Subject: [Fwd: Re: matched values 05]

From: David Chadwick <[email-masked]>
Date: Sat, 23 Dec 2000 23:27:49 -0800

Bruce Greenblatt wrote:
> 
> It appears to me that there is the possibility that the search results will
> come back in a different order depending on how the MVO and sort controls
> are processed.  Section 4 states: "This control acts independently of other
> LDAP controls such as server side sorting".  To me if the controls were
> independent, I would get exactly the same data back in exactly the same
> order.  So, I don't think that MVO and the sort control are "independent".
> 

Bruce,

OK, now I understand your problem. "acts independently" is the wrong
phrase to use. Note that section 4 does state

 However, there might be 
interactions between this control and other controls so that a 
different set of Search Result Entries are returned, or the entries 
are returned in a different order, depending upon the sequencing of 
this control and other controls in the LDAP request. 

Therefore how about this for a rewording

Whilst this control is applied independently of other controls, there
might be interactions between etc.

> Note that RFC 2891 requires the following processing method for
> multi-valued attributes: when an entry happens to have multiple values for
> that attribute and no other controls are present that affect the sorting
> order, then the server SHOULD use the least value (according to the
> ORDERING rule for that attribute).
> 
> So, I would require the MVO to be processed BEFORE the sort
> control.  Otherwise, the sorted entries may turn out to be no longer sorted.

Clause 4 does state

For these reasons it is recommended that the ValuesReturnFilter 
control in a SearchRequest SHOULD precede other controls that affect 
the number and ordering of SearchResultEntrys.

However what you are suggesting is that the server processing of
controls acts independently of the ordering of the controls in the
request. One could argue that this is not right, that the user decides
the ordering of the controls when he/she places them in the request and
the server must obey this ordering. This is the principle adopted in the
MVO ID. I dont feel strongly either way about which principle is adopted
(but would tend towards user control if I were forced to choose), but
this is not an MVO issue. It is an LDAP controls issue that needs to be
decided at a much higher level than in an individual ID, as it will
affect ALL control extensions to LDAP. Therefore is this an issue that
LDAPBIS should decide (or have they already decided it??)

David

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David Chadwick, BSc PhD
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