By Christian Findlay 25 Jul 2026

WebSockets

Runtime surface [BUILTIN-WEBSOCKET]

The native runtime exposes a text-frame WebSocket transport. Handles and operation results are int; negative values report failure.

Client

websocketConnect(url: string) -> int
websocketSend(wsID: int, message: string) -> int
websocketClose(wsID: int) -> int

websocketConnect accepts a ws:// URL and returns a connection handle. websocketSend returns 0 on success. The language surface does not expose a receive callback or incoming-frame iterator.

Server

websocketCreateServer(port: int, address: string, path: string) -> int
websocketServerListen(serverID: int) -> int
websocketServerBroadcast(serverID: int, message: string) -> int
websocketKeepAlive() -> Unit

The server accepts upgrade requests, sends a welcome text frame, and echoes received text payloads. websocketServerBroadcast returns the number of connections written. websocketKeepAlive blocks until SIGINT or SIGTERM. The path argument is stored with the server but is not used to filter upgrade requests.

Framing limits

The runtime handles single text frames only. It does not implement fragmented, binary, close, ping, or pong frames, and outbound payloads are limited to 4096 bytes. Client frames are not masked, and the client transport rejects wss://.