Hi,
i think that establishstatus+checkin command would be great … if they would not depend on "everything will be always OK" expectation 
What am I trying to say: if I successfuly call "checkin" and anything bad (computer crash, database error, out of memory, …) happens before I parse XML response and act accordingly to it (eg. save it to database etc.), I have a problem:
- C2 thinks that I have successfuly "checked in" and will not send me lost info next time
- my server has to call "establishstatus" again when it detects any error … IF it detects that there was an error.
It would be nice to have some sort of acknowledgement protocol so as "checking" would then always return all informations since last ACK and not _since last checkin. So instead of current sequence "establishatstus, checkin, checkin, checkin, …" it would look as "establishstatus, checkin, ack, checkin, ack".
