[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
Re: RFC 2596 questions
Date forwarded: Fri, 20 Oct 2000 09:57:30 -0700 (PDT)
Date sent: Fri, 20 Oct 2000 10:56:01 -0600
From: "Jim Sermersheim" <JIMSE@novell.com>
To: <d.w.chadwick@salford.ac.uk>
Copies to: <Mark.Wahl@innosoft.com>, <ietf-ldapext@netscape.com>
Subject: Re: RFC 2596 questions
Forwarded by: ietf-ldapext@netscape.com
> Getting back to this:
>
> The example David gives below shows a subtype inheriting from multiple
> supertypes. As of yet, I believe that this is illegal in X.500/LDAP
It might be illegal in LDAP but it is not illegal in X.501.
> and as such might cause problems with existing servers.
>
> I don't have a good feeling of closure on this subject. We need to
> revise 4.1.5 of RFC 2251 to say one of the following:
>From the 3 options I prefer option 3 from a modelling perspective,
but pragmatically what are the implementation implications of the 3
different models (not being a server implementer myself)?
David
>
> 1) "An AttributeDescription with one or more options is treated as a
> direct subtype of the attribute type without any options" (inserted
> direct)
>
> or
>
> 2) "An AttributeDescription with one option is treated as a direct
> subtype of the attribute type without any options. An
> AttributeDescription with more than one option is treated as a direct
> subtype of all the possible AttributeDescriptions that could be made
> up of all lesser combinations the options"
>
> That description is pretty ugly and could be fixed. It says that
> cn;a;b;c;d is in a direct subtype of: cn;a cn;a;b cn;a;c cn;a;d
> cn;a;b;c cn;a;b;d cn;a;c;d cn;b cn;b;c cn;b;d cn;b;c;d cn;c cn;c;d
> cn;d
>
> This also tells me that attribute subtype inheritance is at most two
> levels, but infinitely wide (leaf can multiply inherit from any number
> of supertypes)
>
> or
>
> "An AttributeDescription with one option is treated as a direct
> subtype of the attribute type without any options. An
> AttributeDescription with more than one option is treated as a direct
> subtype of all the possible AttributeDescriptions that could be made
> up of all combinations the options sans one option"
>
> Using the former example, this produces:
> cn;a (direct subtype of cn)
> cn;b (direct subtype of cn)
> cn;c (direct subtype of cn)
> cn;d (direct subtype of cn)
> cn;a;b (direct subtype of cn;a and cn;b)
> cn;a;c (direct subtype of cn;a and cn;c)
> cn;a;d (direct subtype of cn;a and cn;d)
> cn;b;c (direct subtype of cn;b and cn;c)
> cn;b;d (direct subtype of cn;b and cn;d)
> cn;c;d (direct subtype of cn;c and cn;d)
> cn;a;b;c (direct subtype of cn;a;b and cn;a;c and cn;b;c)
> cn;a;b;d (direct subtype of cn;a;b and cn;a;d and cn;b;d)
> cn;a;c;d (direct subtype of cn;a;c and cn;a;d and cn;c;d)
> cn;b;c;d (direct subtype of cn;b;c and cn;b;d and cn;c;d)
> cn;a;b;c;d (direct subtype of cn;a;b;c and cn;a;b;d and cn;a;c;d)
>
>
> In the context of language tags, the implications might be benign, but
> when combining disparate options some combinations might cause
> problems.
>
> I personally prefer 1). Though it may be less flexible, It's simpler
> to understand and fits well with the current subtyping model.
>
> Jim
>
>
> >>> "David Chadwick" <d.w.chadwick@salford.ac.uk> 9/23/00 5:11:55 AM
> >>> >>>
>
> > Yes, I'm reading "direct" into the 2251 statement. David has argued
> > that: cn;lang-en-US;lang-ja is a direct subtype of cn;lang-en-US,
> > which in turn is a direct subtype of cn. Does this also mean that
> > it's also a subtype of cn;lang-ja,
>
> Yes, I would say so. The new dual language subtype is a subtype
> of both single language subtypes. The order does not matter. We
> have
>
> supertype
> / \
> subtype 1 subtype 2
> \ /
> subtype1-2
>
> David
>
> >or is it strictly a right to left thing?
> > If r to l, then the attribute type option ordering restriction will
> > get in people's way.
> >
> > Jim
> >
>
>
> ***************************************************
>
> 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.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
>
> ***************************************************
>
***************************************************
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.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
***************************************************