Comet web applications with Python, Django & Orbited

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Comet web applicationswith Python, Django & Orbited @ PyCon Italia Qu4ttro http://www.pycon.it/ Massimo Scamarcia http://www.webright.it /

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Comet web applicationswith Python, Django & Orbited How to push real-time data to web browsers?

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Comet web applicationswith Python, Django & Orbited AJAX Polling Client: sends AJAX request.

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Server: Data available:sends response.

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No data: sendsempty response. Client: sends AJAX request again.

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Comet web applicationswith Python, Django & Orbited Latency, bandwidth, memory usage and scaling issues!

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Comet web applicationswith Python, Django & Orbited What about Comet?

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Comet web applicationswith Python, Django & Orbited Not a technology in itself

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Long Polling, IFRAMEstream, HTMLFile, XHR Streaming, HTML5 SSE

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Comet web applicationswith Python, Django & Orbited It's an hack!

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Still waiting foran unanimous way to do it.

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Comet web applicationswith Python, Django & Orbited Long Polling Client: sends AJAX request.

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Server: holds therequest. Data available: sends response.

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Timeout reached: emptyresponse. Client: sends AJAX request again.

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Comet web applicationswith Python, Django & Orbited Http Push (HTTP Streaming*) Client: sends HTTP request.

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Server: doesn't terminatethe connection.

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Server: sends datawhen available.

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Connection closed: Data is queued.

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Client reconnects. [*]http://ajaxpatterns.org/HTTP_Streaming

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Comet web applicationswith Python, Django & Orbited HTTP Push: better for heavily-loaded apps. Not cross-browser. Long Polling: cross-browser and easy. Bandwidth usage.

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Too many connections.Async Python servers* are better for both: Twisted, Tornado, Dieselweb, Eventlet, Concurrence, Circuits, Gevent, Cogen. [*] http://nichol.as/asynchronous-servers-in-python

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Comet web applicationswith Python, Django & Orbited What about Orbited?

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Comet web applicationswith Python, Django & Orbited He's here to solve problems!

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Comet web applicationswith Python, Django & Orbited Based on Twisted.

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STOMP* (ActiveMQ, RabbitMQ),IRC and XMPP protocol support.

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Ready-to-use and cross-browserJavaScript client code.

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You don't haveto reinvent the wheel! [*] http://stomp.codehaus.org/

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Comet web applicationswith Python, Django & Orbited Using Django and Orbited Example app developed for PyConIt4: http://pyconquiz.webright.it/

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Comet web applicationswith Python, Django & Orbited Django is used for: Application logic.

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Template rendering.

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User auth andregistration.

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Handling AJAX requests.

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Sending messages toSTOMP server. ...Orbited and jQuery do the rest!

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Comet web applicationswith Python, Django & Orbited

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Comet web applicationswith Python, Django & Orbited orbited.cfg [global] #reactor=select #reactor=kqueue reactor = epoll proxy.enabled = 1 session.ping_interval = 300 [listen] http://localhost:8080 stomp://localhost:61613 [access] * -> localhost:61613 settings.py # Available using context # processor or templatetag ORBITED_HOST = 'localhost' ORBITED_PORT = 8080 STOMP_HOST = 'localhost' STOMP_PORT = 61613

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Comet web applicationswith Python, Django & Orbited Django base template (<head /> tag) <script>document.domain = document.domain;</script> <script src="{{ ORBITED_MEDIA_URL }}Orbited.js"></script> <script type="text/javascript"> Orbited.settings.port = {{ ORBITED_PORT }}; Orbited.settings.hostname = "{{ ORBITED_HOST }}"; Orbited.settings.streaming = true; TCPSocket = Orbited.TCPSocket; </script> <script src="{{ ORBITED_MEDIA_URL }} JSON.js"></script> <script src="{{ ORBITED_MEDIA_URL }} protocols/stomp/stomp.js"></script>

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Comet web applicationswith Python, Django & Orbited <script> $(document).ready(function() { stomp = new STOMPClient(); stomp.onopen = function() { debug('Connected.');}; stomp.onclose = function(c) { debug(Lost Connection, Code: '+c);}; stomp.onerror = function(error){ debug("Error: " + error);}; stomp.onerrorframe = function(frame){ debug("Error: " + frame.body);}; stomp.onconnectedframe = function() { {% if game %} stomp.subscribe('/games/{{ game.id }}/status'); stomp.subscribe('/games/{{ game.id }}/players'); {% else %}// subscribe to other channels...{% endif %} }; stomp.onmessageframe = function(frame){ // frame.headers.destination for channel, frame.body for JSON data destpatterns.dispatch(frame); }; stomp.connect('{{ STOMP_HOST }}', {{ STOMP_PORT }}); }); </script>

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Comet web applicationswith Python, Django & Orbited Django view @require_POST @login_required def game_start(request, game_id): game = get_object_or_404(Game, id=game_id) if request.user != game.author: return HttpResponseForbidden() try: # start() method set game start_time and send JSON # to ”/games/{{ game.id }}/status” using stomp.py game.start() except GameError, e: return JSONResponse({'error': str(e)}) return JSONResponse({})

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Comet web applicationswith Python, Django & Orbited Does it scale?

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Comet web applicationswith Python, Django & Orbited Thank you and have fun with the quiz game!

Comet web applications with Python, Django & Orbited

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