RE: [Sipping-tispan] Advice of Charge (AoC)

["Elwell, John" <[e-mail]>]

Anna,

Thanks, so the middle option (AOC-D) would tend to steer us in the direction
of SUBSCRIBE/NOTIFY rather than HTTP GET, because there can be multiple
notifications.

These three types of AOC are all session-related, yet there was some recent
discussion about AOC applied to other SIP messaging, not just
session-related. Can we assume that AOC is indeed limited to session-related
charges?

Some postings to this list have been discussing sending the charge
information in the context of the INVITE-initiated dialog for the session.
An intermediary would insert the charge information, and this then gives
rise to questions about security. What are the authentication requirements
for the charge information? Depending on requirements, insertion of this
information by a proxy may be problematic. A proxy can't insert a body. It
can insert a header, of course, but that header would not be covered by the
integrity protection that the Identity header provides. SUBSCRIBE/NOTIFY can
draw upon standard security measures much more easily than in-dialog
information.

John

> -----Original Message-----
> From: Martinez-Rebordosa, Anna 
> [mailto:[e-mail]] 
> Sent: 31 January 2006 09:25
> To: Elwell, John; [e-mail]; 
> [e-mail]; [e-mail]
> Cc: [e-mail]
> Subject: AW: [Sipping-tispan] Advice of Charge (AoC)
> 
> John,
> Aoc is defined on three types: 
> - AOC-S: served user received the information at the time of 
> establischment the session.
> - AOC-D: served user received the information during the 
> session. Every t seconds. t is a network operator option.
> -AOC-E: served user received the information at the end of 
> the session.
> 
> I hope this clarifies a little bit more.
> 
> Anna 
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: Elwell, John [mailto:[e-mail]] 
> Gesendet: Montag, 30. Januar 2006 22:29
> An: Michael Hammer (mhammer); GARCIN Sebastien RD-CORE-ISS; 
> Miguel Garcia
> Cc: [e-mail]
> Betreff: RE: [Sipping-tispan] Advice of Charge (AoC)
> 
> 
> Michael,
> 
> It seems to me that HTTP/GET would be a good choice if a 
> single immediate
> response can be expected. SUBSCRIBE/NOTIFY has some clear 
> benefits if there
> is likely to be a delay before the information is available (so the
> subscriber will receive a 2xx response and await a NOTIFY 
> request) or if the
> information might need to be updated during the subscription period
> (multiple NOTIFY requests). Can TISPAN people please clarify what is
> required?
> 
> John
> 
> > -----Original Message-----
> > From: Michael Hammer (mhammer) [mailto:[e-mail]] 
> > Sent: 30 January 2006 14:58
> > To: GARCIN Sebastien RD-CORE-ISS; Miguel Garcia
> > Cc: [e-mail]
> > Subject: RE: [Sipping-tispan] Advice of Charge (AoC)
> > 
> > All,
> > 
> > A comment from the peanut gallery.
> > 
> > I am concerned that precedents from a single media type 
> > service might unduly constrain a solution that uses multiple 
> > media types simultaneously, some of which could be 
> > session-oriented, some of which might be "connectionless".  
> > All this talk of piggy-backing and use of 183 does not seem 
> > to be generally useful in all situations.  
> > 
> > I would suggest that a solution that is general to all types 
> > of services and attempts to be as decoupled as possible from 
> > those services would minimize the possibility of feature 
> > interactions between AoC and other features/services.
> > 
> > That said, the essence of AoC is a request for information 
> > that seems to be a natural fit for a Subscribe/Notify type of 
> > operation for request and delivery.  A particular dialog or 
> > message will likely need to have an associated address from 
> > which this information can be requested.  One or more 
> > values/addresses can be added to message/INVITE to enable a 
> > UA to know where to send the Subscribe.  The accounting 
> > element will need to be able to identify the dialog or 
> > message and bind that to the charge or charge rate, which 
> > seems to be the nature of an Event package.
> > 
> > I suspect that AoC will not be the last type of "Event" that 
> > will be needed for SIP.  Leveraging a general mechanism would 
> > be better than reinventing event reporting for each of N 
> > "features" that will arise.  Talk of performance needs to 
> > keep a broad perspective on the overall system.
> > 
> > Mike
> > 
> > 
> > > -----Original Message-----
> > > From: [e-mail] 
> > > [mailto:[e-mail]] On Behalf Of GARCIN 
> > > Sebastien RD-CORE-ISS
> > > Sent: Monday, January 30, 2006 8:56 AM
> > > To: Miguel Garcia
> > > Cc: [e-mail]
> > > Subject: RE: [Sipping-tispan] Advice of Charge (AoC)
> > > 
> > > Miguel,
> > > 
> > > Please see answers below [SG]
> > > 
> > > Regards,
> > > sebastien 
> > > 
> > > -----Message d'origine-----
> > > De : Miguel Garcia [mailto:[e-mail]]
> > > Envoyé : lundi 30 janvier 2006 12:30
> > > À : GARCIN Sebastien RD-CORE-ISS
> > > Cc : [e-mail]
> > > Objet : Re: [Sipping-tispan] Advice of Charge (AoC)
> > > 
> > > Inline discussion.
> > > 
> > > GARCIN Sebastien RD-CORE-ISS wrote:
> > > > Miguel,
> > > > 
> > > > First it may be true that there has been some discussion in 
> > > the past about this but I think it is still interesting to 
> > > list the conclusions of those discussions in order for 
> > > readers (including me) to understand if there was indeed a 
> > > real problem with piggy-backing solution. Please note the 
> > > solution is not exaclty "piggy-backing" because in some flows 
> > > (e.g. AoC-S service) the AS generates the 183 answer and does 
> > > not wait for a 183 answer from the terminating side (see 
> > > figure 1/ WI3030).
> > > > 
> > > > Looking at your points: 
> > > >  
> > > > 1/ IMS Charging problem and creating artificial SIP message
> > > > ------------------------------------------------------------
> > > > I am not sure to undertand the problem. The AS is perfectly 
> > > entitled to create and send 183 answers downstream, such 
> > > message is needed anyway for the service and this has nothing 
> > > to do with "preconditions or sending charging information". 
> > > Could you please clarify ?
> > > 
> > > So here we go... the AS need to create artificial 183 
> > > messages when there might not be a need to send 183 at all. 
> > > Think for example that you call someone who happens to be an 
> > > automata, such as an answering machine, you will get 200 OK 
> > > immediately. This does not require a 183, but you need to 
> > > create it artificially and delay the session just for sending 
> > > the AoC information. It would be more natural to create a 
> > > separate side-by dialog for sending the required information.
> > > 
> > > [SG: Why is 183 more artificial than MESSAGE / INFO / or 
> > > anything else ? The 183 does not delay the session in my view 
> > > since it relies on a separate early dialog (as documented 
> > > currently in WI3030). 
> > > 
> > > Second: 183, as any other provisional responses, apply only 
> > > to INVITE transactions. So you would never be able to apply 
> > > the AoC service than any INVITE generated service, that is, 
> > > video, voice, and MSRP sessions.
> > > 
> > > [SG: I agree. The idea is that 183 would be used for AoC-S 
> > > (INVITE) in addition to INFO/BYE/200OK BYE in case of AoC-D 
> > > and AoC-E. If you need to send AoC for a non-INVITE 
> > > transaction (e.g. MESSAGE,PUBLISH...), you would use 200 OK 
> > > response to those transactions MESSAGE/PUBLISH to convey the 
> > > AoC information.]
> > > 
> > > 
> > > > 
> > > > 2/ Breaking end-to-end signalling
> > > > ---------------------------------
> > > > The AS does not break anything, it simply adds service 
> > > information to messages. This behaviour is very common in the 
> > > work we are doing in TISPAN.
> > > 
> > > If the 183 has to split the dialog between the calling and 
> > > the called party, it is breaking the end-to-end signalling. 
> > > While this situation can't be avoided in some cases, in 
> > > general it is desired to get away from it. It breaks any 
> > > possible end-to-end security, as a starting point. 
> > > 
> > > [SG: I agree with Christer's answer here.]
> > > 
> > > If the service can be implemented while the AoC AS behaves as 
> > > a proxy, that would be an advantage for the implementation of 
> > > the service and the future compatibility of services.
> > > 
> > > 
> > > BR,
> > > 
> > > 
> > > 
> > >      Miguel
> > > 
> > > > 
> > > > Regards
> > > > sebastien
> > > > 
> > > > 
> > > > 
> > > > -----Message d'origine-----
> > > > De : Miguel Garcia [mailto:[e-mail]]
> > > > Envoyé : lundi 30 janvier 2006 09:55
> > > > À : GARCIN Sebastien RD-CORE-ISS
> > > > Cc : [e-mail]
> > > > Objet : Re: [Sipping-tispan] Advice of Charge (AoC)
> > > > 
> > > > GARCIN Sebastien RD-CORE-ISS wrote:
> > > >> Hi Miguel
> > > >>
> > > >> First I have some problems with the service definition as 
> > > expressed in the draft-jesske-requirements-draft. The draft 
> > > seems to indicated the AoC service is always invoked by the 
> > > served user. Although this might be a valid case, this is not 
> > > the only way to invoke the service since it can be a 
> > > permantent invocation. I suggest that you copy and past the 
> > > service definition as documented by TISPAN in WI3030 instead 
> > > of the text at the beginning of §3.4.
> > > > 
> > > > 
> > > > True, there is a permanent service indication that does not 
> > > require any SIP signalling, thus, it does not have any 
> > > protocol impact. In the requirements we listed only those 
> > > which we believe they may have protocol impact.
> > > > 
> > > >> In other words the requirement "to signal to a network 
> > > that the service is invoked" is optional. Additionnal I 
> > > believe that it should be optional for the UA to indicate 
> > > whether it is capable of understanding an AoC information 
> > > sent by the network (note that this is different from 
> > > "invoking" the service). It is important that the 
> > > capabilities required from terminal is kept to a minimum so 
> > > as to make the AoC service possible for a wide range of terminals.
> > > > 
> > > > I agree.
> > > > 
> > > >> With regards to the delivery of the information, I don't 
> > > agree the piggy backing solution has been demonstrated as 
> > > "bad", in my view it is the most elegant way I have seen and 
> > > has the advantage to require minimum capability to terminals.
> > > > 
> > > > Here I disagree. I am aware of two contexts where 
> > piggyback has been
> > > > discussed: one is the IMS charging information, and you 
> > know what? 
> > > > When 3GPP wanted to remove the usage of preconditions, all 
> > > the problems where
> > > >   around the fact that "hmmmm... if we remove 
> > preconditions, there 
> > > > aren't enough messages to transport charging information, 
> > > so we can't 
> > > > remove preconditions". This is crap: creating artificial 
> > > SIP messages 
> > > > just to transfer required information.
> > > > 
> > > > The other context where this was discussed was in the 
> > > > Session-dependent policies. After some comparisons and 
> > > analysis, the 
> > > > SIP WG decided to create a sideby channel for providing 
> > > information of 
> > > > the policies (the slides were presented in an IETF meeting, 
> > > perhaps in 
> > > > Seoul, don't quite remember exactly).
> > > > 
> > > > Additionally, breaking the end-to-end signalling just 
> to provide 
> > > > sideby information is, in general, a bad idea. It should 
> > be avoided.
> > > > 
> > > > 
> > > >> Also I am surprised that you don't mention "MESSAGE" as 
> > > solution since you advocated this solution in TISPAN meeting ??
> > > >>
> > > > 
> > > > Yes, MESSAGE is also an alternative to transport the 
> > > information. So 
> > > > we have the SUB/NOT, REFER, and MESSAGE.
> > > > 
> > > >> Regards
> > > >> sebastien
> > > > 
> > > > BR;
> > > > 
> > > >      Miguel
> > > > 
> > > > 
> > > >>  
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>  
> > > >>
> > > >> -----Message d'origine-----
> > > >> De : [e-mail] 
> > > >> [mailto:[e-mail]] De la part de 
> > > Miguel Garcia 
> > > >> Envoyé : lundi 30 janvier 2006 08:41 À : 
> > '[e-mail]'
> > > >> Objet : [Sipping-tispan] Advice of Charge (AoC)
> > > >>
> > > >> Hi all in the list.
> > > >>
> > > >> I would like to get opinions on solutions for implementing 
> > > the Advice of Charge service.
> > > >>
> > > >> Requirements for this service are listed in the TISPAN 
> > > requirements I-D, Section 3.4:
> > > >> 
> > > 
> > 
> http://www.ietf.org/internet-drafts/draft-jesske-sipping-tispan-requi
> > > >> rements-02.txt
> > > >>
> > > >> When we discussed this service in Vancouver, Jonathan 
> > > suggested to take a look at the SIP Interaction Framework to 
> > > get ideas. They are very good ideas in the SIP Interaction 
> > > Framework, but still I would like to get opinions.
> > > >>
> > > >> This service presents two problems to be solved:
> > > >>
> > > >> 1) How to signal to a network node that the service is invoked
> > > >>
> > > >> 2) How to transport the required information to the User Agent.
> > > >>
> > > >>
> > > >> According to the interaction framework, invocation could 
> > > be signal by a combination of protocol elements, 
> > > specifically: Allow REFER, Accept-Types with some specific 
> > > XML format, Contact with schemes: http, Contact with GRUU, 
> > > Supported with "tdialog", ... don't know what else.
> > > >>
> > > >> While that is valid, I think it presents three problems. 
> > > First, it is not possible to distinguish between "this is 
> > > what the UA supports" from "this is the invocation to the 
> > > service". Second. it makes the configuration of the initial 
> > > filter criteria (to trigger to the AoC Application server) a 
> > > nightmare, because instead of searching for one "item", we 
> > > need to create comparisons for four or five items. Third, 
> > > this works as long as there is some unique item to the 
> > > service, which could be the type of body declared in the 
> > > Accept-Types, but as soon as we wanted to reuse this body for 
> > > some other service, we would run into trouble.
> > > >>
> > > >> One proposal to invoke the service was to define a new 
> > > specific header, let's call it P-AoC, that contains some 
> > > parameters that define the service behavior. For example, it 
> > > could contain some preference of the reporting time or 
> > > something like that. Another alternative could be to use a 
> > > subscription to an event package, in which case, we are 
> > > determining not to use a REFER to an HTTP URI for conveying 
> > > the information. A third possibility is to define a specific 
> > > feature tag, but I think this isn't really a feature, but a 
> > > whole service.
> > > >>
> > > >> On the delivery of information, we can think of a REFER to 
> > > an HTTP URI or a SUB/NOT type of notification. Some folks 
> > > have been thinking of piggy-backing the information to SIP 
> > > requests or responses that "happens to pass by", but this 
> > > solution is bad, as it has been demonstrated with the 
> > > charging stuff in IMS, besides it does not meet the 
> > > requirement of delivering information "a few seconds after 
> > > the communication has ended" 
> > > >> (REQ-AoC-1). So I guess the choices are just REFER + HTTP 
> > > URI or SUB/NOT.
> > > >>
> > > >> I am willing to hear comments that can provide the needed 
> > > guidance to TISPAN.
> > > >>
> > > >> Best regards,
> > > >>
> > > >>            Miguel
> > > >>
> > > > 
> > > 
> > > -- 
> > > Miguel A. Garcia           tel:[phone]
> > > sip:[e-mail]
> > > Nokia Research Center      Helsinki, Finland
> > > 
> > > 
> > > _______________________________________________
> > > Sipping-tispan mailing list
> > > [e-mail]
> > > https://www1.ietf.org/mailman/listinfo/sipping-tispan
> > > 
> > 
> > _______________________________________________
> > Sipping-tispan mailing list
> > [e-mail]
> > https://www1.ietf.org/mailman/listinfo/sipping-tispan
> > 
> 
> _______________________________________________
> Sipping-tispan mailing list
> [e-mail]
> https://www1.ietf.org/mailman/listinfo/sipping-tispan
> 

_______________________________________________
Sipping-tispan mailing list
[e-mail]
https://www1.ietf.org/mailman/listinfo/sipping-tispan