Determining Your Requirements

Understanding and Deploying LDAP Directory Services > 7. Schema Design > The Schema Checking Process

<  BACK

CONTINUE  >

153021169001182127177100019128036004029190136140232051053055078214173171147227047207228

The Schema Checking Process

When a new entry is added to the directory or an existing entry is modified, the directory server that processes the request goes through a schema checking process before committing the add or modify request. The schema checking process is done before the directory database itself is altered and ensures that all new or modified directory entries conform to the schema rules. If an entry violates any of the schema rules in effect, the request is rejected by the directory server and a Constraint Violation error is returned to the LDAP client.

The steps a server typically performs when checking schema are as follows :

1. Verify that all new or modified values conform to the syntax rules.

2. Verify that at least one value for the objectclass attribute is present.

3. For each object class, ensure that at least one value for each of the mandatory attributes is present.

4. Check each attribute to make sure it is allowed by one of the object classes and that the attribute only has one value if it is a single-valued attribute.

Note that the specifics and order of execution of some of the steps shown may vary in different directory service implementations . However, the basic idea is always the same: the resulting entry (whether new or modified) is checked for complete conformance with the server's schema rules, and an error is sent to the directory client if any problems are found. If there is a schema violation, the entire add or modify operation is rejected by the server.

Some implementations, such as the U-M slapd server and the Netscape Directory Server, provide a way to disable schema checking entirely, in which case entries that are added or modified are not checked against the schema rules at all.

Understanding and Deploying LDAP Directory Services,  2002 New Riders Publishing

<  BACK

CONTINUE  >

Index terms contained in this section

checking
          schemas 2nd 3rd
                    Constraint Violation errors
Constraint Violation error
          schema checking process
directories
         schemas
                    checking process 2nd 3rd 4th
schemas
          checking process 2nd 3rd
                    Constraint Violation errors

2002, O'Reilly & Associates, Inc.