Designing The Directory Schema; Schema Design Process Overview; Standard Schema - Red Hat DIRECTORY SERVER 8.1 - DEPLOYMENT Deployment Manual

Chapter 3.

Designing the Directory Schema

Chapter 2, Planning the Directory Data
The site survey conducted in revealed information about
the data which will be stored in the directory. The directory schema describes the types of data in
the directory, so determining what schema to use reflects decisions on how to represent the data
stored in the directory. During the schema design process, each data element is mapped to an LDAP
attribute, and related elements are gathered into LDAP object classes. A well-designed schema helps
to maintain the integrity of the directory data.
This chapter describes the directory schema and how to design a schema for unique organizational
needs.
Section 6.4.4, "Schema Replication".
For information on replicating a schema, see

3.1. Schema Design Process Overview

During the schema design process, select and define the object classes and attributes used to
represent the entries stored by Red Hat Directory Server. Schema design involves the following steps:
1. Choosing predefined schema elements to meet as many of data needs as possible.
2. Extending the standard Directory Server schema to define new elements to meet other remaining
needs.
3. Planning for schema maintenance.
The simplest and most easily-maintained option is to use existing schema elements defined in
the standard schema provided with Directory Server. Choosing standard schema elements helps
ensure compatibility with directory-enabled applications. Because the schema is based on the LDAP
standard, it has been reviewed and agreed to by a wide number of directory users.

3.2. Standard Schema

The directory schema maintains the integrity of the data stored in the directory by imposing constraints
on the size, range, and format of data values. The schema reflects decisions about what types of
entries the directory contains (like people, devices, and organizations) and the attributes available to
each entry.
The predefined schema included with Directory Server contains both the standard LDAP schema
as well as additional application-specific schema to support the features of the server. While this
schema meets most directory needs, new object classes and attributes can be added to the schema
Section 3.4,
(extending the schema) to accommodate the unique needs of the directory. See
"Customizing the Schema"
for information on extending the schema.
3.2.1. Schema Format
Directory Server bases its schema format on version 3 of the LDAP protocol. This protocol requires
directory servers to publish their schema through LDAP itself, allowing directory client applications to
retrieve the schema programmatically and adapt their behavior accordingly. The global set of schema
for Directory Server can be found in the cn=schema entry.
19