About Class Of Service - Netscape DIRECTORY SERVER 6.1 - DEPLOYMENT Deployment Manual

About Class of Service

A class of service (CoS) allows you to share attributes between entries in a way that
is invisible to applications. With CoS, some attribute values may not be stored with
the entry itself. Instead, they are generated by class of service logic as the entry is
sent to the client application.
For example, your directory contains thousands of entries that all share the
common attribute
facsimileTelephoneNumber
number, you would need to update each entry individually, a large job for
administrators that runs the risk of not updating all entries. With CoS, you can
generate the attribute dynamically. The
stored in one place, and each entry points to that place to give a value to their fax
number attribute. For the application, these attributes appear just like all other
attributes, despite that they are not actually stored on the entries themselves.
Each CoS is comprised of the following entries in your directory:
• CoS Definition Entry—The CoS definition entry identifies the type of CoS you
are using. It is stored as an LDAP subentry below the branch it affects.
• Template Entry—The template entry contains a list of the shared attribute
values. Changes to the template entry attribute values are automatically
applied to all the entries sharing the attribute.
The CoS definition entry and the template entry interact to provide attribute values
to their target entries, the entries within their scope. The value they provide
depends upon the following:
• The entry's DN (different portions of the directory tree might contain different
CoS).
• A service class attribute value stored with the entry.
The absence of a service class attribute can imply a specific default CoS.
• The attribute value stored in the CoS template entry.
Each CoS template entry supplies the attribute value for a particular CoS.
• The object class of the entry.
CoS attribute values are generated only when an entry contains an object class
allowing the attribute when schema checking is turned on, otherwise all
attribute values are generated.
• The attribute stored in some particular entry in the directory tree.
. Traditionally, to change the fax
facsimileTelephoneNumber
Chapter 4 Designing the Directory Tree
Grouping Directory Entries
attribute is
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