Re: [Quickfix-developers] Recovering from a crash

[Oren M. <or...@qu...>]

Patrick,

In the toApp call you can choose to not send a message by throwing a=20
DoNotSend exception.  In the case of a resend, the message that would=20
have gone out is replaced with a gap fill.  If you do not send=20
consecutive messages, they will all be replaced with a single gap fill=20=

to the appropriate sequence number (instead of sending many individual=20=

gap fills).  You can always check to see if a message is being resent=20
by checking if the PossDup flag is set to 'Y'.  Many systems choose not=20=

to resend such requests for market dependent messages like orders, but=20=

will allow other requests like cancels to go through.

There is not configuration setting since with the DoNotSend=20
functionality, your app has total control and can determine your own=20
simple or complex rules for when you want to resend versus gap fill.

QuickFIX will attempt to automatically recover from sequence number=20
mismatches on logon (as the spec requires).  There shouldn't be an=20
infinite loop, although do not a bug fix was recently applied that did=20=

correct such a scenario under rare circumstances.  This has been=20
confirmed fixed in the CVS version.  The FIX specification also=20
recommends that you not send any application level messages until you=20
can confirm that your sequence numbers are synchronized.  You can=20
confirm this by sending a test request with a unique string, and=20
holding off on sending any new application level messages until you=20
receive the heartbeat response with your string.

On May 6, 2004, at 4:02 PM, Patrick Flannery wrote:

> Developers,
>
> =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 We are using a third party component =
to connect to an=20
> exchange; we are then using quick fix to communicate with this third=20=

> party component.=A0 When the third party component crashes =
unexpectedly=20
> we would like to restore state but not send any queued requests.=A0 =
Does=20
> quick fix automatically fill the gap in sequence numbers when it tries=20=

> to logon again?=A0 Does quick fix ever go into an infinite loop trying=20=

> to logon again?=A0 What should the configuration settings be so that=20=

> requests are never sent after a crash?=A0 Any suggestions you have for=20=

> dealing with the unexpected failure of a third party component would=20=

> be much appreciated.
>
> Thank you in advance.
>
> Patrick
>
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