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

[Tom Taylor <[e-mail]>]

You should now be using RFC 3525 as the equivalent to H.248.1 version 1.

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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