[This message was posted by Hei Chan of N/A <[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/2d89c078 - PLEASE DO NOT REPLY BY MAIL.]
Thanks for the cheat sheet. It is very helpful ;-) > Hi Hei, > > > I am trying to understand the presence map better. > > The presence map bits are only used for fields that might not be on the > wire. The combination of field operator and presence attribute > determines whether the bit is needed. > > As Rolf explained, in your example, a field with no operator is ALWAYS > on the wire, so no presence map bit is needed. If the string field is > optional, and not included in the message it is still encoded on the > wire as a null string. > > Take a look at http://code.google.com/p/quickfast/wiki/FastFieldRules > > This, along with careful reading of the specification that you can find > at http://www.fixprotocol.org/fast should give you the information you > need to understand how the presence map bits are used by various > combinations of operator and presence attributes. > > Dale [You can unsubscribe from this discussion group by sending a message to mailto:[email protected]]
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