[OpenSER-Users] Out of order notifications

Leonard Broman firepiper at gmail.com
Wed Feb 27 20:14:48 CET 2008


Hi!

I have integrated OpenSER as a dedicated presence server in an ims
network and I'm somewhat suffering from the delays the traversal of
the ims core causes. Here's whats happening:
Upon subscription the presence module sends a 202 Accepted (actually
named OK, cosmetic bug?). At almost the same instant it also sends the
first, in-dialog notify.
What happens later is that sometimes the notify arrives before the ok.
When this happens the client (on top of jain-sip) cannot identify the
subscription dialog for the notification. It does not treat it
correctly and does not respond OK to it. The absence of the response
results in a timeout and the presence server invalidates the
subscription.

Now, to solve this issue, would it be wise to introduce a parameter in
the presence module which delays to transmission of the first
notification to ease up the situation for the client.

Another solution is of course that the client simply inspects the
local tag to prematurely identify the upcoming sip dialog for the
subscription and then be able to treat the request properly. However,
how does this stand against the standards?

I would be grateful for your input on the subject.

Leonard Broman




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