civetweb/docs/api/mg_websocket_write.md

Civetweb API Reference

mg_websocket_write( conn, opcode, data, data_len );

Parameters

Parameter	Type	Description
conn	struct mg_connection *	Connection on which the data must be written
opcode	int	Opcode
data	const char *	Data to be written to the client
data_len	size_t	Length of the data

Return Value

Type	Description
int	Number of bytes written or an error code

Description

The function mg_websocket_write() sends data to a websocket client wrapped in a websocket frame. The function issues calls to mg_lock_connection() and mg_unlock_connection() to ensure that the transmission is not interrupted. Data corruption can otherwise happen if the application is proactively communicating and responding to a request simultaneously.

The function is available only when Civetweb is compiled with the -DUSE_WEBSOCKET option.

The function returns the number of bytes written, 0 when the connection has been closed and -1 if an error occurred.

See Also

• mg_lock_connection();
• mg_printf();
• mg_unlock_connection();
• mg_websocket_client_write();
• mg_write();