Subject: Sv: A tricky matched values problem

From: "Erik Andersen" <[email-masked]>
Date: Wed, 29 Sep 1999 15:22:34 +0200

A tricky question. I believe the problem comes from the ambiguity of the word "contribute".

We can either understand "contribute" to mean 

1) that a non-negated filter item matches a value of the attribute and therefore only the matched value should be returned. 

2) that for an attribute value to contribute, it is not only required that a non-negated filter item matches the value, but this filter item shall also be a part of a subfilter that evaluates to TRUE  (for definition of subfilter, see the current X.500 extension work to fulfil ITU-T F.510 requirements).

If we take the first interpretation,  the value [email-masked] will contribute.

Taking the second interpretation and by looking at the filter, we easily see that it consists of two subfilters:

AND(mail=[email-masked])(telephoneNumber=47)
AND(cn=Sean*)

and the value [email-masked] will not contribute.

The question is what the user expect when setting this search control (a user would not or should not be required to understand the tricky difference between the two interpretation). I have a feeling that an ignorant user will assume the first interpretation and will not understand the fine point about subfilters.

Whatever we do, we have to be precise. It will also affect our text for family of entries. 

Kind regards, Erik Andersen

-----Oprindelig meddelelse-----
Fra: David Chadwick <[email-masked]>
Til: [email-masked] <[email-masked]>; [email-masked] <[email-masked]>
Dato: 29. september 1999 13:45
Emne: A tricky matched values problem

Thomas Salter providing the following filter:

(OR(AND(mail=[email-masked])(telephoneNumber=47))(cn=
Sean*))

to an entry containing the following attributes.

cn: Sean Mullan
mail: [email-masked]
mail: [email-masked]
telephoneNumber: +1 781 442 0926
telephoneNumber: 555-9999

As you can see, the overall filter is true, the AND is false, but the 
mail attribute value matches true. The question is "does matched 
ValuesOnly apply to the mail attribute or not". ie. should one or two 
mail attribute values be returned.

On the FOR side (one returned value), we have that the AVA was 
true,
On the AGAINST side, we have that the AVA did not contribute to 
the overall filter matching true.

My first reaction was to say that only one mail value should be 
returned, but whilst drafting the proposed textual addition to X.500 I 
have started to change my mind. 

What does anyone else think.

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 [email-masked]
Home Page  http://www.salford.ac.uk/its024/chadwick.htm
Understanding X.500  http://www.salford.ac.uk/its024/X500.htm
X.500/LDAP Seminars http://www.salford.ac.uk/its024/seminars.htm
Entrust key validation string MLJ9-DU5T-HV8J

***************************************************

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From: Bruce Greenblatt <[email-masked]>
Date: Wed, 29 Sep 1999 09:02:09 -0700

I don't much care for the matched values control, but I'd prefer a third
(looser) interpretation.

3)  If the attribute is mentioned in the filter then return it.  If the
client weren't interested in the attribute-value, then it wouldn't have
included it in the filter.  I think that this interpretation will be
substantially simpler to implement, especially given the fact the complex
filter evaluation can normally be short circuited in certain scenarios.
Either of the two interpretations below may have a substantial performance
impact...

Bruce

At 03:22 PM 9/29/99 +0200, Erik Andersen wrote:
>1) that a non-negated filter item matches a value of the attribute and
therefore only the matched value should be returned. 
>
>2) that for an attribute value to contribute, it is not only required that
a non-negated filter item matches the value, but this filter item shall
also be a part of a subfilter that evaluates to TRUE  (for definition of
subfilter, see the current X.500 extension work to fulfil ITU-T F.510
requirements).
>The question is what the user expect when setting this search control (a
user would not or should not be required to understand the tricky
difference between the two interpretation). I have a feeling that an
ignorant user will assume the first interpretation and will not understand
the fine point about subfilters.
>Til: [email-masked] <[email-masked]>;
[email-masked] <[email-masked]>
>What does anyone else think.
==============================================
Bruce Greenblatt, Ph. D.
Directory Tools and Application Services, Inc.
http://www.directory-applications.com