A cherrypy websockets server to broadcast, eg. for system monitoring

cherrypy-websockets-monitor.py

# To use this, you need to implement some class with a read() method, eg.
#
# class MyReader(object):
#     def __init__(self, path):
#         self.path = path
#
#     def read(self):
#         with open(self.path, 'r') as f:
#             return f.read()
# ...
#
#  myReader = MyReader('/etc/motd')
#

try:
    import wsaccel
    wsaccel.patch_ws4py()
except ImportError:
    pass

from ws4py.server.cherrypyserver import WebSocketPlugin, WebSocketTool
from ws4py.websocket import WebSocket

import cherrypy
from cherrypy.process import plugins

BASE_URL = None

bus = cherrypy.engine


class MonitorWebSocketHandler(WebSocket):
    def received_message(self, m):
        self.send(bus.websockets.currentData)

class MonitorWebSocketPlugin(WebSocketPlugin):
    def __init__(self, bus, reader):
        WebSocketPlugin.__init__(self, bus)

        self.reader = reader
        self.currentData = reader.read()
        plugins.Monitor(bus, self.broadcastChanges, 0.1).subscribe()

    def broadcastChanges(self):
        newData = self.reader.read()
        if (newData != self.currentData):
             bus.publish('websocket-broadcast', newData)
             self.currentData = newData

myReader = ## Some object with a read() method that returns whatever you want to broadcast
                               
cherrypy.tools.websocket = WebSocketTool()
bus.websockets = MonitorWebSocketPlugin(bus, myReader)
                               
class Root(object):            
    @cherrypy.expose           
    def index(self):           
        return myReader.read()
                               
    @cherrypy.expose           
    @cherrypy.tools.websocket(handler_cls=MonitorWebSocketHandler)
    def ws(self):              
        handler = cherrypy.request.ws_handler
        cherrypy.log("Handler created: %s" % repr(handler))
                               
def CORS():                    
    cherrypy.response.headers["Access-Control-Allow-Origin"] = "*"
                               
if __name__ == '__main__':     
    bus.websockets.subscribe() 

    conf = {
        '/': {
            'tools.CORS.on': True,
        },
        '/ws': {
            'tools.CORS.on': True,
            'tools.websocket.on': True,
            'tools.websocket.handler_cls': MonitorWebSocketHandler
        }
    }
    cherrypy.tools.CORS = cherrypy.Tool('before_finalize', CORS)
    cherrypy.server.socket_host = '0.0.0.0'

    app = Root()

    cherrypy.tree.mount(app, '/', config=conf)
    cherrypy.config.update(conf)

    bus.signals.subscribe()
    bus.start()
    bus.block()
    

See also: https://github.com/Lawouach/WebSocket-for-Python/blob/master/example/basic/app.py