Re: [Quickfix-developers] Configuration Failover Settings

[Jon D. <jd...@wi...>]

Understood. However we are setting ResetOnDisconnect and ResetOnLogout to
1 so I would assume session state is not that big of a deal then. Unless
of course I am reading the config documentation incorrectly.

jd

> Well you need to determine what it is exactly you are trying to make
> redundant.  If you are trying to make the FIX session redundant, than
> you should have the same compids while making sure that only one server
> is active at any given time.  These processes should share the same
> source for the state of the session.  This way no matter where they
> connect to, the sequence numbers will be the same.  In this case flat
> file storage probably won't do, in which case you would likely want to
> use a database.  For extra reliability you would also want to make the
> database redundant.
>
> Now if you are simply trying to provide redundant lines, then you
> should use different compids.  In this case you are not making the
> session redundant, but you are making sure that they always have a path
> into the system.  The upside is that these lines are always on and are
> immediately available to accept traffic.  In fact they can accept
> traffic simultaneously (distributing the load), and the client can
> reroute excess traffic to the other lines if one goes down.  The
> downside is that if a session goes down, lost messages won't be
> retrieved until it can be brought back up.
>
> You can also combine these by having redundant paths into the system
> which have redundant sessions.  It all depends on what you are trying
> to accomplish.  But the thing that should remain solid is that if I am
> connecting somewhere with the same compids, I should expect the
> sequence numbers to carry over.  If not, I can only assume something is
> catastrophically wrong and manual intervention is required.
>
> --oren
>
> On Jun 9, 2004, at 12:51 PM, Jon Dahl wrote:
>
>> I understand about having the same SenderCompID's. SenderLocationID
>> can be
>> used instead of the SenderCompID to indentify the source of the
>> message.
>>
>> But in the case of a failover, won't sequence numbers be an issue? If
>> the failover server sequence numbers for a client were higher than
>> what
>> the client was at, wouldn't there be a possiblity of a resend or
>> locking
>> the client out until the sequence numbers caught up?
>>
>> jd
>>
>>> John,
>>>
>>> When you have multiple connection points that share the same comp
>>> id's,
>>> cycling through the connections is a necessity because you can't keep
>>> the same session alive simultaneously on multiple hosts/ports.  But
>>> if you failover sessions with unique compids and unique sets of
>>> sequence numbers, why would you not just keep these connections up at
>>> all  times?
>>>
>>> --oren
>>>
>>> On Jun 9, 2004, at 10:46 AM, Jon Dahl wrote:
>>>
>>>> QuickFIX Documentation:
>>>> http://www.quickfixengine.org/quickfix/doc/html/index.html
>>>> QuickFIX FAQ:
>>>> http://www.quickfixengine.org/quickfix/doc/html/FAQ.html
>>>>
>>>> I have been asked to research QuickFIX's scalability/failover
>>>> capabilities
>>>> by our Ops center and have come upon an issue. I think I found a
>>>> situation
>>>> where the clients won't be able to connect to an alternate gateway
>>>> in case
>>>> of a failure.
>>>>
>>>> Let's say a client has two hosts(gateways) to connect to. Each one
>>>> has
>>>>  a
>>>> separate SenderCompID. If the client detects a failure and tries to
>>>> connect to the secondary host, it will fail to connect because its
>>>> TargetCompID is for the primary host and not the secondary one.
>>>>
>>>> I was wondering if there was a way to have the [SESSION] settings
>>>> have
>>>> alternate TargetCompID's to go a long with SocketConnectPort[n] and
>>>> SocketConnectHost[n]?
>>>>
>>>> JD
>>>>
>>>>
>>>>
>>>>
>>>>
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>>
>> --
>> Jon Dahl
>> jd...@wi...


-- 
Jon Dahl
jd...@wi...