class
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... Object Classes ...
... way of knowing what type of object a given entry represents. X.500
uses the concept of an "object class" to specify that information,
and an attribute named "objectClass" which each entry contains to
specify to which object class ...
... object class" to specify that information,
and an attribute named "objectClass" which each entry contains to
specify to which object class(es) the entry belongs.
...
... mandatory attributes, which must be present, and a set of optional
attributes, which may be present, in an entry of that class. An given
object class A may be a subclass of another class ...
... attributes, which may be present, in an entry of that class. An given
object class A may be a subclass of another class B, in which case
object class ...
... class. An given
object class A may be a subclass of another class B, in which case
object class A inherits all the mandatory and optional attributes of
...
... object class A may be a subclass of another class B, in which case
object class A inherits all the mandatory and optional attributes of
B in addition to its own.
...
... object classes in X.500 are arranged in a hierarchical manner
according to class inheritance; the following diagram shows a part of
the object class hierarchy.
...
... according to class inheritance; the following diagram shows a part of
the object class hierarchy.
...
... |_____________| and nooptional attributes.
| | |
| | | every other object class is a
________________| | | subclass of "top"...
| | ...
...
... "country" would inherit all of the "organization" inherited
mandatory and optional attributes from "top".
of the "country" class, including
the attribute which "country"
inherited from "top".
...
...
One major benefit of the object class concept is that it is in many
cases very easy to create a new object class ...
... object class concept is that it is in many
cases very easy to create a new object class which is only a slight
modification or extension of a previous class. For example, if I have
...
... create a new object class which is only a slight
modification or extension of a previous class. For example, if I have
already defined an object class for "person" which contains a
...
... modification or extension of a previous class. For example, if I have
already defined an object class for "person" which contains a
person's name, phone number, address ...
... fax number, I can easily
define an "Internet person" object class by defining "Internet
person" as a subclass of "person", with the additional optional
...
... e-mail address". Thus in my definition of the "Internet
Person" object class, all my "person" type attributes are inherited
from "person". There are other benefits which are beyond the scope of
this paper.
...
... Advanced searching capabilities.
The Directory supports arbitrarily complex searches at an
attribute level. As the object classes a specific entry
belongs to is maintained in the objectClass attribute, this
also allows Directory searches for specific types of objects.
...
... namespace, but local
specialized directories can also be implemented. Locally
defined extensions can include new object classes, new
attributes, and new attribute types.
...