Re: [Quickfix-developers] Dealing with seqno

[Dale W. <wil...@oc...>]

Hi  Ananth,

Ananth wrote:

> QuickFIX Documentation: 
> http://www.quickfixengine.org/quickfix/doc/html/index.html QuickFIX 
> Support: http://www.quickfixengine.org/services.html
>
> Hi,
>
>  
>
> I have question regarding setting of seqnos...
>
>  
>
> We have an application by which a trader can login from any computer.
>
> But as per settings we are storing seqnos in file in particular computer.
>
> So whenever client logins in another computer I just extract expected 
> seq no. from logout  message sent by Server, and overwrite *outgoing 
> seqno* in respective file.
>
>  
>
> But my problem arises with *incoming seqno*. Because when the server 
> appln send next msg with its seqno, *ResendRequest* msg is generated 
> by client appln, normally sequence reset msg is sent by server, but at 
> times when seqno. gap is too high then it sends logout msg....In this 
> situation I cant overwrite incoming seqno, because it would have many 
> bad impacts in appln itself.
>
>  
>
> How to handle this situation.
>
> Pls give me some suggestion in this matter
>
One suggestion that may be obvious, but peopole often miss the obvious 
so I'll make it anyway:   Share the store directory between 
workstations.  The downside is you may take a performance hit, and there 
may be reliability issues due to single-point-of-failure and the latency 
in writing to the store.  But if you consider these factors and find the 
tolerable this is by-far the easiest approach.

If sharing the flat files doesn't meet you needs, consider using MySQL 
or some other database to store the files on a server.  You still risk a 
perfomance hit, but the reliability issue should ber handled by the 
database.

One reason I think you may not be concerned about reliability is the 
technique you are using now is very risky.  Do you have any mechanism to 
insure that a trader doesn't log onto two workstations at the same 
time?  If a trader walks away from a running workstation, and logs into 
another there are a variety of things that could go wrong (and very few 
that could go right!)

Dale

>  
>
>  
>
> Thanks in Advance,
> Ananth
>
>
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-- 
-----------------------------------------------------
  Dale Wilson, Senior Software Engineer
  Object Computing, Inc. (OCI)
  http://www.ociweb.com/  http://www.theaceorb.com/
----------------------------------------------------