TCP/IP Tutorial and Technical Overview - IBM Redbooks

classes that a directory server can store and the attributes they contain are
described by a schema. A schema defines where object classes are allowed in
the directory, which attributes they must contain, which attributes are optional,
and the syntax of each attribute. For example, a schema might define a person
object class that requires that a person has a character-string surname attribute,
can optionally have a number-string telephoneNumber attribute, and so on.
Schema-checking ensures that all required attributes for an entry are present
before an entry is stored. Schemas also define the inheritance and subclassing
of objects, and where in the DIT structure (hierarchy) objects can appear.
Though an implementation can define any schema to meet its needs, RFC 4519
defines a few standard schemas. Table 12-7 lists a few of the common schema
(object classes and their required attributes). In many cases, an entry can consist
of more than one object class.
Table 12-7 Examples of object classes and required attributes
Object class Description Attributes
country Defines a country Required:
countryCode
Optional:
searchGuide
description
locality Defines a place in the physical
world
Because servers can define their own schema, LDAP includes the functionality
of allowing a client to query a server for the contents of the supported schema.
466 TCP/IP Tutorial and Technical Overview
Required:
None
Optional:
street
seeAlso
searchGuide
description
person Defines a person Required:
surname
commonName
Optional:
userPassword
telephoneNumber
seeAlso
description