使用cowboy和MessagePack在websocket上发送二进制数据

Question

我正在尝试通过WebSocket将来自Cowboy的MessagePack编码消息发送到浏览器,并且接收的数据始终为空或无效.我能够将JS中的二进制数据发送给我的牛仔处理程序,但反之亦然.我正在使用Cowboy 1.0.4和官方msgpack-erlang应用程序.我也msgpack-lite用于我的浏览器中的JavaScript.

例子:

websocket_handler:

websocket_handle({text, <<"return encoded">>}, Req, State) ->
    %% sends encoded message to client. Client is unable to decode and fails
    {reply, {binary, msgpack:pack(<<"message">>)}, Req, State};
websocket_handle({binary, Encoded}, Req, State) ->
    %% Works as expected
    lager:info("Received encoded message: ~p", [msgpack:unpack(Encoded)]),
    {ok, Req, State};

JS:

var host = "ws://" + window.location.host + "/websocket";
window.socket = new WebSocket(host);
socket.binaryType = 'arraybuffer';
socket.onmessage = function(event) {
    var message = msgpack.decode(event.data);
    console.log(message);
};

浏览器在msgpack.min.js中返回错误:

Error: Invalid type: undefined
...ion n(t){var r=i(t),e=f[r];if(!e)throw new Error("Invalid type: "+(r?"0x"+r.toSt...

如果我尝试将原始event.data输出到控制台,这是我得到的:

 ArrayBuffer {}

由于某种原因,它似乎是空的.我是新既erlang和msgpack,不知道什么错误.谢谢你的帮助!

Answer 1

找到了我的问题的原因.我尝试在客户端上解码消息的方式是错误的:

socket.onmessage = function(event) {
  var message = msgpack.decode(event.data);
  console.log(message);
};

正确的方式:

socket.onmessage = function(event) {
    var raw_binary_data = new Uint8Array(event.data);
    var message = msgpack.decode(raw_binary_data);
    console.log(message);
};