Hi Marty and Michael,
The operation attribute "notify-subscription-id" (OPTIONAL) in
Get-Notifications is SINGLE-VALUED. If you want to add an
(OPTIONAL) "notify-sequence-number" operation attribute, then
the accompanying "notify-subscription-id" MUST be specified,
Then this all hangs together nicely and avoids duplicate
harvesting of events which have been SUCCESSFULLY received
by the IPP Notification Receiver (remember the connection
might have broken just as the previous events were sent).
- Ira McDonald
I agree, but that means the client will have to send a list of
notify-subscription-id / notify-sequence-number pairs (although I realize
there would usually only be one).
Michael Sweet <firstname.lastname@example.org>@pwg.org on 07/27/2001 12:43:56 PM
Sent by: email@example.com
Subject: Re: IPP> Duplicate ippget events
Marty Joel wrote:
> Hi Michael,
> I agree with everything you've said.
> Actually, notify-sequence-number is what should be used by the client to
> ignore duplicates. For each subscription that matches its
> Get-Notifications (usually only 1 subscription), it needs to know that
> subscription ID and the last notify-sequence-number it received. That
> requires very little work on the part of the client.
Hmmm, from an implementation standpoint, it would be better if the
client could send the last sequence number is has received to the
server, so the server would only have to send events whose sequence
number is > the one provided. E.g., a client sends a server the
"notify-sequence-number" attribute in the Get-Notifications request,
and the server responds only with those events that have a higher
sequence number. This would also reduce the bandwidth used...
-- ______________________________________________________________________ Michael Sweet, Easy Software Products firstname.lastname@example.org Printing Software for UNIX http://www.easysw.com
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