%% Copyright (c) 2011, Loïc Hoguin <essen@dev-extend.eu> %% %% Permission to use, copy, modify, and/or distribute this software for any %% purpose with or without fee is hereby granted, provided that the above %% copyright notice and this permission notice appear in all copies. %% %% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES %% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF %% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR %% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES %% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN %% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF %% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. %% @doc Handler for HTTP WebSocket requests. %% %% WebSocket handlers must implement four callbacks: <em>websocket_init/3</em>, %% <em>websocket_handle/3</em>, <em>websocket_info/3</em> and %% <em>websocket_terminate/3</em>. These callbacks will only be called if the %% connection is upgraded to WebSocket in the HTTP handler's <em>init/3</em> %% callback. They are then called in that order, although %% <em>websocket_handle/3</em> will be called for each packet received, %% and <em>websocket_info</em> for each message received. %% %% <em>websocket_init/3</em> is meant for initialization. It receives %% information about the transport and protocol used, along with the handler %% options from the dispatch list. You can define a request-wide state here. %% If you are going to want to compact the request, you should probably do it %% here. %% %% <em>websocket_handle/3</em> receives the data from the socket. It can reply %% something, do nothing or close the connection. %% %% <em>websocket_info/3</em> receives messages sent to the process. It has %% the same reply format as <em>websocket_handle/3</em> described above. Note %% that unlike in a <em>gen_server</em>, when <em>websocket_info/3</em> %% replies something, it is always to the socket, not to the process that %% originated the message. %% %% <em>websocket_terminate/3</em> is meant for cleaning up. It also receives %% the request and the state previously defined, along with a reason for %% termination. %% %% All of <em>websocket_init/3</em>, <em>websocket_handle/3</em> and %% <em>websocket_info/3</em> can decide to hibernate the process by adding %% an extra element to the returned tuple, containing the atom %% <em>hibernate</em>. Doing so helps save memory and improve CPU usage. -module(cowboy_http_websocket_handler). -export([behaviour_info/1]). %% @private -spec behaviour_info(_) -> undefined | [{websocket_handle, 3} | {websocket_info, 3} | {websocket_init, 3} | {websocket_terminate, 3}, ...]. behaviour_info(callbacks) -> [{websocket_init, 3}, {websocket_handle, 3}, {websocket_info, 3}, {websocket_terminate, 3}]; behaviour_info(_Other) -> undefined.