web socket 入门

WebSocket是HTML5开始提供的一种在单个 TCP 连接上进行全双工通讯的协议，其优雅地解决了以往web服务器不能向web客户端实时推送消息的问题。

在浏览器js环境中，创建一个websocket对象如下所示:

var ws = New WebSocket(url, [protocol])

 第一个参数 url, 指定连接的 URL,一般web服务器会对这个url进行特殊的处理，一般会用实现了websocket协议的handler处理websocket请求。

第二个参数 protocol 是可选的，指定了可接受的子协议。

WebSocket事件

websocket提供了四个回调函数，分别用来处理open，close，message，error四个事件，即ws.onopen,ws.onclose,ws.onmessage,ws.onerror

举个栗子：

var ws_req = {
socket: null,
start: function() {
var Is_Flash_running = false;
var total_fail_count = 0;
if ("WebSocket" in window) {
var url = "ws://" + location.host + "/socket_req";
if (ws_req.socket){
ws_req.socket.close();
}
ws_req.socket = new WebSocket(url);
ws_req.socket.onopen = function() {
console.log("Opening a connection...");
ws_req.socket.send("connect to web server......")
};
ws_req.socket.onclose = function(evt) {
console.log("I'm sorry. Bye!");
};
ws_req.socket.onerror = function(evt) {
console.log("ERR: " + evt.data);
};
ws_req.socket.onmessage = function(event) {
try {
handleMessage(event.data);
} catch (err) {
console.log(err);
}
}
} else {
alert('你的浏览器太落伍了，换用高版本的chrome内核浏览器吧！！！');
}
},
}
ws_req.start();

var handleMessage = function(data){
//
}

web服务器实现：

笔者使用的后端开发语言是python，用的是Tornado web框架，tornado.websocket已经封装了websocket的协议，我们仅需简单的调用即可

import tornado.web
import tornado.websocket
import traceback

from device_serial_load import DevSerialLoadHandler

class LoadDevSerialSocketHandler(tornado.websocket.WebSocketHandler):
    client = set()

    def get_compression_options(self):
        # Non-None enables compression with default options.
        return {}

    def open(self):
        LoadDevSerialSocketHandler.client.add(self)

    def on_close(self):
        LoadDevSerialSocketHandler.client.remove(self)
        try:
            self.dslhler.dev_serial_load_client.stop()
        except Exception, e:
            logger.info('close socket client')

    def send_msg_to_broswer(self, msg):
        try:
            self.write_message(msg)
            return True
        except:
            logger.error(str(msg) + '发送失败')
            self.close()
            return False

    def on_message(self, message):
        message_json = json.loads(message)
        if "NodeID" in message_json and "LineNum" in message_json :
            node_ip = TestNodeData().get_node_ip(message_json["NodeID"])
            line_num = message_json["LineNum"][2]
            self.dslhler = DevSerialLoadHandler(node_ip, line_num, self.send_msg_to_broswer)
            self.dslhler.start()
        elif "InputMessage" in message_json:
            try:
                if message_json["InputMessage"] == "None":
                    # 支持网页仅回车键的发送
                    self.dslhler.dev_serial_load_client.client.send(" ")
                else:
                    self.dslhler.dev_serial_load_client.client.send(message_json["InputMessage"])
            except Exception, e:
                logger.error(e)
                logger.error(traceback.format_exc())
                logger.error("send input message to dev serial fail")
                self.send_msg_to_broswer("<span style='color:red;font-size:20px'>ATCServer:[串口命令发送失败]</span>
")

上诉代码将串口打印通过websocket实时的传输到web页面显示