Subject: RE: [Simple] about Cseq sequence numbers

From: [email-masked]
Date: Wed, 6 Mar 2002 12:54:43 +0200

The SUBSCRIBE CSeq and NOTIFY CSeq are independent.

Your Subscription refresh carried a Cseq of 2. The NOTIFY following that should carry a Cseq of 5. When receiving a NOTIFY, all you do is update the Dialog state with the new remote Cseq.

Regards,
Hisham

> -----Original Message-----
> From: ext Lamine Brahimi [mailto:[email-masked]]
> Sent: Wednesday, March 06, 2002 12:07 PM
> To: [email-masked]
> Subject: [Simple] about Cseq sequence numbers
> 
> 
> 
> Dear all,
> 
> Suppose a watcher subscribes to a presentity presence info with
> an initial SUBSCRIBE msg  with a Cseq value of 1.
> the watcher receives the corresponding NOTIFY  with a Cseq 
> value of 1 (the
> same).
> Then the presentity updates several times its presence info 
> and the watcher
> receives several NOTIFY with incremented Cseq values. (ie if 
> the presence
> info changed twice
> the last NOTIFY has a Cseq value of 3, right ?).
> Then when the watcher wants to refresh its subscription I do that:
> it sends a SUBSCRIBE with a CSeq value of 2 and a matching 
> Dialog To tag.
>  It receives its corresponding NOTIFY with a CSeq value of 2.
> So my (little) problem is that I have two transactions which 
> have the same
> Cseq number of 2 in the same dialog :
> the latest NOTIFY and the first one notifying an update in Presentity
> presence info.
> Is it correct like that ?
> A possible solution to avoid that is to set the Cseq value of the
> refreshing SUBSCRIBE to a value one
> higher than the latest NOTIFY received in that dialog (in our 
> case 4, if
> presence info changed twice before the refresh)
> and not the latest SUBSCRIBE sent.
> 
> Does someone knows what to do ?
> Thanks,
> Lamine.
> 
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