WebSocket Server sending messages periodically in python
I have a tornado web server in python:
import tornado.httpserver
import tornado.websocket
import tornado.ioloop
from tornado.ioloop import IOLoop
import tornado.web
import time
import threading
import sys
from datetime import datetime
from datetime import timedelta
def sample():
print 'hiiiii'
threading.Timer(10, sample).start()
class WSHandler(tornado.websocket.WebSocketHandler):
def open(self):
print 'new connection'
def on_message(self, message):
self.write_message(message)
self.msg('hellooooooo')
print message
def msg(self,message):
self.write_message(message)
threading.Timer(10, self.msg('in timer')).start()
print 'in msg'+message
def on_close(self):
print 'connection closed'
application = tornado.web.Application([
(r'/', WSHandler),
])
if __name__ == "__main__":
http_server = tornado.httpserver.HTTPServer(application)
http_server.listen(8888)
interval_ms=120
main_loop=tornado.ioloop.IOLoop.instance()
main_loop.start()
And the client is
<html>
<head>
<script>
function fun(){
alert("in fun()");
var val=document.getElementById("txt");
var ws = new WebSocket("ws://localhost:8888");
ws.onopen = function(evt) { alert("Connection open ...");
ws.send(val.value); };
ws.onmessage = function(evt) {
alert("from server: "+evt.data);
}
ws.onclose = function(evt) {
alert("Connection closed.");
}
}
</script>
</head>
<body bgcolor="#FFFFFF">
<input type="text" id="txt" />
<button onClick="fun()">click</button>
</body>
</html>
I want to get the message periodically to the client. But when I try this I get this error: RunTimeError :Maximum Recursion Depth Exceeded. Please help me solve this issue. Also, how do we know what are the clients connected to the server?
Answer
Here's a minimal example using the PeriodicCallback.
import tornado.httpserver
import tornado.websocket
import tornado.ioloop
from tornado.ioloop import PeriodicCallback
import tornado.web
class WSHandler(tornado.websocket.WebSocketHandler):
def open(self):
self.callback = PeriodicCallback(self.send_hello, 120)
self.callback.start()
def send_hello(self):
self.write_message('hello')
def on_message(self, message):
pass
def on_close(self):
self.callback.stop()
application = tornado.web.Application([
(r'/', WSHandler),
])
if __name__ == "__main__":
http_server = tornado.httpserver.HTTPServer(application)
http_server.listen(8888)
tornado.ioloop.IOLoop.instance().start()