Re: [389-users] Question regarding Combining ObjectClasses to add attributes

Thanks for the quick response.



The RHN knowledgebase article I found was titled:  "How to use "host"
attribute to limit ldap users can be accessed by specified host?"  kb# 65838

https://access.redhat.com/knowledge/solutions/65838



From: Rich Megginson [mailto:[e-mail]]
Sent: Monday, July 09, 2012 9:14 AM
To: General discussion list for the 389 Directory server project.
Cc: Anderson, Cary@CIO
Subject: Re: [389-users] Question regarding Combining ObjectClasses to add attributes

On 07/09/2012 09:44 AM, Anderson, Cary@CIO wrote:

I have recently started working with the Director Server, and I have read the documents
for both 389 and RHDS, but I am having some difficulties regarding ObjectClass types, and
combining them in order to extend the available attributes for an object.  The documents
indicate that you can only have one Structural ObjectClass and multiple Aux.
ObjectClasses, and I'm a bit hazy on the rules for Abstract ObjectClasses.

If I take the example of needing to add the "host" attribute to a user object. 
A RHN knowledgebase article indicates to add the "hostobject" ObjectClass rather
than the "Account" ObjectClass.

Can you provide a link to this kbase article?



My assumption was that "hostobject" was an Aux. ObjectClass, and that
"Account" was Structural, but when I look at the two ObjectClasses via the
administrative GUI, they both have "Top" listed as the parent ObjectClass.  So
I'm not certain why one is appropriate and the other is not.
It would appear the console does not tell you if the objectclass is structural, auxiliary,
or abstract.  You cannot tell by just the inheritance - by default, all objectclasses have
"top" as the superior unless otherwise specified.

This is the official LDAPv3 description - http://www.ietf.org/rfc/rfc4512.txt

An entry may have only one STRUCTURAL objectclass, and multiple AUXILIARY objectclasses. 
Chances are you will want to use AUXILIARY objectclasses for your extra attributes (like
posixAccount) and just use one of the pre-defined objectclasses (like inetOrgPerson) as
your STRUCTURAL objectclass.



Moving forward I want to be able to combine ObjectClasses to extend available objects
without introducing data integrity issues in my ldap directory.  I am looking for some
clarification of rules regarding structural objectclasses,
See rfc4512


and if there is an easy way via the admin gui to tell the difference between structural,
auxillary, and abstract objectclasses.
No.  You'll have to search cn=schema to check:
ldapsearch -xLLL -s base -b "cn=schema" "objectclass=*" objectclasses
| perl -p0e 's/\n //g' | grep AUXILIARY

Note that ldapsearch wraps the output, so you'll have to use perl (or sed) to unwrap -
see http://richmegginson.livejournal.com/18726.html


Also will the directory do some sort of intregrity checking if you attempt to combine
improper objectclasses either via commandline or the admin gui?
Yes, although by default 389 will allow an entry to have multiple structural
objectclasses, but that will change in a future release, so don't rely on that
behavior.




Thanks


           Cary Anderson
              916.464.5108
Linux Support | Engineering Dept.





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