[sr-dev] RLS/PUA concurrency issue

Andrew Miller andrew.miller at crocodile-rcs.com
Thu Aug 11 09:42:37 CEST 2011


Klaus,

Sorry we should have mentioned that we did investigate this option, 
however we do not think it will work.

I may have got the details below wrong, as Peter has been looking at 
this, however the reason is something like the following:

The main job of the 200 handler is to write a database entry that binds 
the incoming RLS subscription to the back-end presence subscription. A 
pointer to the RLS subscription is bound to the INVITE transaction, and 
is therefore available to the 200 call back function. The same 
information is not available to the NOTIFY handler - it expects to get 
this information FROM the database. Therefore, we cannot (unfortunately) 
handle the NOTIFY in exactly the same way as the 200.

Is that right Peter?

Andy


On 11/08/2011 08:30, Klaus Darilion wrote:
>
> Am 10.08.2011 18:54, schrieb Daniel-Constantin Mierla:
>> Hello,
>>
>> I would like to look closer at the issue and figure out possible
>> solution, but I am traveling for time being, so just quick thoughts.
>>
>> One approach would the similar solution as for the fast CANCEL (which
>> gets to the server before the INVITE). What we do (in config), we check
>> if there is an INVITE transaction for the CANCEL and if not we just drop
>> the CANCEL (no reply). That will force the UA to do retransmissions,
>> which eventually will come after the INVITE is received/processed.
> Does not work with TCP requests.
>
>> The second idea would be to have a pending queue, keep the NOTIFY for a
>> while there and when 200ok is coming, look in the queue if it is
>> something for respective dialog. If no dialog is created after a while,
>> request that are older in the queue will be just discarded.
> The NOTIFY is in an implicit 200 OK. So if there is an ongoing SUBSCRIBE
> transaction which matches the NOTIFY, the NOTIFY should trigger the same
> actions as the 200 OK. The later arriving 200 OK can then be ignored.
>
> regards
> klaus
>
>> Cheers,
>> Daniel
>>
>> On 8/10/11 6:19 PM, Andrew Miller wrote:
>>> Sorry Pete,
>>>
>>> That seems to make things better, but does not solve the issue for me.
>>>
>>> Most times this now clean when a client logs in, but about 1 in 10 I
>>> am still getting an error message. In one case I had 9 error messages
>>> on one log-in.
>>>
>>> Andy.
>>>
>>> On 10/08/2011 15:58, Peter Dunkley wrote:
>>>> I've been playing around with this here and making presence and rls
>>>> use TCP instead of UDP seems to help with this problem.  Presumably
>>>> this is because using TCP enforces in-order delivery of messages.
>>>>
>>>> To make presence and rls use TCP I:
>>>>
>>>>    * Added a ;transport=tcp parameter to the SIP URI I had set for
>>>>      presence server_address
>>>>    * Added a ;transport=tcp parameter to the SIP URI I had set for rls
>>>>      server_address
>>>>    * Set the rls outbound_proxy parameter to
>>>>      "sip:127.0.0.1;transport=tcp"
>>>>
>>>>
>>>> It's not a proper fix, but I think it works around the issue.
>>>>
>>>> Regards,
>>>>
>>>> Peter
>>>>
>>>> On Mon, 2011-08-01 at 13:40 +0200, Klaus Darilion wrote:
>>>>> Am 01.08.2011 12:28, schrieb Andrew Miller:
>>>>>> I attempted to insert a dialog entry in the hash table on sending the
>>>>>> SUBSCRIBE, unfortunately this did not cure the problem
>>>>>>
>>>>>> Has anyone any suggestions for the cleanest and easiest method to ensure
>>>>>> that the 200 is handled before the NOTIFY?
>>>>> The cleanest solution would be to establish the dialog when the NOTIFY
>>>>> is received although the 200 OK is missing.
>>>>>
>>>>> The NOTIFY can be seen as an implicit 200 OK.
>>>>>
>>>>> regards
>>>>> Klaus
>>>>>
>>>>> _______________________________________________
>>>>> sr-dev mailing list
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>>>> -- 
>>>> Peter Dunkley
>>>> Technical Director
>>>> Crocodile RCS Ltd
>>>>
>>>>
>>>>
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>>>
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>> -- 
>> Daniel-Constantin Mierla -- http://www.asipto.com
>> Kamailio Advanced Training, Oct 10-13, Berlin: http://asipto.com/u/kat
>> http://linkedin.com/in/miconda -- http://twitter.com/miconda
>>
>>
>>
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