[Quickfixj-users] RE: [Quickfix-developers] QuickFix FailOver/Farming Support.

[Steve B. <sb...@sm...>]

Hi Phil,
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This feature is in QuickFIX/J. There is a RefreshableMessageStore
interface that provides the methods for refreshing the store and marks
which stores can be refreshed (MemoryStore can't, for example). The
Session can be configured to refresh it's state at logon if a
refreshable store is being used (see the "RefreshMessageStoreAtLogon"
configuration option). This might give you some ideas how to modify the
C++ code in a similar way.
=20
Regards,
=20
Steve


________________________________

	From: qui...@li...
[mailto:qui...@li...] On Behalf Of pc
redev
	Sent: Friday, May 26, 2006 6:07 PM
	To: Oren Miller; qui...@li...
	Subject: Re: [Quickfix-developers] QuickFix FailOver/Farming
Support.
=09
=09
	Oren,
	=20
	From looking at the source looks like "revert" would propbably
just call "populateCache()" on the message store's.  Not sure where
abouts in logon is the safest place to call this.
	=20
	What is the possibility of this being available in a future
release?  I'd prefer not to change the code for my system as creates
issues with Fix Fixengine releases.
	=20
	Also is there a way I can simulate this behaviour without
changing the "FixEngineCode".  Is it possible to make the session
"recreate" on the logon event, which would also have the same effect?
In the worst case I could expose the "PopulateCache" as a public method,
and call this on the "OnLogon", however I suspect this is too late as
you will have already started using the sequence number.   Any ideas on
workaround would be appreciated.
	=20
	Thanks
	Phil.
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	Oren Miller <or...@qu...> wrote:

		To do this we would need some sort of revert method on
the MessageStore interface which would revert to the persisted state.
This could then be called by a session when receiving a logon.  It
actually might be a useful thing to do in all logon situations.  It also
gives us the ability to modify sequence numbers and such without having
to restart the engine.
		=20
		--oren

			----- Original Message -----=20
			From: pc redev <mailto:pc....@ta...> =20
			To: qui...@li...=20
			Sent: Thursday, May 25, 2006 2:08 PM
			Subject: [Quickfix-developers] QuickFix
FailOver/Farming Support.

			Hi,=20
			=20
			I have a QuickFixEngine connected to a
"Clustered" MS SQL Server backend, running fine.  I would like to
be-able to provider "FailOver/Farming" support like:
			=20
			Primary Machine:  Fix Engine Running Serving
Active Clients
			Secondary Machine: Fix Engine Running in No
client connections.
			=20
			Both Fix Engines are connected to the clustered
SQL Server for the message store. =20
			=20
			If I "pull the plug" on A, clients are
disconnected and connect to "secondary", which in theory when they
connect we pick up the session from where it left off.
			=20
			The problem is the "Secondary" quick fix engine
does not know to "re-read" the clients "Sessions" when they connect, it
appears that this is performed when the "Fix Engine Starts Up" probably
during the create session.
			=20
			My only solution at the moment would be to have
the "Secondary" fix engine start on failover, i.e cold standby, which is
not ideal.=20
			=20
			In the Fix Engine logic is it possible to
"detect" a client socket connect and force a "re-read" of session
information from the message store  cleanly with no side effects?   I'd
prefer not to change the Fix engine source code. =20
			=20
			Any info would be appreciated.
			=20
			Regards
			=20
			Phil.
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