Creating plugins

warning

This feature is still work in progress. It may not be finished yet or may contain bugs.

This page will guide you through the development process of an example plugin for the Caesar system.

Prerequisites

• Java JDK 21 or newer
• IntelliJ IDEA (recommended)
• Maven (recommended)

Get started

First of all, you need to import the main API of Caesar into your project:

<repository>
  <id>unifiedvision-caesar</id>
  <name>Unified Vision Repo</name>
  <url>https://repo.codeblocksmc.de/caesar</url>
</repository>

maven {
    name "unifiedvisionCaesar"
    url "https://repo.codeblocksmc.de/caesar"
}

Dependency:

<dependency>
  <groupId>de.julianweinelt.caesar</groupId>
  <artifactId>CaesarMC</artifactId>
  <version>1.0-SNAPSHOT</version>
</dependency>

implementation "de.julianweinelt.caesar:CaesarMC:1.0-SNAPSHOT"

You have to let Caesar know that you want to register a plugin. Your plugin needs a main class that extends CPlugin. Example:

YourPlugin.java

public class YourPlugin extends CPlugin {
  @Getter
  private static YourPlugin instance;

  @Override
  public void onLoad() {
    instance = this; // Recommended at onLoad(). Afterwards, you can call YourPlugin.getInstance(); at runtime.
  }

  @Override
  public void onEnable() {
    // Code at enable startup goes here.
  }

  @Override
  public void onDisable() {
    // What should your plugin do when its being disabled?
  }

  @Override
  public void onBukkitEnable() {
    // Code at enable startup when loaded on CaesarBridge goes here.
  }
  
  @Override
  public void onBukkitDisable() {
    // Called when plugin is using CaesarBridge and is being disabled.
  }

  @Override
  public void onBukkitLoad() {
    // Called when plugin is loaded by CaesarBridge.
  }
}

You also need to give Caesar some information about your plugin, e.g. its name, its version, where main class is located in class path, who created the plugin, etc. Therefore, you have to create a file in your resources folder: plugin.json.

This JSON file defines the basic structure and metadata for integrating a plugin with the Caesar backend system. Below is a breakdown of all fields and their purposes.

note

All keys starting with "comment" (e.g. "comment", "comment1") are ignored during parsing. They serve as human-readable documentation inside the file.

🧩 plugin

This section contains general metadata about your plugin. These values are used for identification, dependency handling, and version control.

Key	Type	Description
name	string	The unique name of the plugin. This is required.
version	string	The version of the plugin (e.g. "1.0.0"). This is required.
authors	array of strings	List of authors or contributors to the plugin.
depend	array of strings	Optional. List of other plugins this plugin depends on. These must be loaded before this one.

⚙️ caesar

This section provides technical metadata needed for Caesar to load and run the plugin.

Key	Type	Description
mainClass	string	Fully qualified class name that acts as the plugin's main entry point (e.g., com.yourplugin.MainClass).
minAPIVersion	string	Minimum Caesar API version required to load this plugin. Prevents compatibility issues.
useBridge	boolean	If this plugin is compatible with CaesarBridge.

🖥️ client

This section defines how the plugin interacts with the Caesar Client, especially if it adds visual elements or pages.

Key	Type	Description
hasPage	boolean	Indicates whether this plugin includes a client-facing page.
pageViewPermission	string	The permission string required to view the plugin's page in the web interface.
default	boolean	If set to true, this page will be the default landing page for users who have access. Only one plugin should be marked as default.

📌 Example plugin.json

{
  "plugin": {
    "name:": "ExamplePlugin",
    "version": "1.0.0",
    "authors": ["You", "and", "others"],
    "depend": []
  },
  "caesar": {
    "mainClass": "com.yourplugin.MainClass",
    "minAPIVersion": "1.0.1",
    "useBridge": "true"
  },
  "client": {
    "hasPage": true,
    "pageViewPermission": "yourplugin.somepermission",
    "default": false
  }
}

note

When setting client.hasPage to true, you must create a page.json file.

🖇️ Using CaearBridge

Caesar uses the component CaesarBridge to connect to Minecraft servers. It's a plugin that must be installed on every server, if:

• The server is running stand-alone.
• You want to use report or punishment features.
• A plugin you've installed on the backend requires to be run on the Minecraft servers.