An example application to test out some JVM-related tecnologies
Instructions • Tech Stack • Getting started • Accessing the application • Design considerations
Instructions for the challenge
SEAT:CODE has been asked for a really important project. We need to develop an application that helps in controlling brand new mowers from the SEAT Martorell Factory.
SEAT Martorell factory has a lot of green spaces but for the MVP, we will consider only one single green grass plateau to simply the problem.
A green grass plateau, which is curiously rectangular, must be navigated by the mowers.
A mower’s position and location are represented by a combination of X and Y coordinates and a letter representing one of the four cardinal compass points (N, E, S, W). The plateau is divided up into a grid to simplify navigation. An example position might be 0, 0, N, which means the mower is in the bottom left corner and facing North.
In order to control a mower, SEAT Maintenance Office sends a simple string of letters. The possible letters are “L”, “R” and ”M”. “L” and “R” make the mower spin 90 degrees left or right respectively, without moving from its current spot. “M” means to move forward one grid point and maintain the same Heading. Assume that the square directly North from (X, Y) is (X, Y + 1).
The first line of input is the upper-right coordinates of the plateau, the bottom-left coordinates are assumed to be 0, 0. The rest of the input is information pertaining to the mowers that have been deployed.
Each mower has two lines of input. The first line gives the mower’s position, and the second line is a series of instructions telling the mower how to explore the plateau.
The position is made up of two integers and a letter separated by spaces, corresponding to the X and Y coordinates and the mower’s orientation. Each mower will be finished sequentially, which means that the second mower won’t start to move until the first one has finished moving.
The output for each mower should be its final coordinates and heading.
Input Test Case #1:
5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM
Output Test Case #2:
1 3 N
5 1 E
- Runtime 👉 JRE 17.0.5
- Language 👉 Kotlin 1.8.0
- Delivery Mechanism 👉 Spring Boot 2.7.7
- Database 👉 MySQL 8.0.31
This repository supports two ways to run the application: locally or fully dockerized. Anyway this is what you should do to get started 👇
git clone https://github.com/theUniC/seat-mowers-kata.git
cd seat-mowers-kata
For this SDKMan comes in very handy
sdk env
docker compose up -d
This application uses dotenv files to handle the environment-depedent configuration.
cp .env.example .env
./gradlew flywayMigrate -i
./gradlew build bootRun
./gradlew test
To run the application fully dockerized you only need to have Docker installed
docker compose up -d
Wait a few seconds until MySQL is ready and then
docker compose run --profile db-migrations run flyway
The application container is defined in the docker-compose.override.yaml.dist so you will need to copy it with a new file name of docker-compose.override.yaml
cp docker-compose.override.yaml.dist docker-compose.override.yaml
And then start services up again
docker-compose up -d
The application has several endpoints of interest
- Web frontend
- REST and OpenAPI
- GraphQL
The application has a web frontend made specifically to run instructions in the from described in the instructions section. It can be accessed at
http://127.0.0.1:8080/api/instructions
Additionally executions are saved to later check them again at
http://127.0.0.1:8080/api/executions
To access the REST API there is a swagger UI endpoint at
http://127.0.0.1:8080/api/swagger-ui/index.html
And the OpenAPI document can be accessed
http://127.0.0.1:8080/api/v3/api-docs
Additionally an exported Postman collection is provided here.
The application also supports GraphQL in this endpoint
http://127.0.0.1:8080/api/graphql
And can be queried using GraphiQL at this URL
http://127.0.0.1:8080/api/graphiql
- This application uses Tactical DDD to better implement the Ubiquitous Language defined at the instructions section.
- As application architecture it is using Event Sourcing + CQRS, as it's using Axon Framework to handle domain messages and the default mode of this framework is Event Sourcing.
- When a mower tries to move to an occupied position, then an exception is thrown. It can be changed to do nothing pretty easily.
- There's just a single Aggregate – Plateau – which receives all the Commands. That is it acts both as an Aggregate and as a Command Handler. This has been done that way because we need inmediate consistency between both Plateau and deployed mowers.