docker-desktop/) to run PostgreSQL.
```shell
docker run --name postgres -e POSTGRES_PASSWORD=postgres -p 5432:5432 -d postgres
```
> Check the connection URL in [application environment variables](src/main/kotlin/com/fraktalio/Env.kt)
```shell
./gradlew run
```
### Run in Docker
> Make sure you have [Docker](https://www.docker.com/products/docker-desktop/) installed and running.
Build OCI (docker) image:
```shell
./gradlew publishImageToLocalRegistry
```
Run application and Postgres database:
```shell
docker-compose up
```
## Further Reading
- Check the [FModel reference guide](https://github.com/fraktalio/fmodel)
- Read the [blog](https://fraktalio.com/blog/)
- Learn by example on the [playground](https://fraktalio.com/blog/playground)
- [Spring Boot version of this project](https://github.com/fraktalio/fmodel-spring-demo).
---
Created with :heart: by [Fraktalio](https://fraktalio.com/)
Excited to launch your next IT project with us? Let's get started! Reach out to our team at `info@fraktalio.com` to
begin the journey to success.