Wslay is a WebSocket library written in C. It implements the protocol version 13
described in RFC 6455. This library offers 2 levels of API: event-based API and
frame-based low-level API. For event-based API, it is suitable for non-blocking
reactor pattern style. You can set callbacks in various events. For frame-based
API, you can send WebSocket frame directly. Wslay only supports data transfer
part of WebSocket protocol and does not perform opening handshake in HTTP.

Wslay supports:
* Text/Binary messages.
* Automatic ping reply.
* Callback interface.
* External event loop.

WWW: https://github.com/tatsuhiro-t/wslay