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

[Micael Karlberg <[e-mail]>]

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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