First module

This guide walks you through creating your first PME module.

1. Use the template

Go to pme-module-template and click "Use this template". Rename the repo to pme-module-{your-name}.

The template already contains the mandatory structure, pom.xml and module.yml.

2. Edit module.yml

Open src/main/resources/module.yml and fill in your module's info:

name: my-module
version: 1.0.0
author: my-name
description: My module description
priority: MEDIUM
subscribes-to:
  - TRANSACTION

3. Edit the code

Rename the package and class to match your module, then implement your logic in onEvent():

public class MyModule implements EventModule {

    @Override
    public ModuleConfig config() {
        return ModuleConfigReader.load();
    }

    @Override
    public void onEvent(Event event, EventContext context) {
        double amount = (double) event.payload().get("amount");

        if (amount > 5000) {
            context.log("High transaction detected: {} EUR", amount);
        }
    }
}

ModuleConfigReader.load() reads this file and builds the ModuleConfig automatically.

Field	Type	Required	Description
name	string	Yes	Unique module identifier
version	string	Yes	Module version (e.g. 1.0.0)
author	string	Yes	Author or organization
description	string	Yes	Short module description
priority	string	Yes	LOW, MEDIUM, HIGH or CRITICAL
subscribes-to	list	Yes	Event types to listen to

Validation

A missing or empty field causes a startup error. The core refuses to load the module.

Listen to multiple event types

Set.of(EventType.TRANSACTION, EventType.USER_ACTION, EventType.SYSTEM_LOG)

Listen to all types

Set.of(EventType.values())

4. Using the context

The EventContext is provided by the core on each onEvent() call. It allows you to:

@Override
public void onEvent(Event event, EventContext context) {
    // Log a message
    context.log("Processing event {}", event.uuid());

    // Re-publish an event (chaining)
    Event alert = new Event(
        UUID.randomUUID(),
        EventType.NOTIFICATION,
        "my-module",
        Map.of("alert", "threshold exceeded"),
        Instant.now(),
        Priority.HIGH
    );
    context.publish(alert);
}

5. Lifecycle (optional)

Implement ModuleLifecycle to react to startup, shutdown, or errors:

public class MyModule implements EventModule, ModuleLifecycle {

    @Override
    public void onStart() {
        // Called when the module is loaded
    }

    @Override
    public void onStop() {
        // Called when the core shuts down
    }

    @Override
    public void onError(Event event, Exception exception) {
        // Called when onEvent() throws an exception
    }

    // ... config() and onEvent()
}

All three methods are default — only implement the ones you need.

6. Deploy

Compile your module as a jar and place it on the core's classpath. The ModuleLoader automatically detects it at startup.