websocket原理及實時投票
阿新 • • 發佈：2019-03-10
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WebSocket協議是基於TCP的一種新的協議。WebSocket最初在HTML5規範中被引用為TCP連接，作為基於TCP的套接字API的占位符。它實現了瀏覽器與服務器全雙工(full-duplex)通信。其本質是保持TCP連接，在瀏覽器和服務端通過Socket進行通信。
我們知道http協議是短連接,一次請求一次響應,如果我們想給客戶端推送消息,或者想實時的獲取數據我們是怎麽做的呢?
為了偽造這種效果我們用了輪詢和長輪詢,但是這裏也有弊端,服務端只能夠做出響應,且不能夠主動推送消息.
那麽誕生了一個新的協議,websocket協議,是基於http協議創建的.websocket其實就是web socket
他能夠不斷開連接的實時收發數據,且服務端能夠主動的給客戶端推送消息
Http, socket實現，短鏈接，請求響應
- WebSocket, socket實現，雙工通道，請求響應，推送，Socket創建連接，不斷開。
websocket
介紹
#1. 什麽是websocket？
是一套協議，協議規定了：
- 連接時需要握手
- 發送數據進行加密
- 連接之後不斷開
#2. websocket意義?
實時的響應頁面,且可以主動給客戶端推送消息
#3.websocket的兼容性
ie瀏覽器
#4.哪些框架支持websocket?
- flask gevent-websocket
- django channel
以上默認不支持
-tornado 框架自帶
socket入手實現websocket
- 服務端（socket服務端）
1. 服務端開啟socket，監聽IP和端口
3. 允許連接
* 5. 服務端接收到特殊值【加密sha1,特殊值,migic string="258EAFA5-E914-47DA-95CA-C5AB0DC85B11"】
* 6. 加密後的值發送給客戶端
- 客戶端（瀏覽器）
2. 客戶端發起連接請求（IP和端口）
* 4. 客戶端生成一個xxx，向服務端發送
* 7. 客戶端接收到加密的值
1. 啟動服務端
import socket sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) sock.bind((‘127.0.0.1‘, 8002)) sock.listen(5) # 等待用戶連接 conn, address = sock.accept()
接收data
data = conn.recive(8096)
headers = get_headers(data)
獲取握手消息，magic string sha1加密，然後發送給客戶端
conn.send
def get_headers(data): """ 將請求頭格式化成字典 :param data: :return: """ header_dict = {} data = str(data, encoding=‘utf-8‘) header, body = data.split(‘\r\n\r\n‘, 1) header_list = header.split(‘\r\n‘) for i in range(0, len(header_list)): if i == 0: if len(header_list[i].split(‘ ‘)) == 3: header_dict[‘method‘], header_dict[‘url‘], header_dict[‘protocol‘] = header_list[i].split(‘ ‘) else: k, v = header_list[i].split(‘:‘, 1) header_dict[k] = v.strip() return header_dictget_headers,將請求頭轉化為字典
請求頭的信息
GET /chatsocket HTTP/1.1 Host: 127.0.0.1:8002 Connection: Upgrade Pragma: no-cache Cache-Control: no-cache Upgrade: websocket Origin: http://localhost:63342 Sec-WebSocket-Version: 13 Sec-WebSocket-Key: mnwFxiOlctXFN/DeMt1Amg== Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits ... ...
import socket import base64 import hashlib def get_headers(data): """ 將請求頭格式化成字典 :param data: :return: """ header_dict = {} data = str(data, encoding=‘utf-8‘) header, body = data.split(‘\r\n\r\n‘, 1) header_list = header.split(‘\r\n‘) for i in range(0, len(header_list)): if i == 0: if len(header_list[i].split(‘ ‘)) == 3: header_dict[‘method‘], header_dict[‘url‘], header_dict[‘protocol‘] = header_list[i].split(‘ ‘) else: k, v = header_list[i].split(‘:‘, 1) header_dict[k] = v.strip() return header_dict def send_msg(conn, msg_bytes): import struct token = b"\x81" length = len(msg_bytes) if length < 126: token += struct.pack("B", length) elif length <= 0xFFFF: token += struct.pack("!BH", 126, length) else: token += struct.pack("!BQ", 127, length) msg = token + msg_bytes conn.send(msg) return True sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) sock.bind((‘127.0.0.1‘, 8002)) sock.listen(5) # 等待用戶連接 conn, address = sock.accept() # [握手消息] data = conn.recv(8096) headers = get_headers(data) # for k,v in headers.items(): # print(k,v) magic_string = ‘258EAFA5-E914-47DA-95CA-C5AB0DC85B11‘ value = headers[‘Sec-WebSocket-Key‘] + magic_string ac = base64.b64encode(hashlib.sha1(value.encode(‘utf-8‘)).digest()) response_tpl = "HTTP/1.1 101 Switching Protocols\r\n" "Upgrade:websocket\r\n" "Connection:Upgrade\r\n" "Sec-WebSocket-Accept:%s\r\n" "WebSocket-Location:ws://%s%s\r\n\r\n" # 獲取[握手消息]，magic string,sha1加密 # 發送給客戶端 response_str = response_tpl % (ac.decode(‘utf-8‘), headers[‘Host‘], headers[‘url‘]) conn.send(bytes(response_str, encoding=‘utf-8‘)) while True: info = conn.recv(8096) payload_len = info[1] & 127 if payload_len == 126: extend_payload_len = info[2:4] mask = info[4:8] decoded = info[8:] elif payload_len == 127: extend_payload_len = info[2:10] mask = info[10:14] decoded = info[14:] else: extend_payload_len = None mask = info[2:6] decoded = info[6:] bytes_list = bytearray() for i in range(len(decoded)): chunk = decoded[i] ^ mask[i % 4] bytes_list.append(chunk) body = str(bytes_list, encoding=‘utf-8‘) body = body + "是正文是是" send_msg(conn,bytes(body,encoding=‘utf-8‘))socket實現server.py
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <script> ws = new WebSocket("ws://127.0.0.1:8002"); ws.onopen = function () { console.log(1111); ws.send(‘hello村長‘) }; ws.onmessage = function (event) { console.log(event); }; ws.onclose = function () { } </script> </body> </html>socket實現client端
啟動Socket服務器後，等待用戶【連接】，然後進行收發數據。
2. 客戶端連接
基於flask的websocket應用
安裝第三方包:
pip install gevent-websocket
基於websocket的實時投票實例:
from flask import Flask,render_template,request from geventwebsocket.handler import WebSocketHandler from gevent.pywsgi import WSGIServer import json app = Flask(__name__) USERS = { ‘1‘:{‘name‘:‘鋼彈‘,‘count‘:0}, ‘2‘:{‘name‘:‘鐵錘‘,‘count‘:0}, ‘3‘:{‘name‘:‘貝貝‘,‘count‘:100}, } # http://127.0.0.1:5000/index @app.route(‘/index‘) def index(): return render_template(‘index.html‘,users=USERS) # http://127.0.0.1:5000/message WEBSOCKET_LIST = [] @app.route(‘/message‘) def message(): ws = request.environ.get(‘wsgi.websocket‘) if not ws: print(‘http‘) return ‘您使用的是Http協議‘ WEBSOCKET_LIST.append(ws) while True: cid = ws.receive() if not cid: WEBSOCKET_LIST.remove(ws) ws.close() break old = USERS[cid][‘count‘] new = old + 1 USERS[cid][‘count‘] = new for client in WEBSOCKET_LIST: client.send(json.dumps({‘cid‘:cid,‘count‘:new})) if __name__ == ‘__main__‘: http_server = WSGIServer((‘0.0.0.0‘, 5000), app, handler_class=WebSocketHandler) http_server.serve_forever()app.py
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="UTF-8"> <title>Title</title> <meta name="viewport" content="width=device-width, initial-scale=1"> </head> <body> <h1>醜男投票系統</h1> <ul> {% for k,v in users.items() %} <li onclick="vote({{k}})" id="id_{{k}}">{{v.name}}<span>{{v.count}}</span></li> {% endfor %} </ul> <script src="{{ url_for(‘static‘,filename=‘jquery-3.3.1.min.js‘)}}"></script> <script> var ws = new WebSocket(‘ws://192.168.13.253:5000/message‘) ws.onmessage = function (event) { /* 服務器端向客戶端發送數據時，自動執行 */ // {‘cid‘:cid,‘count‘:new} var response = JSON.parse(event.data); $(‘#id_‘+response.cid).find(‘span‘).text(response.count); }; function vote(cid) { ws.send(cid) } </script> </body> </html>index.html
websocket原理及實時投票