[SR-Users] Meaning of empty body in NOTIFY

[Daniel-Constantin Mierla]

Hello,

the notify is sent to inform about the state of the subscription, which 
is active in this case. If it would the first subscription to that user 
and force_active will not be set, then should be subscription state 
pending, iirc.

The empty body does not change anything to the phone information about 
the watched presentity, which was known to be offline.

Cheers,
Daniel

On 6/8/11 10:06 PM, Eugen Dedu wrote:
> No idea?
>
> On 05/06/11 22:31, Eugen Dedu wrote:
>> Hi,
>>
>> ekiga.net registrar uses kamailio 1.5.3 (yes, a bit old...) and for
>> users who are not registered an empty NOTIFY body is returned when asked
>> by a SUBSCRIBE. What does this mean from SIP standard point of view, and
>> from kamailio point of view (are they identical?) I see in 
>> RFC3265/3.1.6.2:
>> .... If the resource
>> has no meaningful state at the time that the SUBSCRIBE message is
>> processed, this NOTIFY message MAY contain an empty or neutral body
>> but is difficult for me to interpret what it means.
>>
>> Example: I ask the presence for a user xyz who registered and quit
>> application long time ago:
>>
>> SUBSCRIBE sip:xyz at ekiga.net SIP/2.0
>> CSeq: 1 SUBSCRIBE
>> Via: SIP/2.0/UDP
>> 82.238.108.175:5060;branch=z9hG4bKdabe824f-1a8e-e011-9efc-0024d693d8e8;rport 
>>
>>
>> User-Agent: Ekiga/3.3.1
>> From: <sip:eugen.dedu at ekiga.net>;tag=4888824f-1a8e-e011-9efc-0024d693d8e8
>> Call-ID: f602824f-1a8e-e011-9efc-0024d693d8e8 at snoopy
>> Supported: eventlist
>> To: <sip:xyz at ekiga.net>
>> Accept: application/pidf+xml
>> Accept: multipart/related
>> Accept: application/rlmi+xml
>> Contact: <sip:eugen.dedu at 82.238.108.175:5060>
>> Allow:
>> INVITE,ACK,OPTIONS,BYE,CANCEL,SUBSCRIBE,NOTIFY,REFER,MESSAGE,INFO,PING,PRACK 
>>
>>
>> Expires: 300
>> Event: presence
>> Content-Length: 0
>> Max-Forwards: 70
>>
>> I receive the following answer:
>>
>> NOTIFY sip:eugen.dedu at 82.238.108.175:5060 SIP/2.0
>> CSeq: 1 NOTIFY
>> Via: SIP/2.0/UDP 86.64.162.35;branch=z9hG4bK2a99.b8a72c47.0
>> User-Agent: Kamailio (1.5.3-notls (i386/linux))
>> From: sip:xyz at ekiga.net;tag=f85b0bd16aaafa8479586ac9f88b3198-10a0
>> Call-ID: f602824f-1a8e-e011-9efc-0024d693d8e8 at snoopy
>> To: sip:eugen.dedu at ekiga.net;tag=4888824f-1a8e-e011-9efc-0024d693d8e8
>> Contact: <sip:86.64.162.35:5060>
>> Subscription-State: active;expires=370
>> Event: presence
>> Content-Length: 0
>> Max-Forwards: 70
>>
>> To resume: What does SIP standard say about this NOTIFY with empty body?
>> Does this mean that the user xyz is offline?
>>
>> Or does this mean that user's status has not changed? In fact, the
>> NOTIFY with empty body (as shown above) is the first one sent by
>> kamailio, so there is no "previous" state of that user, hence
>> "unchanged" status has no meaning.
>>
>> Thank you,
>
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-- 
Daniel-Constantin Mierla
http://www.asipto.com