几秒钟后，Firefox 附加组件断开与 Kodi 的 WebSocket 连接

Question

我决定为 Firefox 开发一个附加组件来控制 Kodi because I couldn't find any that already did everything I wanted. I have chosen to use WebSocket to communicate with Kodi so that I can receive events, but am having problems implementing the WebSocket portion of my add-on. Temporarily, I have created an add-on with a page-worker 仅用于测试 WebSocket 功能。我的开发插件和临时测试插件都表现出以下行为：

如果我直接在附加组件之外的 Firefox 中加载 test.html（有关内容，请参阅 post 的底部），WebSocket 会按预期工作。当我播放或暂停 Kodi 时，连接保持打开状态并接收事件：

控制台输出运行 test.html 在插件之外

Connection opened test.html:12:9
Object { jsonrpc: "2.0", method: "Player.OnPlay", params: Object } test.html:28:9
Object { jsonrpc: "2.0", method: "Player.OnPause", params: Object } test.html:28:9
Object { jsonrpc: "2.0", method: "Player.OnPlay", params: Object } test.html:28:9
Object { jsonrpc: "2.0", method: "Player.OnPause", params: Object } test.html:28:9
Object { jsonrpc: "2.0", method: "Player.OnPlay", params: Object } test.html:28:9
Object { jsonrpc: "2.0", method: "Player.OnPause", params: Object } test.html:28:9
Object { jsonrpc: "2.0", method: "GUI.OnScreensaverActivated", params: Object } test.html:28:9

但是，当运行从命令行使用 jpm run 加载项时，情况并非如此。连接在几秒后关闭（最多四秒）。（请注意，在连接打开期间我可以很好地接收事件）：

运行使用 jpm

的插件的控制台输出

C:\Users\User\Desktop\example>jpm run
JPM [info] Starting jpm run on test
JPM [info] Creating a new profile
console.log: test: Connection opened
console.log: test: {"jsonrpc":"2.0","method":"Player.OnPlay","params":{"data":{"item":{"id":23,"type":"song"},"player":{"playerid":0,"speed":1}},"sender":"xbmc"}}
console.log: test: {"jsonrpc":"2.0","method":"Player.OnPause","params":{"data":{"item":{"id":23,"type":"song"},"player":{"playerid":0,"speed":0}},"sender":"xbmc"}}
console.log: test: Websocket error: undefined
console.log: test: Connection closed: 1006

我如何找出为什么连接在插件内部断开，但在插件外部却没有？我该如何补救这种奇怪的行为？

index.js:

var data = require("sdk/self").data;
var pageWorker = require("sdk/page-worker");

var pw = pageWorker.Page({
  contentURL: data.url('test.html')
});

pw.port.on('message', function(message) {
  console.log(message);
});

test.html:

<!DOCTYPE html>
<html lang="en-US">
  <head>
  <meta http-equiv="content-type" content="text/html; charset=utf-8">
    <script type=text/javascript>
    var ws = new WebSocket('ws://192.168.2.34:9090/jsonrpc');

    ws.onopen = function (event) {
      try {
        addon.port.emit('message', "Connection opened");
      } catch (e) {
        console.log("Connection opened");
      }
    };

    ws.onerror = function (event) {
      try {
        addon.port.emit('message', "Websocket error: "+event.data);
      } catch (e) {
        console.log("Websocket error: "+event.data);
      }
    };

    ws.onmessage = function (event) {
      try {
        addon.port.emit('message', JSON.parse(event.data));
      } catch (e) {
        console.log(JSON.parse(event.data));
      }
    };

    ws.onclose = function (event) {
      try {
        addon.port.emit('message', "Connection closed: "+event.code);
      } catch (e) {
        console.log("Connection closed: "+event.code);
      }
    };
    </script>
  </head>
  <body>
  </body>
</html>

Answer 1

我安装了 Wireshark 并发现当运行在插件内部时发送了一个 Websocket ping 请求，但在插件外部没有。 Kodi 无法用 pong 响应 ping，因此 Firefox 关闭了连接。

有趣的是，加载项内的延迟连接和后续连接似乎没有生成 ping 请求，因此不会关闭。因此，解决方案是在连接关闭时简单地延迟或重新打开连接（无论如何这样做都可以处理网络连接丢失）。

test.html

<!DOCTYPE html>
<html lang="en-US">
  <head>
  <meta http-equiv="content-type" content="text/html; charset=utf-8">
    <script type=text/javascript>

    //connect(); //generates a ping request
    setTimeout(connect, 10000); //doesn't generate a ping request
    
    function connect() {
      this.ws = new WebSocket('ws://192.168.2.34:9090/jsonrpc');

      this.ws.onopen = function (event) {
        try {
          addon.port.emit('message', "Connection opened");
        } catch (e) {
          console.log("Connection opened");
        }
      };
      
      this.ws.onerror = function (event) {
        try {
          addon.port.emit('message', "Websocket error: "+event.data);
        } catch (e) {
          console.log("Websocket error: "+event.data);
        }
      };
      
      this.ws.onmessage = function (event) {
        try {
          addon.port.emit('message', JSON.parse(event.data));
        } catch (e) {
          console.log(JSON.parse(event.data));
        }
      };
      
      this.ws.onclose = function (event) {
        try {
          addon.port.emit('message', "Connection closed: "+event.code);
        } catch (e) {
          console.log("Connection closed: "+event.code);
        }
        setTimeout(connect, 5000); //re-opens connection, doesn't generate a ping request
      };
    }
    </script>
  </head>
  <body>
  </body>
</html>

几秒钟后，Firefox 附加组件断开与 Kodi 的 WebSocket 连接

Firefox add-on drops WebSocket connection to Kodi after a few seconds

javascript

firefox

firefox-addon

websocket

kodi

控制台输出运行 test.html 在插件之外

运行使用 jpm

index.js:

test.html:

test.html

几秒钟后，Firefox 附加组件断开与 Kodi 的 WebSocket 连接

Firefox add-on drops WebSocket connection to Kodi after a few seconds

javascript

firefox

firefox-addon

websocket

kodi

控制台输出 运行 test.html 在插件之外

运行 使用 jpm

index.js:

test.html:

test.html

控制台输出运行 test.html 在插件之外

运行使用 jpm