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RE: A tricky matched values problem - I vote for (2)!!
You're right. I missed the "simple" in "simple filter".
Tom
> -----Original Message-----
> From: Bruce Greenblatt
> [mailto:bgreenblatt@directory-applications.com]
> Sent: Tuesday, October 19, 1999 1:38 AM
> To: Salter, Thomas A; d.w.chadwick@salford.ac.uk
> Cc: ietf-ldapext@netscape.com; osidirectory@az05.bull.com
> Subject: RE: A tricky matched values problem - I vote for (2)!!
>
>
> At 10:05 AM 10/18/99 -0400, Salter, Thomas A wrote:
> >I'm also voting for 2 for similar reasons.
> >
> >However, instead of a "search filter", I think it should
> just be a "SET of
> >AVA". Eliminating the filter should eliminate all
> ambiguity about which
> >filter items get evaluated. In X.500 this should be added to
> >EntryInformationSelection.
> >
>
> I don't think that the SET of AVA is sufficient for attribute value
> selection. AVAs in LDAP only allow you to specify the
> attribute type and a
> proposed value. They don't let you specify the relational
> operator. This
> is why I proposed the "Simple Filter" construct previously.
>
> Bruce
>
> > > -----Original Message-----
> > > From: Anthony Hodson [mailto:aeh@xdotd.demon.co.uk]
> > > Sent: Monday, October 18, 1999 6:10 AM
> > > To: d.w.chadwick@salford.ac.uk
> > > Cc: ietf-ldapext@netscape.com; osidirectory@az05.bull.com
> > > Subject: A tricky matched values problem - I vote for (2)!!
> > >
> > >
> > > Hi, David!
> > >
> > > Good to have your analysis, which I *generally* agree
> with. But ...
> > >
> > > With 1A, consider a filter OR(A, B) where, with a particular
> > > entry, both
> > > A and B are true; as a result of this (using 1A), assume
> that A would
> > > cause a value x to be returned, and that B would cause a
> > > value y to be
> > > returned.
> > >
> > > Presumably you would return both x and y with 1A, even
> > > though neither A
> > > nor B could be *completely* said to have contributed, since
> > > either could
> > > be omitted without affecting the outcome.
> > >
> > > It was consideration of this kind of issue that led to
> the simple and
> > > easy-to-implement rough-justice rule: if a filter item is
> > > TRUE, send the
> > > value anyway. I don't defend it at all on philosophical grounds.
> > >
> > > My view is that your solution 2 is *much* the better
> > > solution because of
> > > its direct approach to solving the problem, since
> matched-values was
> > > always a bit kloodgy for the reasons that you suggest. I
> > > think that it
> > > would be much better for FDAS/F.510, too. Something has to
> > > change with
> > > existing MVO implementations, and (2) presents no technical
> > > challenges.
> > >
> > > Best wishes
> > >
> > > Anthony
> > >
> > > In message <E11cz2q-00018p-00@rhenium.btinternet.com>,
> David Chadwick
> > > <d.w.chadwick@salford.ac.uk> writes
> > > >First let me apologise for taking so long to answer all the
> > > emails on this
> > > >topic, but I have been up to the proverbials in work (I
> > > still am, its now
> > > >10,30pm on Sunday evening).
> > > >
> > > >Firstly I do not believe that the Molesworth principle
> > > should apply for the
> > > >matched values control. This is because the user, in
> > > specifying this control,
> > > >is obviously trying to limit the size of the response,
> > > therefore the correct
> > > >action by the server would be the Molesless principle if
> > > there were one i.e. if
> > > >in doubt return less attribute values rather than more.
> > > >But I am not advocating either principle, but rather I am
> > > agreeing with Paul
> > > >Dale that sound logic and a consistent and easily reasoned
> > > scheme is needed.
> > > >And as Erik said "we need to be precise".
> > > >
> > > >Harald has rightly pointed out that quote "it might be
> > > better to have a control
> > > >that tells the server something about what the client wants
> > > back rather than
> > > >something about how he wants the search criteria treated."
> > > What matched values
> > > >was trying to do was both with one simple boolean. ie. the
> > > matched values
> > > >boolean was saying something about what the client wanted
> > > back (i.e. limit the
> > > >values), but using the search filter to specify precisely
> > > which values are to
> > > >be limited in the return. The trouble as we can see arose
> > > because the search
> > > >filter can be a mixture of truths, unknowns and falses,
> > > and a simple
> > > >matchedValuesOnly boolean was too blunt a tool (as
> > > currently specified) to
> > > >differentiate between them. It therefore was not precise
> > > enough in its
> > > >specification.
> > > >
> > > >Therefore it seems that there are two sensible options that
> > > can be taken:
> > > >
> > > >1) is to tighten up considerably on the definition of the
> > > current MVO boolean.
> > > >There are three views of how to tighten up the definition.
> > > 1A) One is to say
> > > >that only those attributes that contributed to the overall
> > > truth of the filter
> > > >are governed by the MVO boolean. 1B) Another is to say
> > > that if the filter item
> > > >was true then MVO applies to the attributes in the filter
> > > item (even if the
> > > >subfilter containing the filter item was false). 1C) And
> > > the final one
> > > >suggested by Bruce was if the attribute was in the filter,
> > > even if the filter
> > > >item was false, then apply MVO.
> > > >
> > > >2) the other is to replace the boolean by a return filter
> > > (as suggested by both
> > > >Harald and Bruce) that acts on the attributes to be
> > > returned and filters out
> > > >some of the values. This works independently of, and
> > > after, the Search filter.
> > > >
> > > >My preferred approach is the first, 1A) i.e.only those
> > > attributes that
> > > >contributed to the overall truth of the filter are governed
> > > by the MVO boolean.
> > > >My reasons are as follows:
> > > >
> > > >I reject the current X.500 text (option 1B) for the
> > > following reason:
> > > >subfilters that evaluate false or undefined might as well
> > > be missing from the
> > > >filter, and if they were there on their own then no entries
> > > would be returned.
> > > >THerefore they have no claim to act on the returned values
> > > of any entries.
> > > >
> > > >I reject option 1C) as it is too loose and it does not work
> > > properly for false
> > > >filter items, as presumably no attribute values would be
> > > returned from these
> > > >attributes.
> > > >
> > > >Option 2) has its merits, and is clean. The reason for
> > > rejecting it is
> > > >compatibility with X.500, and that option 1A can (as Mark
> > > points out) do the
> > > >same task anyway, but perhaps not quite as efficiently. So
> > > option 2) might be
> > > >more efficient than 1A) but at the expense of
> > > compatibility with existing
> > > >implementations.
> > > >
> > > >I am happy to update the ID was the proposed solution 1A
> > > unless anyone has
> > > >strong objections to this.
> > > > David
> > > >
> > > > ***************************************************
> > > >David Chadwick IS Institute, University of Salford, Salford
> > > M5 4WT Tel +44 161
> > > >295 5351 Fax +44 161 745 8169 Mobile +44 790 167 0359 Email
> > > >D.W.Chadwick@salford.ac.uk Home Page
> >http://www.salford.ac.uk/its024/chadwick.h
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> >
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> >
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> Bruce Greenblatt, Ph. D.
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