Re: [Megaco] Ambiguous definition of auditReturnParameter in v2 ABNF

[Christian Groves <[e-mail]>]

Hello Troy and Micael,

I agree with Troy 6.3 the syntax does fix the problem in both empty and 
non-empty cases. We want to change the heading to make this clear.

The other problem which has be highlighted now by several people to me is the 
fact the IG seems to be for H.248.1v1 only. This is NOT the case. It is for both 
V1 and V2. If a change is for V1 or V2 only then this is mentioned (see 6.9 & 
6.10). I've already prepared a contribution for the September SG16 meeting to 
clear this confusion up.

The IETF draft/RFC do not contain any IG additions nor do the published ITU 
documents.

Regards, Christian

Micael Karlberg wrote:
> Hi,
> 
> I made the changes described by Troy:
> 
>     auditReturnParameter = ( mediaDescriptor / modemDescriptor /
>                              muxDescriptor / eventsDescriptor /
>                              signalsDescriptor / digitMapDescriptor /
>                              observedEventsDescriptor /
>                              eventBufferDescriptor /
>                              statisticsDescriptor / packagesDescriptor /
>                              errorDescriptor / auditReturnItem)
>  
>     auditReturnItem = ( MuxToken / ModemToken / MediaToken /
>                         DigitMapToken / StatsToken /
>                         ObservedEventsToken / PackagesToken )
> 
>     auditItem = ( auditReturnItem / SignalsToken /
>                   EventBufferToken / EventsToken /
>                   indAudterminationAudit )
> 
> This seems to work just fine, and since it is the way it's done
> in the IG (h248s-ig) why not use this construction in version 2?
> 
> By the way. I have been using the draft-ietf-megaco-3015corr-03.txt
> document assuming it to be up-to-date with the latest IG. It was only 
> when Troy pointed out the auditReturnItem that I realized that something
> was not right. h248s-ig.pdf is dated 25 October 2002 and 
> draft-ietf-megaco-3015corr-03.txt is dated December 2002 (i.e. later). 
> Is there a later version of the draft-ietf-megaco-3015corr document
> or is it dead (it did expire June 2003)?
> 
> Regards,
> 	/BMK
> 
> Troy Cauble writes:
>  > Christian Groves wrote:
>  > 
>  > 
>  > >>
>  > >>  >  > So as has been mentioned by Tom we need to fix this. So how 
>  > >> about we delete  > audititem from? It removes the ambiguity.
>  > >>  > auditReturnParameter = (mediaDescriptor / modemDescriptor /
>  > >>  >                          muxDescriptor / eventsDescriptor /
>  > >>  >                          signalsDescriptor / digitMapDescriptor /
>  > >>  >                        observedEventsDescriptor / 
>  > >> eventBufferDescriptor /
>  > >>  >                          statisticsDescriptor / packagesDescriptor /
>  > >>  >                           errorDescriptor / auditItem)
>  > >>  >  > and restore this to v1.
>  > >>
>  > >> Delete auditItem from auditReturnParameter? But auditItem was part of 
>  > >> auditReturnParameter even in v1. 
>  > > 
>  > > 
>  > > [CHG] Yes, must have been looking at an old version of v1.
>  > > 
>  > >>
>  > >>
>  > >>  > The individual auditing mechanism was only meant to change the 
>  > >> request  > mechanisn not what was returned as the "usual" audit reply 
>  > >>  > should have been enough to send the data back that you need. Does 
>  > >> this  > solve the problem. If not, Micael as you need unambiguous 
>  > >> syntax can you  > propose a simple ABNF fix that would solve your 
>  > >> problem/s?
>  > >>
>  > >>
>  > >> I really hope that I am not the only one who is writing a version 2
>  > >> parser, or else I am wasting my time (or are about to strike gold :)
>  > >>
>  > >> As for a solution, how about adding a token and changing the 
>  > >> definition of indAudterminationAudit to:
>  > >>
>  > >> indAudterminationAudit = IndAudTerminationAuditToken 
>  > >>                          indAudauditReturnParameter  
>  > >>                          *(COMMA indAudauditReturnParameter)         
>  > >> Not pretty, but it should do the trick. I have not tested it
>  > >> with real messages, but atleast my parser generator did not complain 
>  > >> anymore.
>  > > 
>  > > 
>  > > [CHG] I think the point is that the MGC shouldn't be concerned whether 
>  > > the audited parameter is from a descriptor audit or an individual audit. 
>  > > The syntax provided for a descriptor audit is enough to return an 
>  > > individual audit. The problem lies that AuditItem is used both in the 
>  > > command request and reply ABNF. I was thinking about a token yesterday 
>  > > myself but when I had a look at the ASN1 and saw that it used existing 
>  > > AuditDescriptor reply syntax I thought we shouldn't allow using the 
>  > > IndAudRep.
>  > > Would a rule that,
>  > > 
>  > > ; For audit replys the indAudterminationAudit SHALL not be used.
>  > > auditItem            = ( MuxToken / ModemToken / MediaToken /
>  > >                         SignalsToken / EventBufferToken /
>  > >                         DigitMapToken / StatsToken / EventsToken /
>  > >                         ObservedEventsToken / PackagesToken ) /
>  > >                         indAudterminationAudit)
>  > > 
>  > > Be a solution?
>  > > 
>  > > Regards, Christian
>  > 
>  > IG item 6.3 fixed the related conflicts for V1.  It's not clear if being
>  > in the IG means it applies to V2 as well.
>  > 
>  > I think 6.3 should be explicitly applied to V2 because
>  > 1) it makes the two versions more alike, and
>  > 2) it fixes the conflicts.
>  > 
>  > 
>  > IG item #6.3 (http://www.itu.int/itudoc/itu-t/com16/implgd/h248s-ig.pdf)
>  > 
>  >    auditReturnParameter = (mediaDescriptor / modemDescriptor /
>  > 			muxDescriptor / eventsDescriptor /
>  > 			signalsDescriptor / digitMapDescriptor /
>  > 			observedEventsDescriptor /
>  > 			eventBufferDescriptor /
>  > 			statisticsDescriptor / packagesDescriptor /
>  > 			errorDescriptor / auditReturnItem)
>  > 
>  >    auditReturnItem = (MuxToken / ModemToken / MediaToken /
>  > 			DigitMapToken / StatsToken /
>  > 			ObservedEventsToken / PackagesToken )
>  > 
>  >    ;at-most-once, and DigitMapToken and PackagesToken are not allowed
>  >    ;in AuditCapabilities command
>  >    auditItem = ( auditReturnItem / SignalsToken /
>  > 			EventBufferToken / EventsToken )
>  > 
>  > 
>  > Note that indAudterminationAudit was not in V1.  It must be added to
>  > auditItem.  I think Christian is arguing that those resulting token
>  > conflicts are not critical, because the indAud variations are always
>  > followed by "{" or "=", which can distinguish them from the individual
>  > tokens of an auditItem.  So no other changes are necessary.
>  > 
>  > -troy
>  > 
>  > 
>  > 
> 
> 
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