Re: PossDup and PossResend queries
SriPavan Thayaparan <>
25 Jul 2008 2:46AM ET
Hi Mary,
PossDup and PossResend are two flavours of the same mechanism by which the client can re-send messages in the event the client "suspects" data loss.
In a nut-shell....
1. Poss Dup - Means the client is re-sending a message with the same sequence number of the original.
2. Poss Resend - Means the client is re-sending a message with a newly stamped sequence number
Both these methods are session level re-transmission options and are not specific to a particular message type (G in your case), and that it applies in general to any message.
Now coming to how one should handle both...
1. Poss Dup - As the name conveys, is a duplicate. Its being re-sent by the client with the same sequence number. If your receiving application has already got this sequence number, then "just ignore". Else update your system with that message. This can be concluded at the session level itself since the sequence number itself is enough to decide whether its a duplicate for the receiver indeed.
2. Poss Resend - Its again re-transmission but with new sequence numbers. Hence, here to validate whether the message is a duplicate, sequence number is of no use. This validation should take place in the application layer. Hence this requires knowledge of the message type.
The methods are.....
For New(D) / Amend(G) / Cancel(F)- Validate whether the "Client Order ID" of the message in question is already received or not. If its a duplicate, then discard.
For Executions (8) - Validate the "ExecID" for duplicates.
In your case... (For G) if a client sends you a message with Pos Resend, validate the Client Order ID to see if its duplicate. If so, just drop it.
There is no requirement to convey any information on the acceptance of re-transmission. Its either take or discard.
Hope this helped you!
Best Regards,
Thaya.
> Can someone please tell me what is the expected behavior from the broker
> when the broker receives (from the client) an Order Cancel/Replace
> Request (MsgType G) or an Order Cancel Request (MsgType F) with Tag 97
> PossResend = ‘Y’ where the message is determined by the broker to be a
> duplicate. Should the broker send back a message to the client and if so
> what message? Or should the broker just ignore the order request and not
> send anything back to the client?
>
> Can someone also please tell me what response is required from the
> broker when Tag 43 PossDup is set to ‘Y’ (and Tag 97 PossResend has not
> been provided) in a New Order Single, Replace Request and Cancel Request
> where the broker again has determined that the message is a duplicate?
