I have an existing Python system that receives messages using Rabbit MQ. What is the absolute easiest way to get these events pushed to a browser using WebSockets using Python? Bonus if the solution works in all major browsers too.
Thanks,
Virgil
Here https://github.com/Gsantomaggio/rabbitmqexample I wrote an complete example that uses tornado and RabbitMQ.
You can find all the instruction from the site:
anyway ..you need:
pip install pika
pip install tornado
First you register your rabbitmq:
def threaded_rmq():
channel.queue_declare(queue="my_queue")
logging.info('consumer ready, on my_queue')
channel.basic_consume(consumer_callback, queue="my_queue", no_ack=True)
channel.start_consuming()
then you register your web-sockets clients:
class SocketHandler(tornado.websocket.WebSocketHandler):
def open(self):
logging.info('WebSocket opened')
clients.append(self)
def on_close(self):
logging.info('WebSocket closed')
clients.remove(self)
When you get a message, you can redirect it to the web-socket page.
def consumer_callback(ch, method, properties, body):
logging.info("[x] Received %r" % (body,))
# The messagge is brodcast to the connected clients
for itm in clients:
itm.write_message(body)
You could use Twisted, txAMQP and Autobahn|Python on the server to write a bridge in probably 50 lines of code, and Autobahn|JS on the browser side. Autobahn implements WebSocket, and WAMP on top, which provides you with Publish & Subscribe (as well as Remote Procedure Calls) over WebSocket.
When using raw WebSocket you would have to invent your own Publish & Subscribe over WebSocket - since I guess that is what you are after: extending the AMQP PubSub to the Web. Or you could check out STOMP.
Disclaimer: I am original author of WAMP and Autobahn.
Related
I have a very simple Python (Flask socket.io) application which works as a server and another app written in AngularJS which is a client.
In order to handle connected and disconnected client I use respectlivy:
#socketio.on('connect')
def on_connect():
print("Client connected")
#socketio.on('disconnect')
def on_disconnect():
print("Client disconnected")
When Client connects to my app I get information about it, in case if client disconnect (for example because of problems with a network) I don't get any information.
What is the proper way to handle the situation in which client disconnects unexpectedly?
There are two types of connections: using long-pooling or WebSocket.
When you use WebSocket clients knows instantly that server was disconnected.
In the case of long-polling, there is need to set ping_interval and pint_timeout parameters (I also find information about heartbeat_interval and heartbeat_timeout but I don't know how they are related to ping_*).
From the server perspective: it doesn't know that client was disconnected and the only way to get that information is to set ping_interval and ping_timeout.
I am trying to learn Twisted, a Python framework, and I want to put a basic application online that, when it receive a message sends it back. I decided to use Heroku to host it, and I followed the instructions on their docs.
import os
from twisted.internet import protocol, reactor
class Echo(protocol.Protocol):
def dataReceived(self, data):
self.transport.write(data)
class EchoFactory(protocol.Factory):
def buildProtocol(self, addr):
return Echo()
port = int(os.environ.get('PORT', 5000))
reactor.listenTCP(port, EchoFactory(), interface = '0.0.0.0')
reactor.run()
Its all working except (and I know this is a stupid question), how do I send a message to it? When I am working locally I just do telnet localhost <port>, but now I have no idea.
Also, since heroku connects to a random port how can I know what port it connects my app to?
Thanks.
I'm not very familiar with Twisted, but I'm not sure what you're trying to do is supported on Heroku. Heroku currently only supports HTTP[S] requests and not raw TCP. There are more details in the answers to this question.
If you wanted to connect to your app, you should use the myapp.herokuapp.com host name or any custom domain that you've added.
"Pure Python applications, such as headless processes and evented web frameworks like Twisted, are fully supported on Cedar."
Reference: https://devcenter.heroku.com/articles/python-support
I have a python script that will run on a local machine that needs to access a message queue (RabbitMQ) or receive subscribed events over HTTP. I've researched several solutions, but none seem natively designed to allow desktop clients to access them over HTTP. I'm thinking that using Twisted as a proxy is an option as well. Any guidance or recommendations would be greatly appreciated. Thanks in advance.
I've read this tutorial on RabbitMQ site, and they provide name of some libraries that could solve receiving messages.
Sender: send.py
#!/usr/bin/env python
import pika
connection = pika.BlockingConnection(pika.ConnectionParameters(
host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='hello')
channel.basic_publish(exchange='',
routing_key='hello',
body='Hello World!')
print " [x] Sent 'Hello World!'"
connection.close()
Receiver: receive.py
#!/usr/bin/env python
import pika
connection = pika.BlockingConnection(pika.ConnectionParameters(
host='localhost'))
channel = connection.channel()
channel.queue_declare(queue='hello')
print ' [*] Waiting for messages. To exit press CTRL+C'
def callback(ch, method, properties, body):
print " [x] Received %r" % (body,)
channel.basic_consume(callback,
queue='hello',
no_ack=True)
channel.start_consuming()
Now we can try out our programs in a terminal. First, let's send a message using our send.py program:
$ python send.py
[x] Sent 'Hello World!'
The producer program send.py will stop after every run. Let's receive it:
$ python receive.py
[*] Waiting for messages. To exit press CTRL+C
[x] Received 'Hello World!'
Hurray! We were able to send our first message through RabbitMQ. As you might have noticed, the receive.py program doesn't exit. It will stay ready to receive further messages, and may be interrupted with Ctrl-C.
Try to run send.py again in a new terminal.
We've learned how to send and receive a message from a named queue. It's time to move on to part 2 and build a simple work queue.
I've decided to use wamp http://wamp.ws/. Still experimenting with it, but it's working quite well at the moment.
Choice #1
You may be interested in this RabbitHub
Choice #2
If you want it to be on port#80, cant you do port forwarding using a proxy? It could be challenging, but
Choice #3
If your script is not tightly coupled with RMQ message format , you can try celery ( which uses RMQ underneath), then u can try celery Http gateway or celery web hooks if u want any other application to be triggered directly
It might be time consuming to get it up. However, Celery opens up loads of flexibility
Choice #4
For one of my projects, I developed an intermediate web service (Flask Service) to use RMQ
Not ideal, but it served the purpose at that time.
I am trying to learn Twisted, a Python framework, and I want to put a basic application online that, when it receive a message sends it back. I decided to use Heroku to host it, and I followed the instructions on their docs.
import os
from twisted.internet import protocol, reactor
class Echo(protocol.Protocol):
def dataReceived(self, data):
self.transport.write(data)
class EchoFactory(protocol.Factory):
def buildProtocol(self, addr):
return Echo()
port = int(os.environ.get('PORT', 5000))
reactor.listenTCP(port, EchoFactory(), interface = '0.0.0.0')
reactor.run()
Its all working except (and I know this is a stupid question), how do I send a message to it? When I am working locally I just do telnet localhost <port>, but now I have no idea.
Also, since heroku connects to a random port how can I know what port it connects my app to?
Thanks.
I'm not very familiar with Twisted, but I'm not sure what you're trying to do is supported on Heroku. Heroku currently only supports HTTP[S] requests and not raw TCP. There are more details in the answers to this question.
If you wanted to connect to your app, you should use the myapp.herokuapp.com host name or any custom domain that you've added.
"Pure Python applications, such as headless processes and evented web frameworks like Twisted, are fully supported on Cedar."
Reference: https://devcenter.heroku.com/articles/python-support
I have a web server running on Django.
Users can create events postponed in time.
These events must be recorded in queue and processed on another server.
Initially I thought to take the Twisted. something like:
#client - django server
factory = pb.PBClientFactory()
reactor.connectTCP(server_ip, server_port, factory)
d = factory.login(credentials.UsernamePassword(login, paswd),)
d.addCallbacks(self.good_connected,self.bad_connected)
d.addCallback(self.add_to_queue)
reactor.run()
def add_to_queue(self, p)
p.callRemote("pickup", data)
#server - twisted server
def perspective_pickup(self, data)
reactor.callLater(timeout, self.pickup_from_queue)
But now I have big doubts about this approach. Maybe do not use twisted? or connect it with Django differently
Run twisted inside of Django is not a good idea anyway. So, try Celery or run HTTP server with twisted and use urllib on django side to send data to twisted server.