• https://github.com/edwinans/smessenger

1. Register: Users can create an account with a unique username and password.
2. Login: Users can authenticate with username and password and receive a JWT authentication token.
3. Send message: Authenticated users can send a single message to another user.
4. Retrieve recent messages: Get recent messages from a specific sender, with pagination:

• Limit the number of returned messages
• Fetch messages before a specified message

• Tested on: Ubuntu 24.04
• Required
  • Java 25 (JDK). Verify: java -version
  • Docker and docker-compose
• Optional
  • Makefile

1. Start the PostgresSQL database:

   docker compose up -d

   Verify: docker compose ps
2. Build and run with the Maven Wrapper:

   ./mvnw spring-boot:run

   Or build a runnable jar:

   ./mvnw package java -jar target/smessenger.jar

   To build the package from scratch: ./mvnw clean install
3. Stop the database:

   docker compose down

Convenience: all of the above commands are also available via make (see Makefile). Common targets:

• make pg_up: start PostgreSQL container
• make pg_down: stop PostgreSQL container
• make run: run app in prod profile
• make dev: run app in dev profile
• make package and make run_jar: produce and run smessenger.jar

If you want to run the application using an in-memory H2 database for local development, start the app with the dev Spring profile. This will load application-dev.properties which configures H2.

./mvnw spring-boot:run -Dspring-boot.run.profiles=dev

The H2 web console is enabled in the dev profile at:

http://localhost:8080/h2-console

• JDBC URL: jdbc:h2:mem:testdb

• Username: sa

• Password: (leave blank)

• Notes

  • If you prefer system Maven, replace ./mvnw with mvn.
  • Application listens on localhost port 8080 by default
  • Ensure the database container is healthy before starting the app (check docker logs or docker compose ps).

• http://localhost:8080/swagger-ui/index.html
  • Login, retrieve jwt token and enter it in the global "Authorize" field (top-right)
• Postman collection
• Two test users are preloaded in the database: user1 and user2 (password: pass). Sample messages from user2 to user1 are included. Use these accounts to start testing.

flowchart TD A["Client"] <--> F["DTO (Data transfer objects)"] F <--> B["Controller (HTTP req/resp)"] B --> C["Service (Business logic)"] C --> D["Repository (Data access)"] D --> E["Model (Core business objects)"] D --> DB["Database server"]