[This message was posted by Shashank Bhatt of Faculties India <[email protected]> to the "FAST Protocol" discussion forum at http://fixprotocol.org/discuss/46. You can reply to it on-line at http://fixprotocol.org/discuss/read/76b8f86c - PLEASE DO NOT REPLY BY MAIL.]
Hi all, Regarding Presence Map Overlong Property, according to spec "Logically a presence map has an infinite suffix of zeroes. This makes it possible to truncate a presence map that ends in a sequence where the bits are all zero." and "A presence map is overlong if it has more than seven bits and ends in seven or more bits that are all zero." As a receiver of FIX-FAST messages, whether overlong presence map might break the decoding? e.g. The correct wire representation is 1|1111100 and overlong representation is 0|1111100 1|0000000. Receiver is getting the overlong presence map. I think it should not break the decoding. Am I right? Thanks & regards Shashank > Hi Fernando, > > Following the correct PMAP for your case: 1111110 only one byte > with STOP bit. > > Suppose you have the 8th bit set then you will have : 11111100 11000000 > > A PMAP overlong will be generated for the 1st case with 5 bits set if > one sends: > > 01111100 10000000 => (R7) > > - Darshan > > > From the spec: A presence map is overlong if it has more than seven > > bits and ends in seven or more bits that are all zero. > > > > Also from the spec: Logically a presence map has an infinite suffix of > > zeroes. This makes it possible to truncate a presence map that ends in > > a sequence where the bits are all zero. > > > > So assuming I have 12 fields, and the last 7 fields are not in the > > message (lets assume they are all copy), I would have a PMAP: > > 111110000000 > > > > So... I don't understand how to detect if a PMAP if overlong, and if a > > message correctly has more than 7 fields and it happens the last 7 > > fields of the message are not in the message (they are implied by the > > PMAP) I would incorrectly flag the PMAP as overlong! > > > > Reportable Error R8 takes care of the PMAP having the exact > > representation (lenght wise) of the Template. So it can't be that... > > > > I don't know when Reportable Error R7 (PMAP is Overlong) happens. Can > > anyone shed some light on this issue please? [You can unsubscribe from this discussion group by sending a message to mailto:[email protected]] --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Financial Information eXchange" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/fix-protocol?hl=en -~----------~----~----~----~------~----~------~--~---
