RE: [bt-spec] BTP Issue 20 : Resending PREPARE

[Peter Furniss <peter.furniss@choreology.com>]

 

BTP Issue 20 : Resending PREPARE

Category: minor technical
Submitter: Gordon Hamilton, AppliedTheory
Reference: Page 52
Current text: If PREPARED has not been received from any Inferiors in the confirm-set, PREPARE shall be issued to them. ????
Question: Even if PREPARE has been sent already?

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It would not be an error to send PREPARE again - the state sequence will cope with that. In fact, if the Supeiror has reason to believe or fear that the earlier PREPARE got lost (re-awakened/reconnected after outage, local timeout, received inferior_status), then it should resend the PREPARE (which is why the state table can cope)

 

I suggest a note at this point:

 

However, the sentence quoted is slightly ambiguous in the case where some, but not all, Inferiors have spontaneously prepared-.

 

Suggested text - replace and add:

 

If, for each of the Inferiors in the confirm-set, PREPARE has not been sent and PREPARED has not been received, PREPARE shall be issued to that Infeiror.

 

NOTE --   If PREPARE has been sent but PREPARED not yet received from an Infeiror in the confirm-set, it is an implementation option whether and when to re-send PREPARE. The Supeiror implementation may choose to re-send PREPARE if there are indications that the earlier PREPARE was not delivered.