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ddd-cqrs-4-java-example

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Example Java DDD/CQRS/Event Sourcing microservices with Quarkus, Spring Boot and EventStore from Greg Young.

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- - maven.yml
- - maven-wrapper.jar
  - maven-wrapper.properties
- create-harry-osborn-command.json
- create-mary-jane-watson-command.json
- create-persons.sh
- create-peter-parker-command.json
- delete-harry-osborn-command.json
- delete-harry-osborn.sh
- cqrs-overview-small.png
- cqrs-overview.png
- - mvnw
  - mvnw.cmd
  - pom.xml
  - README.md
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  - README.md
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  - README.md
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- pom.xml
- README.md
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  - mvnw.cmd
  - pom.xml
  - README.md
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  - mvnw.cmd
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  - README.md
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  - mvnw.cmd
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  - README.md
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- README.md
.gitignore
docker-compose.yml
LICENSE.txt
mvnw
mvnw.cmd
pom.xml
quarkus.md
README.md
spring-boot.md

# Installation Guide

1. Get the code

git clone https://github.com/fuinorg/ddd-cqrs-4-java-example

Downloads the entire project code from GitHub to your computer.

cd ddd-cqrs-4-java-example

Moves into the project folder you just downloaded.

2. Docker

Easy Recommended

Prerequisites

Git Needed to download the project code from GitHub.
Docker Desktop Needed to build and run containers. Install it and keep it running in the background.

docker-compose up

Runs the command against the services defined in the compose file.

✅ Run docker compose ps to check the containers are Up. If the README mentions a port, open http://localhost:PORT in your browser.

Pulled directly from this repo's README.

3. Maven (Java)

Medium

Prerequisites

Git Needed to download the project code from GitHub.
JDK (Java) Required to build and run Java projects.
Maven The build tool used for the mvn command.

mvn clean install

Installs dependencies and builds the project using Maven.

✅ A BUILD SUCCESS message means it worked. The output is created under target/.

// repository documentation

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# ddd-cqrs-4-java-example
Example Java DDD/CQRS/Event Sourcing microservices with [Quarkus](https://quarkus.io/), [Spring Boot](https://spring.io/projects/spring-boot/) and the [EventStore](https://eventstore.org/) from Greg Young. The code uses the lightweight [ddd-4-java](https://github.com/fuinorg/ddd-4-java) and [cqrs-4-java](https://github.com/fuinorg/cqrs-4-java) libaries. No special framework is used except the well known JEE/Spring standards.

[![Java Development Kit 17](https://img.shields.io/badge/JDK-17-green.svg)](https://openjdk.java.net/projects/jdk/17/)
[![Apache](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://opensource.org/licenses/Apache-2.0)
[![Build Status](https://github.com/fuinorg/ddd-cqrs-4-java-example/actions/workflows/maven.yml/badge.svg)](https://github.com/fuinorg/ddd-cqrs-4-java-example/actions/workflows/maven.yml)

## Background
This application shows how to implement [DDD](https://en.wikipedia.org/wiki/Domain-driven_design), [CQRS](https://en.wikipedia.org/wiki/Command%E2%80%93query_separation) and [Event Sourcing](https://martinfowler.com/eaaDev/EventSourcing.html) without a DDD/CQRS framework. It uses just a few small libraries in addition to  standard web application frameworks like [Quarkus](https://quarkus.io/) and [Spring Boot](https://spring.io/projects/spring-boot/).

If you are new to the DDD/CQRS topic, you can use these mindmaps to find out more: 
- [DDD Mindmap](https://www.mindmeister.com/de/177813182/ddd)
- [CQRS Mindmap](https://www.mindmeister.com/de/177815383/cqrs)

Here is an overview of how such an application looks like:

[![Overview](https://raw.github.com/fuinorg/ddd-cqrs-4-java-example/master/doc/cqrs-overview-small.png)](https://raw.githubusercontent.com/fuinorg/ddd-cqrs-4-java-example/master/doc/cqrs-overview.png)

## Modules
- **Quarkus** - *Currently BROKEN* Two microservices (Command & Query) based on [Quarkus](https://quarkus.io/).
- **[Spring Boot](spring-boot)** - Two microservices (Command & Query) based on [Spring Boot](https://spring.io/projects/spring-boot/).

## Getting started
The following instructions are tested on Linux (Ubuntu 24)

**CAUTION:** Building and running on Windows will require some (small) changes.

### Prerequisites
Make sure you have the following tools installed/configured:
* [git](https://git-scm.com/) (VCS)
* [Docker CE](https://docs.docker.com/engine/installation/linux/docker-ce/ubuntu/)
* [Docker Compose](https://docs.docker.com/compose/)
* Hostname should be set in /etc/hosts (See [Find and Change Your Hostname in Ubuntu](https://helpdeskgeek.com/linux-tips/find-and-change-your-hostname-in-ubuntu/) for more information)

### Clone and install project 
1. Clone the git repository
   ```
   git clone https://github.com/fuinorg/ddd-cqrs-4-java-example.git
   ```
2. Change into the project's directory and run a Maven build
   ```
   cd ddd-cqrs-4-java-example
   ./mvnw install
   ```
   Be patient - This may take a while (~5 minutes) as all dependencies and some Docker images must be downloaded and also some integration tests will be executed.
   
### Start Event Store and Maria DB (Console window 1)
Change into the project's directory and run Docker Compose
```
cd ddd-cqrs-4-java-example
docker-compose up
```

### Start command / query implementations
Start one query service and then one command service.
You can mix Quarkus & Spring Boot if you want to!
* Quarkus *currently broken*
* [Spring Boot](spring-boot.md)

### Verify projection and query data
1. Open http://localhost:2113/ to access the event store UI (User: admin / Password: changeit)
   You should see a projection named "qry-person-stream" when you click on "Projections" in the top menu.
2. Opening http://localhost:8080/persons should show an empty JSON array
3. Opening http://localhost:8080/statistics should show an empty JSON array

### Execute some create commands (Console window 4)
Change into the demo directory and execute the command using cURL (See [shell script](demo/create-persons.sh) and JSON files with commands in [demo](demo)) 
```
cd ddd-cqrs-4-java-example/demo
./create-persons.sh
```   
Command service (Console window 3) should show something like
```
Update aggregate: id=PERSON 954177c4-aeb7-4d1e-b6d7-3e02fe9432cb, version=-1, nextVersion=0
Update aggregate: id=PERSON 568df38c-fdc3-4f60-81aa-d3cce9ebfd7b, version=-1, nextVersion=0
Update aggregate: id=PERSON 84565d62-115e-4502-b7c9-38ad69c64b05, version=-1, nextVersion=0
```   
Query service (Console window 2) should show something like
```
Handle PersonCreatedEvent: Person 'Harry Osborn' (954177c4-aeb7-4d1e-b6d7-3e02fe9432cb) was created
Handle PersonCreatedEvent: Person 'Mary Jane Watson' (568df38c-fdc3-4f60-81aa-d3cce9ebfd7b) was created
Handle PersonCreatedEvent: Person 'Peter Parker' (84565d62-115e-4502-b7c9-38ad69c64b05) was created
```

### Verify the query data was updated
1. Refreshing http://localhost:8080/persons should show
    ```json
    [
       {
           "id": "568df38c-fdc3-4f60-81aa-d3cce9ebfd7b",
           "name": "Mary Jane Watson"
       },
       {
           "id": "84565d62-115e-4502-b7c9-38ad69c64b05",
           "name": "Peter Parker"
       },
       {
           "id": "954177c4-aeb7-4d1e-b6d7-3e02fe9432cb",
           "name": "Harry Osborn"
       }
    ]
    ```
2. Opening http://localhost:8080/persons/84565d62-115e-4502-b7c9-38ad69c64b05 should show
    ```json
    {"id":"84565d62-115e-4502-b7c9-38ad69c64b05","name":"Peter Parker"}
   ```
3. Opening http://localhost:8080/statistics should show
   ```json
   [ { "type": "person", "count": 3 }  ]
   ```
4. The event sourced data of the person aggregate could be found in a stream named [PERSON-84565d62-115e-4502-b7c9-38ad69c64b05](http://localhost:2113/web/index.html#/streams/PERSON-84565d62-115e-4502-b7c9-38ad69c64b05)

### Execute a delete command (Console window 4)
Change into the demo directory and execute the command using cURL (See [shell script](demo/create-persons.sh) and JSON files with commands in [demo](demo))
```
cd ddd-cqrs-4-java-example/demo
./delete-harry-osborn.sh
```   
### Verify the query data was updated
1. Refreshing http://localhost:8080/persons should show
    ```json
    [
       {
           "id": "568df38c-fdc3-4f60-81aa-d3cce9ebfd7b",
           "name": "Mary Jane Watson"
       },
       {
           "id": "84565d62-115e-4502-b7c9-38ad69c64b05",
           "name": "Peter Parker"
       }
    ]
    ```
    "Harry Osborn" should no longer be present in the list.
2. Opening http://localhost:8080/statistics should show
   ```json
   [ { "type": "person", "count": 2 }  ]
   ```

### Stop Event Store and Maria DB and clean up
1. Stop Docker Compose (Ubuntu shortcut = ctrl c)
2. Remove Docker Compose container
   ```   
   docker-compose rm
   ```