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But in this case
it is an implementation construct that makes contradiction avoidance
possible at all. This text is only in a note to advise on how what is
going on, and I fear we are begging more explanation that is justified - we
should now explain "synchronously", since it's not used anywhere else, and
has to refer the sequence of sending CONFIRM to the remaining Inferiors -
and even that there is a sequence (otherwise "first ... participant" doesn't
have meaning). And if the coordinator also has other resources that
are not connected via BTP (such as local resources), they must not have been
told to confirm or commit (or there is some way of undoing them). And
this has got to be the top of the confirm tree, so it can change its mind.
This sort of stuff is ok to do in an implementation when you are sure
exactly what is going on, but I think it muddies the point of the sentence
in the first place to explain when contradiction can be avoided.
I'd rather remove the "latter will cause a CONTRADICTION" sentence than have
to put in 8 times the text to explain the
exception.
I disagree. At the end of the day a specification is no
use if it cannot be implemented, and providing hints to assist such
implementations is something we should be doing.
Mark.
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Dr.
Mark Little
Transactions Architect, HP Arjuna Labs
Email: mark@arjuna.com | mark_little@hp.com
Phone: +44 191
2064538
Fax : +44 191 2064203
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