Microservices Chess

In this project I built a backend composed by several microservices that work together to simulate a matchmaking service for chess games to which several clients can connect and create a Game Proposal. A different client can then accept the proposal and a Game between the two clients will be created.

Each of these entities are saved in the form of a stream of events in an EventStore DB. This means that not only the last state of an entity is maintained, but the entire history of events that changed it. An entity can then be recovered by instantiating a new entity and applying to it the entire sequence of events of the stream.

Every microservice has been developed in TDD (Test Driven Development) in isolated environments using Docker and Dev Containers and the building and testing of the project can be automated through Maven.

To try out the fully functional application, every microservice can be deployed in its own container using Docker Compose. See Build and Run.

Microservices

The LobbyService and GameService implement the command-side of the CQRS pattern.
The WebService acts as a simple gateway to which the clients connect.

Lobby service

The Lobby service is responsible of handling the creation, cancellation and acceptance of Game Proposals. Each of these events produce a change in the state of the Game Proposal and are thus saved in the EventStore.

The API of this service provides the following operations:

• createGameProposal()
• cancelGameProposal()
• acceptGameProposal()

The API is served using the Jakarta EE specification and Wildfly.

Game service

The Game service is responsible of handling the game between two players. The Game is also an entity which state is modified by events generated by the players which are thus saved in the EventStore.

The API of this service provides the following operations:

• createGame()
• playMove()

The API is served using the Jakarta EE specification and Wildfly.

Web service

The web service provides a WebSocket interface to which the clients connect and will in turn call the other services API.
It also uses the subscription feature of EventStore to listen for events of interest to send back to clients.

The API of this service provides the following operations:

• sendCreateGameProposalRequest()
• sendAcceptGameProposalRequest()
• sendPlayMoveRequest()

WebSocket is implemented using Spring Boot.

I also created a simple frontend to try out the application using Vue.js which is served by the Web service for simplicity.

Build and Run

Clone the repo:

$ git clone https://github.com/marcodiri/micros-chess.git
$ cd micros-chess

Testing

Unit tests:

$ mvn clean test -f "./micros-chess-parent/pom.xml"
# Or with Docker
$ docker run -it --rm -v "$(pwd)":/usr/src/mymaven -w /usr/src/mymaven maven:3.9.4-eclipse-temurin-17-alpine mvn clean test -f "./micros-chess-parent/pom.xml"

Integration tests (Docker required):

$ mvn clean verify -f "./micros-chess-parent/pom.xml"

Run

Run the script (Docker required):

$ chmod +x ./build-and-run.sh
$ ./build-and-run.sh

The script will automatically pull Node and Maven images to build the microservices and the Wildfly and EventStoreDB images to start the services.
You can then open the application in your browser by visiting http://localhost:8080.
The EventStore can be explored at http://localhost:2113.

Demo

preview.mp4