SWI-Prolog -- ws

Availability::- use_module(library(http/websocket)).

[det]ws_open(+Stream, -WSStream, +Options)

Turn a raw TCP/IP (or any other binary stream) into a websocket stream. Stream can be an input stream, output stream or a stream pair. Options includes

mode(+Mode): One of server or client. If client, messages are sent as masked.
buffer_size(+Count): Send partial messages for each Count bytes or when flushing the output. The default is to buffer the entire message before it is sent.
close_parent(+Boolean): If true (default), closing WSStream also closes Stream.
subprotocol(+Protocol): Set the subprotocol property of WsStream. This value can be retrieved using ws_property/2. Protocol is an atom. See also the subprotocols option of http_open_websocket/3 and http_upgrade_to_websocket/3.

A typical sequence to turn a pair of streams into a WebSocket is here:

    ...,
    Options = [mode(server), subprotocol(chat)],
    ws_open(Input, WsInput, Options),
    ws_open(Output, WsOutput, Options),
    stream_pair(WebSocket, WsInput, WsOutput).