crabzilla

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https://www.oracle.com/java/[image:https://img.shields.io/badge/Java-17-purple.svg[Vertx]] https://kotlinlang.org/[image:https://img.shields.io/badge/Kotlin-1.9.22-purple.svg[Vertx]] https://vertx.io[image:https://img.shields.io/badge/vert.x-4.5.1-purple.svg[Vertx]] https://github.com/crabzilla/crabzilla/actions/workflows/blank.yml[image:https://github.com/crabzilla/crabzilla/actions/workflows/blank.yml/badge.svg[CI]] https://codecov.io/gh/crabzilla/crabzilla[image:https://codecov.io/gh/crabzilla/crabzilla/branch/main/graph/badge.svg[codecov]] https://jitpack.io/#io.github.crabzilla/crabzilla[image:https://jitpack.io/v/io.github.crabzilla/crabzilla.svg[Jitpack]]

== Objectives

. Allows writing your testable CQRS/ES model with minimal dependencies. . Allows consistently handling your commands and save resulting events into Postgres. . Allows consistently and ordered projecting your events to your view models in Postgres. . Allows consistently and ordered publishing your events to Vertx eventbus, so you can integrate with any message broker, database, cache, etc.

== Approach

• Using https://vertx.io/docs/vertx-pg-client/java/[Vertx] non-blocking IO Postgres driver.
• Using key Postgres features: json, notification and advisory locks.
• Trying to be idiomatic Kotlin: type safeness: immutability, pattern matching, honouring your constructors.

== crabzilla-core

To express your domain model.

• State transitions occurs after computing results of pure functions (State, Event) -> State.
• Tests in BDD way without any dependency to Vertx: only to crabzilla-core:
  ** given command, then assertion
  ** given events, when command, then assertion
  ** given commands or events in any order, then assertion

== WIP