[This message was posted by Rolf Andersson of Pantor Engineering <[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/63b9771e - PLEASE DO NOT REPLY BY MAIL.]
Hi, 0xC0 means that the only bit set is the first bit. This is indeed the presence bit for template id. The first field in the template is mandatory and has no operator so it doesn't have a pmap entry and should always be present on the wire. The second field is optional but it has no operator so it doesn't have a pmap entry either and should always be present on the wire. An absent optional value is represented by a NULL that is encoded as a special value on the wire. Please refer to the specification section 10.6.3, esp the table at the end of the section. So, in summary, you should see three SBIT-encoded fields following the pmap. HTH, Rolf > Hi, > > I am trying to understand the presence map better. > > When I connect to my provider, the first byte I received is 0xC0, which > is the presence map. > > The first bit after the stop bit is 1 (0xC0=11000000), indicating the > template ID exists. > > And it does exist right after this byte (presence map). > > My question is -- does 0xC0 here indicate that none of the fields in > that specific template exists (since the remaining bits are zeros in the > presence map)? > > However, the template has only 2 fields and 1 of them is mandatory: > <string name="Sender" id="10000"></string> <string name="VendorID" > presence="optional" id="10001"></string> > > Am I missing something? > > Thanks in advance! [You can unsubscribe from this discussion group by sending a message to mailto:[email protected]]
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