Re: [Quickfixj-users] How to trigger a failover from the user code?

[Colin D. <co...@ma...>]

The solution I would prefer (and I would be willing to help work on it) 
would be to rely on an interface which provides a selection strategy. 
The simplest one could simply round-robin and OP could sub in a more 
complicated one with arbitrary inputs.

On 3/26/21 5:43 PM, Christoph John wrote:
> This is a valid point. I think neither logic can satisfy all cases. 
> Actually the current logic was introduced only two versions ago with 
> https://github.com/quickfix-j/quickfixj/pull/152 and would switch back 
> to the first host after a disconnection, no matter what. E.g. if there 
> was a seqnum-too-low mismatch at host 3 (after host 1 and 2 were 
> unreachable) it would then switch back to host 1, so no difference there.
>
> Cheers,
> Chris.
>
>
>
> On 27.03.21 01:34, Colin DuPlantis wrote:
>> QuickFIX/J Documentation:http://www.quickfixj.org/documentation/
>> QuickFIX/J Support:http://www.quickfixj.org/support/
>>
>>
>>
>> I would think we would want to be careful about introducing semantics 
>> where a successful network connection still resulted in switching to 
>> the next host if the counter disconnected.
>>
>> For example, what if the wrong sequence number is sent? We wouldn't 
>> want to fail to the next host then, right? How would we tell the 
>> difference between that usecase and this one where the counter is 
>> disconnecting a valid network connection for business reasons.
>>
>> On 3/26/21 5:31 PM, Christoph John via Quickfixj-users wrote:
>>> QuickFIX/J Documentation:http://www.quickfixj.org/documentation/
>>> QuickFIX/J Support:http://www.quickfixj.org/support/
>>>
>>>
>>>
>>> Hi,
>>>
>>> unfortunately it is not possible to do this.
>>> The only thing I could think of at the moment is to configure two 
>>> separate sessions, each with its own SocketConnectHost and do the 
>>> failover between the two sessions in the application logic. Or 
>>> simply let both run and CME reject one of the sessions when it tries 
>>> to connect.
>>>
>>> The failover logic in QFJ only works when the connection is 
>>> unsuccessful. However, by CME accepting the connection the logic is 
>>> getting tricked.
>>> I think it would be not so difficult to change this. We could 
>>> introduce a configuration which switches between the current 
>>> behaviour (Next connection attempt after a successful connection 
>>> will start at first defined connection again) and a round-robin one 
>>> which cycles through the hosts regardless of whether the last 
>>> connection was successful or not.
>>>
>>> Cheers,
>>> Chris.
>>>
>>>
>>>
>>> On 26.03.21 23:39, Andrew Gurinovich wrote:
>>>> QuickFIX/J Documentation:http://www.quickfixj.org/documentation/
>>>> QuickFIX/J Support:http://www.quickfixj.org/support/
>>>>
>>>>
>>>>
>>>> Hi.
>>>> When you connect and try to LOGIN to secondary(backup) IP address 
>>>> for CME fix dropcopy while the primary host is active, you are 
>>>> getting an LOGOUT:
>>>>
>>>> "8=FIX.4.2|35=5|49=CME|58=Backup session not allowed. Logout forced".
>>>>
>>>> You are supposed to failover to the other host then.
>>>>
>>>> We can handle the logout event in Application.fromAdmin, but i 
>>>> cant seem to find a way to failover to another SocketConnectHost 
>>>> manually - the Session does not expose 
>>>> IoSessionInitiator.getNextSocketAddress(where the address is 
>>>> updated). And even if it was exposed, after the LOGOUT happens the 
>>>> initiator is recreated, starting with the same first SocketConnectHost.
>>>>
>>>> Is there a way to trigger a failover manually in fromAdmin method 
>>>> in the Application?
>>>> Thanks!
>>>>
>>>>
>>>> _______________________________________________
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>>>> https://lists.sourceforge.net/lists/listinfo/quickfixj-users
>>>
>>> -- 
>>> Christoph John
>>> Software Engineering
>>> T +49 241 557080-28
>>> chr...@ma...
>>>
>>> MACD GmbH
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>>>
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>>>
>>>
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>> -- 
>> Colin DuPlantis
>> Chief Architect, Marketcetera
>> Download, Run, Trade
>> 888.868.4884
>> https://www.marketcetera.com
>>
>>
>> _______________________________________________
>> Quickfixj-users mailing list
>> Qui...@li...
>> https://lists.sourceforge.net/lists/listinfo/quickfixj-users
>
> -- 
> Christoph John
> Software Engineering
> T +49 241 557080-28
> chr...@ma...
>
> MACD GmbH
> Oppenhoffallee 103
> 52066 Aachen, Germany
> www.macd.com
>
> Amtsgericht Aachen: HRB 8151
> Ust.-Id: DE 813021663
> Geschäftsführer: George Macdonald

-- 
Colin DuPlantis
Chief Architect, Marketcetera
Download, Run, Trade
888.868.4884
https://www.marketcetera.com