architecture.md

Architecture

Spring Boot application

+----------------+            +----------------+
|                |   Events   |                |
|    Javacord    | ---------> |   Listeners    |
|                | <--------- |                |
+----------------+  Messages  +----------------+
                                      ^
                                  DTOs|
                                      v
                              +----------------+
                              |                |
                              |    Services    |
                              |                |
                              +----------------+
                                      ^
                                Models|
                                      v
                              +----------------+            +----------------+
                              |                |  Entities  |                |
                              |  Repositories  | <--------> |    Database    |
                              |                |            |                |
                              +----------------+            +----------------+

Javacord

Javacord is a Java library for interacting with Discord servers. It receives events from Discord websocket, and passes them in a formalised format to listeners of corresponding type.

The event objects contain information that can be used for responding to the events on a Discord server. For instance, MessageCreatedEvent contains a TextChannel object, which in turn exposes the sendMessage() method to send a message to that channel.

Listeners

Handlers for events coming from Javacord. Each listener class implements some Listener interface directly, or indirectly, and is therefore picked up by Javacord which passes events down for processing. They parse/translate the information from text messages into POJOs (like parsing command-line arguments), which are then passed down to Services for further processing.

Services

They implement the logic behind games and transactions, and persist the results in the database via Repositories.

Repositories

Persistence layer for communicating with the database.

Database

Relational database for storing user credits, game outcomes, and other information. Each Discord user has a unique ID, therefore identifying users is trivial, and so is maintaining their state (e.g. credits balance).

Docker

                                +----------------------------+
                                |       Docker Network       |
                                |                            |
+----------------------+        |  +----------------------+  |
|                      |    JAR |  |                      |  |
|   Build Container    | -------+> |    Main Container    |  |
|                      |        |  |                      |  |
+----------------------+        |  +----------------------+  |
           ^                    |             ^              |
     Gradle|cache               |     Entities|              |
           v                    |             v              |
+----------------------+        |  +----------------------+  |
|                      |        |  |                      |  |
|  Build Cache Volume  |        |  |  Database Container  |  |
|                      |        |  |                      |  |
+----------------------+        |  +----------------------+  |
                                |                            |
                                +----------------------------+

Build container

Container for building and packaging the application.

Build cache volume

Volume for storing build cache. It speeds up each subsequent build, even if the build container has been destroyed.

Main container

Container for running the application. It's enclosed in a Docker network along with the database container.

Database container

Container running the relational database server.