# Events and signals Communicate through queued global events and object-scoped signals across scripting languages. [Feature status and language/platform compatibility](https://rustic-game-engine.pages.dev/markdown/reference/compatibility.md) Choose an API to see its signature, parameters, examples and behavior. ## APIs - [Events.on()](https://rustic-game-engine.pages.dev/markdown/api/events/on.md) - [Events.once()](https://rustic-game-engine.pages.dev/markdown/api/events/once.md) - [Events.connect()](https://rustic-game-engine.pages.dev/markdown/api/events/connect.md) - [Events.emit()](https://rustic-game-engine.pages.dev/markdown/api/events/emit.md) - [connection.disconnect()](https://rustic-game-engine.pages.dev/markdown/api/events/connection-disconnect.md) - [Events.disconnect()](https://rustic-game-engine.pages.dev/markdown/api/events/disconnect.md) ## Module guide ## Setup and language support These engine-owned services work in Lua 5.4, Luau, JavaScript, Python, C, C++, C#, Java, PHP, and HTML inline JavaScript. Follow [Use gameplay actions](https://rustic-game-engine.pages.dev/markdown/guides/gameplay-actions.md) to create and attach a script, install external toolchains, and choose the correct language binding. PHP and HTML scripts belong under `ui/`; CSS alone runs no gameplay code. The Calls section uses JavaScript signatures. The function examples below include native syntax for all ten script types, including SDK-specific alternatives and limitations. Attach a JavaScript Object Component script to the specified target and press **Play**. Globals are supplied by the engine. Schedule actions from `Start` or a callback, rather than at script top level. Native languages use typed options and their own builder conventions; see the guide's language bindings. ## Parameters Name is the exact signal name. Callback receives payload arguments. Source is an optional stable entity ID or resolvable scene path. Payload supports booleans, finite numbers, strings/IDs, vectors and quaternions, not arbitrary nested objects. ## Return and timing On/once/connect return a connection with disconnect. Emit queues delivery during Update before the user frame callback; it never synchronously enters another language runtime. ## Behavior and limitations - The Console prints opened by followed by the owner ID on queued delivery. Once disconnects after its single delivery. - Global on/once subscriptions are distinct from object signals. For an object signal use connect(object, name, callback) and emit(name, args, object). - Language instances in the same play scene can communicate; no network or inter-scene transport is implied. - Payload limits are 64 arguments, 4096 bytes per string and 16 KiB combined. The scene retains at most 4096 subscriptions and 4096 callbacks per queue. - Destroying an object removes its scoped connections. Unrelated object destruction does not remove a global script subscription. - Check script attachment, enabled state and the Console when an operation fails. Asynchronous errors also appear in operation state. Callback exceptions disable the owner and clean up its actions. - Owner destruction, disable, successful reload or Stop cleans up owned actions and subscriptions. Failed reload retains the previous behavior's operations. See [Operation handles](https://rustic-game-engine.pages.dev/markdown/api/operation-handles.md) for controls and lifetime details.