# crabzilla

**Repository Path**: github-codes/crabzilla

## Basic Information

- **Project Name**: crabzilla
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: Apache-2.0
- **Default Branch**: main
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2022-02-19
- **Last Updated**: 2022-03-11

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

:sourcedir: src/main/java
:source-highlighter: highlightjs
:highlightjsdir: highlight
:highlightjs-theme: rainbow
:revnumber: {project-version}
:example-caption!:
ifndef::imagesdir[:imagesdir: images]
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:toclevels: 4

https://vertx.io[image:https://img.shields.io/badge/vert.x-4.2.5-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://frontend.code-inspector.com/public/project/24241/crabzilla/dashboard[image:https://api.codiga.io/project/24241/score/svg[image]]
https://frontend.code-inspector.com/public/project/24241/crabzilla/dashboard[image:https://api.codiga.io/project/24241/status/svg[image]]
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 projecting events to your read models.

== Approach

* Using https://vertx.io/docs/vertx-pg-client/java/[Vertx] to implement a `non-blocking IO` event store.
* Idiomatic Kotlin: type safeness: pattern matching, honouring your constructors.
* Immutability: state transitions occurs after computing results of pure functions `(State, Event) -> State`.
* https://github.com/crabzilla/crabzilla/blob/main/crabzilla-pgclient/src/main/kotlin/io/github/crabzilla/pgclient/command/CommandController.kt[CommandController] is consistent by default: before handling a command, your state ID is pessimistically locked using https://www.postgresql.org/docs/14/explicit-locking.html#ADVISORY-LOCKS[Postgres Advisory Locks]
* https://github.com/crabzilla/crabzilla/blob/main/crabzilla-pgclient/src/main/kotlin/io/github/crabzilla/pgclient/projection/EventsProjectorVerticle.kt[EventsProjectorVerticle] allows handling your read model projection's strait from database: no need to publish your events to Kafka or NATS.
* You can use https://vertx.io/docs/#clustering[Vertx Clustering] to deploy your EventsProjectorVerticle instances. Projections with singleton clustered verticles (singleton writers) and also with High Availability built in Vertx :)
* JSON serialization using https://kotlinlang.org/docs/serialization.html[Kotlin serialization].

== Example application

https://github.com/rodolfodpk/accounts-z[Accounts]

== Status

Seems like it's finally reaching stable status :)

== More info

https://crabzilla.github.io/crabzilla/docs/index.html[Documentation]