Differences between LDAP 2 and LDAP 3

LDAP 3 defines a number of improvements that allow a more efficient implementation of the Internet directory user agent (DUA) access model. These changes include:

• Use of UTF-8 for all text string attributes to support extended character sets.
• Operational attributes that the directory maintains for its own use for example, to log the date and time when another attribute has been modified.
• Referrals allow a server to direct a client to another server that may have the information the client requested.
• Schema publishing with the directory, allowing a client to discover the object classes and attributes that a server supports.
• Extended searching operations to allow paging and sorting of results, and client-defined searching and sorting controls.
• Stronger security through an SASL-based authentication mechanism.
• Extended operations, providing additional functionality without changing the protocol version.

LDAP 3 is compatible with LDAP 2. An LDAP 2 client will be able to connect to an LDAP 3 server (this is a requirement of an LDAP 3 server). However, an LDAP 3 server can choose not to talk to an LDAP 2 client if LDAP 3 functionality is critical to its application.