Events

The API exposes events for server lifecycle, connection state changes, and player tracking. Some of this is proxy-only. Each section notes which platforms support it.

Server lifecycle events

Proxy-only. Both methods return Optional.empty() on backends.

onServerConnected fires when a backend completes authentication. onServerDisconnected fires when a session is removed, either from a clean disconnect or a lost connection.

private final List<Subscription> subs = new ArrayList<>();

@Subscribe(order = PostOrder.LATE)
public void onProxyInitialize(ProxyInitializeEvent event) {
    api.onServerConnected(server -> {
        getLogger().info(server.id() + " joined the network");
    }).ifPresent(subs::add);

    api.onServerDisconnected(server -> {
        getLogger().info(server.id() + " left the network");
    }).ifPresent(subs::add);
}

@Subscribe
public void onProxyShutdown(ProxyShutdownEvent event) {
    subs.forEach(Subscription::cancel);
    subs.clear();
}

The ServerTarget passed to each listener has .id() (the server's configured identifier) and .type() (Platform.BACKEND or Platform.VELOCITY).

.ifPresent(subs::add) works on both platforms without any platform checks. On Velocity you get a Subscription, on backends you get an empty Optional and nothing happens. These methods are proxy-only, so in practice they only register on Velocity.

Connection state

onConnectionStateChanged is available on all platforms. The listener is called on every state transition.

private Subscription connectionListener;

@Subscribe(order = PostOrder.LATE)
public void onProxyInitialize(ProxyInitializeEvent event) {
    connectionListener = api.onConnectionStateChanged(state -> {
        if (state == ConnectionState.AUTHENTICATED) {
            getLogger().info("Bridge ready");
        } else if (state == ConnectionState.AUTH_FAILED) {
            getLogger().severe("Bridge auth failed. Check your secret key.");
        }
    });
}

@Subscribe
public void onProxyShutdown(ProxyShutdownEvent event) {
    connectionListener.cancel();
}

private Subscription connectionListener;

@Override
public void onEnable() {
    connectionListener = api.onConnectionStateChanged(state -> {
        if (state == ConnectionState.AUTHENTICATED) {
            getLogger().info("Bridge ready");
        } else if (state == ConnectionState.AUTH_FAILED) {
            getLogger().severe("Bridge auth failed. Check your secret key.");
        }
    });
}

@Override
public void onDisable() {
    connectionListener.cancel();
}

You can also query the current state directly at any time:

ConnectionState state = api.connectionState();
boolean ready = state.isActive();

isActive() returns true only when the state is AUTHENTICATED.

ConnectionState values:

State	Meaning
`DISCONNECTED`	No connection. Initial state.
`CONNECTING`	Socket is being established.
`CONNECTED`	Socket is open, authentication not yet complete. Messages cannot be sent.
`AUTHENTICATED`	Fully connected. `isActive()` returns `true`.
`RECONNECTING`	Connection dropped unexpectedly. Reconnect in progress.
`AUTH_FAILED`	Authentication failed. No further attempts will be made.

Platform differences:

On Velocity, connectionState() always returns AUTHENTICATED. onConnectionStateChanged fires immediately with AUTHENTICATED and returns a no-op Subscription. Canceling it does nothing.

On backends, the state reflects the actual client connection to the proxy. When you call onConnectionStateChanged, a background daemon thread starts polling every 500ms. Listeners are called on transitions.

If you see AUTH_FAILED on a backend, check that secret in the backend's config.yml matches the secret.key file on Velocity.

Player locator

Proxy-only. Returns Optional.empty() on backends.

playerLocator() returns a service for finding which server a player is currently on.

api.playerLocator().ifPresent(locator -> {
    Optional<Platform.ServerTarget> location = locator.locate(playerUUID);
    location.ifPresent(server -> {
        getLogger().info("Player is on " + server.id());
    });
});

locate(UUID) returns empty if the player is offline or not tracked by any authenticated session.

Connected servers

Proxy-only. Returns Optional.empty() on backends.

connectedServers() returns a snapshot of all server IDs that are currently connected and authenticated:

api.connectedServers().ifPresent(servers -> {
    getLogger().info("Connected: " + String.join(", ", servers));
});

This is a point-in-time snapshot. Use onServerConnected and onServerDisconnected to track changes in real time instead.

Server identity

Available on all platforms. api.server() returns a ServerTarget with the current server's own configured ID and platform type:

Platform.ServerTarget me = api.server();
getLogger().info(me.id() + " on " + me.type());

On Velocity, server() returns Platform.VELOCITY.target(serverId) where serverId is the server-id from config.yml. On backends, it returns Platform.BACKEND.target(clientId) where clientId is the client-id from config.yml.

Event methods

Optional<Subscription> onServerConnected(ServerEventListener listener)
Optional<Subscription> onServerDisconnected(ServerEventListener listener)

Subscription onConnectionStateChanged(Consumer<ConnectionState> listener)

ConnectionState connectionState()

Returns the current connection state. Always AUTHENTICATED on Velocity. Reflects the actual connection state on backends.

Optional<PlayerLocator> playerLocator()

Returns a player location service. Proxy-only. Returns Optional.empty() on backends.

Optional<Set<String>> connectedServers()

Returns a snapshot of connected and authenticated server IDs. Proxy-only. Returns Optional.empty() on backends.

Platform.ServerTarget server()

Returns the current server's own identity. Available on all platforms.