help: understanding objectclasses and schemas

[Martin Strohbach <uk73@rz.uni-karlsruhe.de>]

Hello everybody!

It seems to me that the concept of objectclasses and schemas is not clear to me,
so I would like to ask some questions:

As far as I understood schemas, they define what attributes an entry _must_ and
_is allowed_ to have. I am now in the situation that I want to deploy a ldap
server that is X.500 conform, for later (if at all) integration with X.500
directories. But I cannot understand why I should recognize the objectclass
"person" for example: if objectclasses only define what attributes a entry must
and is allowed to have, why isn't it then sufficient to have an objectclass
"myperson" that is identical with the X.500 objectclass "person" and allows or
requires other attributes? So it would be sufficient to add
"objectclass:myperson" instead of "objectclass:person" _and_
"objectclass:myperson".
So the next qusetion is obvious: is it possibleto subclass schemas. I think I
read about it, but I can't remember where.

Finally rfc2256 made me think of objectclass "top" and subschema. What is
objectclass subschema? rfc2256 says: servers MUST recognize this objectclass. By
the way: what does it mean "a server must recognize a objectclass". Does this
mean that each entry has to have such an attribute?
As I saw in many postings in this newsgroups people seem always to have an
attribute called "objectclass:top" as rfc2256 requires. But this objectclass
seems perfectcly strange to me: it requires nothing but objectclass and that is
always right, if the entry is of objectclass "top" (for I have to add the
attribute objectclass:top). So the next conclusion would be: why require the
attribute objectclass at all: either it is always included or it is not and then
no schema can require it, because the entry belongs to no objectclass.

I appreciate any help that brings light into the dark ...

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/_/  \   \ Martin Strohbach  ***  eMail uk73@rz.uni-karlsruhe.de \    /  \_\
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