Re: Client reconnecting from Websockets in Python

[Tobias Oberstein]

Am 20.06.2013 16:35, schrieb Kevin Campion:
> Hi,
>
> I am trying to get Autobahn.Python to work with disconnecting when
> server down, without having to restart the program. The client program
> must try to reconnect every x seconds to the server.
>
> My source code works but when client reconnects, I can see in server's
> log multiple connection for the same client. I have an
> additional connection per trying reconnection.
>
> I think, it's when I use "connector.connect()"

Yep, sounds a bit like you are piling up new clients which each tries
to reconnect again and again.

Probably instead of implementing a reconnection policy yourself (yes, we
are guilty of that also), we should use

http://twistedmatrix.com/documents/current/api/twisted.internet.protocol.ReconnectingClientFactory.html
http://twistedmatrix.com/documents/13.0.0/core/howto/clients.html

The "problem" is, Autobahn (currently) defines


class WebSocketClientFactory(protocol.ClientFactory, WebSocketFactory):
"""
A Twisted factory for WebSocket client protocols.
"""

protocol = WebSocketClientProtocol

==

Probably this works:

class MyFactory(ReconnectingClientFactory, WebSocketClientFactory)

Not sure, cannot test right now.

Possibly, the empty implementation in
WebSocketClientFactory.clientConnectionFailed and clientConnectionLost
are "in the way" ..

Anyway, I'd try to either use ReconnectingClientFactory or have a look
at the implementation.

/Tobias


>
> I use this discussion and the example on GitHub :
> https://groups.google.com/forum/?fromgroups#!searchin/autobahnws/reconnect|sort:relevance/autobahnws/HCNFWKGYQCM/G1EGNGxOZXkJ
> https://github.com/tavendo/AutobahnTestSuite/blob/master/autobahntestsuite/autobahntestsuite/testee.py#L87
> <https://github.com/tavendo/AutobahnTestSuite/blob/master/autobahntestsuite/autobahntestsuite/testee.py#L87>
>
>
> My TesteeClientFactory class looks like this :
>
> class TesteeClientFactory(WebSocketClientFactory):
> protocol = TesteeClientProtocol
> def clientConnectionLost(self, connector, reason):
> connector.connect()
>
> def clientConnectionFailed(self, connector, reason):
> print "Connection to %s failed (%s)" % (self.url,
> reason.getErrorMessage())
> self.tryToConnect(connector)
> def tryToConnect(self, connector):
> connector.disconnect()
> var = 1
> while var == 1 :
> time.sleep( 2 )
> newConnection = connector.connect()
> if newConnection != None:
> break
> connector.disconnect()
>
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>

[Tobias Oberstein]

[Kevin Campion]

Well, I found the solution thanks to you.

1) When you use the source code with "connector.connect()" on "clientConnectionLost" and "clientConnectionFailed", like my previous email; if server is down, the client will try to reconnect every time as he can (3 times per second or more)

2) When you use the source code with "ReconnectingClientFactory"; if server is down, the client will try to reconnect and if he failed, he tries after 2 secondes, and after 6 seconds, and after 8 seconds... until 3600 seconds (by default)

Look my example, I block the max delay to 10 seconds :

class TesteeClientFactory(ReconnectingClientFactory, WebSocketClientFactory):

    protocol = TesteeClientProtocol

    def startedConnecting(self, connector):

        print 'Started to connect.'

    def buildProtocol(self, addr):

        print 'Connected.'

        

        self.maxDelay = 10

        return WebSocketClientFactory.buildProtocol(self, addr)

    def clientConnectionLost(self, connector, reason):

        print 'Lost connection.  Reason:', reason

        ReconnectingClientFactory.clientConnectionLost(self, connector, reason)

    def clientConnectionFailed(self, connector, reason):

        print 'Connection failed. Reason:', reason

        ReconnectingClientFactory.clientConnectionFailed(self, connector,

                                                         reason)

Thank you for your help.

[Tobias Oberstein]

Hi Kevin,

yes, the ReconnectingClientFactory code does (jitter'ed) exponential
backoff.

I've added an example to the repo:

https://github.com/tavendo/AutobahnPython/blob/master/examples/websocket/echo/client_reconnecting.py

/Tobias

Am 21.06.2013 12:14, schrieb Kevin Campion:
> Well, I found the solution thanks to you.
>
> 1) When you use the source code with "connector.connect()" on
> "clientConnectionLost" and "clientConnectionFailed", like my previous
> email; if server is down, the client will try to reconnect every time as
> he can (3 times per second or more)
>
> 2) When you use the source code with "ReconnectingClientFactory"; if
> server is down, the client will try to reconnect and if he failed, he
> tries after 2 secondes, and after 6 seconds, and after 8 seconds...

> until 3600 <tel:3600> seconds (by default)

>
> Look my example, I block the max delay to 10 seconds :
>
> class TesteeClientFactory(ReconnectingClientFactory,
> WebSocketClientFactory):
>
> protocol = TesteeClientProtocol
>
> def startedConnecting(self, connector):
> print 'Started to connect.'
>
> def buildProtocol(self, addr):
> print 'Connected.'
> self.maxDelay = 10
>
> return WebSocketClientFactory.buildProtocol(self, addr)
>
> def clientConnectionLost(self, connector, reason):
> print 'Lost connection. Reason:', reason
> ReconnectingClientFactory.clientConnectionLost(self, connector,
> reason)
>
> def clientConnectionFailed(self, connector, reason):
> print 'Connection failed. Reason:', reason
> ReconnectingClientFactory.clientConnectionFailed(self, connector,
> reason)
>
>
> Thank you for your help.
>

[Kevin Campion]

Thank you

[Ash Clarke]

URL 404'd,

new url for anyone looking

https://github.com/tavendo/AutobahnPython/blob/master/examples/twisted/websocket/echo_variants/client_reconnecting.py

[James Firth]

Hi I was looking at the new example and apparently mis-understand something.

I was told to use "ReconnectingClientFactory.resetDelay()" after the connection has completed due to the reconnect back-off.

if I place that line in MyClientProtocol.onConnect I get a loop of connection losses/reconnect attempts.

If I place it in MyClientProtocol.onOpen I get an error that I need an instance of ReconnectingClientFactory.

Where is the proper place to put "ReconnectingClientFactory.resetDelay()"?

Thanks!

[meejah]

On Friday, 11 September 2015 11:43:24 UTC-6, James Firth wrote:

 

Where is the proper place to put "ReconnectingClientFactory.resetDelay()"?

 

Hi James,

This works for me:  https://github.com/tavendo/AutobahnPython/pull/522/files

--
meejah

[James Firth]

This appears to have helped a lot, thanks!