old_contents: from flask import Flask, render_template
  from flask_socketio import SocketIO, send, emit
  app = Flask(__name__, template_folder='./templates')
  
  # Websocket setting
  app.config['SECRET_KEY'] = '12qwaszx'
  socketio = SocketIO(app)
  
  @app.route('/')
  def index():
      return render_template('index.html')    
  
  
  # @app.route('/<string:page_name>/')
  # def static_page(page_name):
  #     return render_template('%s.html' % page_name)    
  
  @socketio.on('message')
  def handle_message(message):
      print('received message: ' + message)    
  
  @socketio.on('connect_event')
  def connected_event(msg):
      print('Received msg: %s', msg)
      emit('server_response', {'data': msg['data']}, broadcast=True)
  
  @socketio.on('save receipt')
  def handle_json(json):
      print('Received json: ' + str(json))
      emit('save-reveipt response', {'isSuccess': 'true'})
  
  if __name__=='__main__':
      socketio.run(app)
  
new_contents: from flask import Flask, render_template, request, jsonify
  from flask_socketio import SocketIO, send, emit
  import json
  
  
  app = Flask(__name__, template_folder='./templates')
  
  # Websocket setting
  app.config['SECRET_KEY'] = '12qwaszx'
  socketio = SocketIO(app)
  
  @app.route('/')
  def index():
      return render_template('index.html')    
  
  @app.route('/send', methods=['GET', 'POST'])
  def send():
      """Receive a message and brodcast to all connected clients
      """
      jsonobj_content = request.json
      socketio.emit('server_response',  {'data':str(jsonobj_content)}, broadcast=True)
      return '', 200
  
  
  # @app.route('/<string:page_name>/')
  # def static_page(page_name):
  #     return render_template('%s.html' % page_name)    
  
  @socketio.on('connect_event')
  def connected_event(msg):
      """WebSocket connect event
      This will trigger responsing a message to client by 
      """
      print('Received msg: %s', msg)
      emit('server_response', {'data': msg['data']})
  
  if __name__=='__main__':
      socketio.run(app)
  
subject: Create a broadcast api: send