[SR-Users] AVPOPS / TM behavior

[Klaus Darilion]

The description is implicit: "AVPs are special variables that are 
attached to SIP transactions." As a spiral causes 2 transactions there 
are two different contexts for AVPs.

Feel free to improve/extend the description.

regards
Klaus

On 07.08.2012 21:49, Brandon Armstead wrote:
> Klaus,
>
>     I see the following:
>
> AVPs are special variables that are attached to SIP transactions. It is
> a list of pairs (name,value). Before the transaction is created, the AVP
> list is attached to SIP request. Note that the AVP list works like a
> stack, last added value is retrieved first, and there can be many values
> for same AVP name, an assignment to the same AVP name does not overwrite
> old value, it will add the new value in the list.
>
> While this does *technically* describe the behavior - we may want to
> explicitly point out this behavior when spiraling to the same proxy.  I
> guess to me its not clear enough based off of this above copied text.
>   Unless I am still missing the explanation somewhere else in the text?
>   Thanks!
>
> Sincerely,
> Brandon Armstead
> On Tue, Aug 7, 2012 at 12:00 PM, Klaus Darilion
> <klaus.mailinglists at pernau.at <mailto:klaus.mailinglists at pernau.at>> wrote:
>
>     Once you know it you will find it :-)
>
>     http://www.kamailio.org/wiki/__cookbooks/3.3.x/__pseudovariables#avps <http://www.kamailio.org/wiki/cookbooks/3.3.x/pseudovariables#avps>
>
>     regards
>     Klaus
>
>
>     On 07.08.2012 18:22, Brandon Armstead wrote:
>
>         Klaus,
>
>              Thank you for this detailed explanation.  This is
>         essentially what I
>         figured was happening.  I was able to use htable to work around it.
>
>         I guess however I am still confused as to where there is any public
>         documentation on this specific bit.  Had I've not been working with
>         Kamailio for years I would think this would confuse others.
>
>         Let me know if it is somewhere else, otherwise I will add it to the
>         Kamailio wiki.
>
>         Sincerely,
>         Brandon Armstead
>
>         On Tue, Aug 7, 2012 at 2:32 AM, Klaus Darilion
>         <klaus.mailinglists at pernau.at
>         <mailto:klaus.mailinglists at pernau.at>
>         <mailto:klaus.mailinglists at __pernau.at
>         <mailto:klaus.mailinglists at pernau.at>>> wrote:
>
>              AVPs are associated with the transaction. If you "spiral" a
>         request
>              through the same proxy, then for the proxy it is a new
>         transaction.
>              Thus, when processing the request a second time, there is a new
>              transaction and you do not have access to the AVPs of the
>         previous
>              transaction.
>
>              Workarounds are:
>              - store data in SIP headers and retrieve it later (ugly)
>              - use htable module to store data during transaction 1 and
>         retrieve
>              it during transaction 2. Therefore you need a known "key"
>         which is
>              identical in this 2 transactions only (e.g. use "$ci$ft" as
>         base for
>              the key).
>
>              regards
>              Klaus
>
>
>
>
>
>              On 07.08.2012 00:27, Brandon Armstead wrote:
>
>                  Hello,
>
>                       I am curious if there is any documentation on how
>         AVP's
>                  processing
>                  works in the following scenario below.
>
>                  UAC 1 -> KAMAILIO -> KAMAILIO -> DEST
>
>                  It seems that AVP's I set between UAC 1 -> KAMAILIO are
>         lost once I
>                  relay back to the same KAMAILIO proxy (self)?
>
>                  Is there any documentation on why or when this would occur?
>
>                  Is there a better way to handle such a scenario?  i.e.
>         more dynamic
>                  internal routing, vs relaying to self.
>
>                  Thanks as always in advance!
>
>                  Sincerely,
>                  Brandon Armstead
>
>
>                  ___________________________________________________
>
>                  SIP Express Router (SER) and Kamailio (OpenSER) - sr-users
>                  mailing list
>         sr-users at lists.sip-router.org
>         <mailto:sr-users at lists.sip-router.org>
>         <mailto:sr-users at lists.sip-__router.org
>         <mailto:sr-users at lists.sip-router.org>>
>         http://lists.sip-router.org/____cgi-bin/mailman/listinfo/sr-____users
>         <http://lists.sip-router.org/__cgi-bin/mailman/listinfo/sr-__users>
>         <http://lists.sip-router.org/__cgi-bin/mailman/listinfo/sr-__users
>         <http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users>>
>
>
>