cowboy1.0¶

改变1.0->2.0:

2.0要求Erlang/OTP 19.0+
移除SPDY,支持HTTP/2
移除Hooks,使用stream handlers替代
Sub protocols仍然支持,但以后没有文档支持

handler behaviors有:cowboy_handler, cowboy_loop, cowboy_rest and cowboy_websocket
Plain HTTP, loop, REST and Websocket都有各自的init/2和terminate/3回调方法

cowboy:start_http/4   => cowboy:start_clear/3
cowboy:start_https/4  => cowboy:start_tls/3

websocket的handlers:

更新connection为Websocket protocol:
  init({tcp, http}, Req, Opts) ->
      {upgrade, protocol, cowboy_websocket}

% upgrade the handler to my_protocol
init(_Any, _Req, _Opts) ->
    {upgrade, protocol, my_protocol}.
upgrade(Req, Env, Handler, HandlerOpts) ->
% ...

% 方法
websocket_handle/3:
  receive data from the client
websocket_info/3:
  receive data from the server
websocket_terminate/3:
  websocket终止时
websocket_init/3:
  websockt开始时

websock实例:

-module(my_ws_handler).
-behavior(cowboy_websocket_handler).

-export([init/3]).
-export([websocket_handle/3, websocket_info/3]).
-export([websocket_init/3, websocket_terminate/3]).

init({tcp, http}, Req, Opts) ->
    {upgrade, protocol, cowboy_websocket}.

websocket_init(TransportName, Req, _Opts) ->
    erlang:start_timer(1000, self(), <<"hello">>,
    {ok, Req, undefined_state}.

websocket_handle({text, Msg}, Req, State) ->
    {reply, {text, <<"That's what she said!", Msg/binary>>}, Req, State};
websocket_handle(_Data, Req, State) ->
    {ok, Req, State}.

websocket_info({timeout, _Ref, Msg}, Req, State) ->
    erlang:start_timer(1000, self(), <<"How' you doin'?">>),
    {reply, {text, Msg}, Req, State};
websocket_info(_Info, Req, State) ->
    {ok, Req, State}.

websocket_terminate(_Reason, _Req, _State) ->
    ok.