LDAP Package

The javax.naming.ldap package contains classes and interfaces for using features that are specific to the LDAP v3 that are not already covered by the more generic javax.naming.directory package. In fact, most JNDI applications that use the LDAP will find the javax.naming.directory package sufficient and will not need to use the javax.naming.ldap package at all. This package is primarily for those applications that need to use "extended" operations, controls, or unsolicited notifications.

"Extended" Operation
In addition to specifying well-defined operations such as search and modify, the LDAP v3 (RFC 2251) specifies a way to transmit yet-to-be defined operations between the LDAP client and the server. These operations are called "extended" operations. An "extended" operation may be defined by a standards organization such as the Internet Engineering Task Force (IETF) or by a vendor. This package defines classes for the Start TLS extension.
Controls
The LDAP v3 allows any request or response to be augmented by yet-to-be defined modifiers, called controls . A control sent with a request is a request control and a control sent with a response is a response control . A control may be defined by a standards organization such as the IETF or by a vendor. Request controls and response controls are not necessarily paired, that is, there need not be a response control for each request control sent, and vice versa.
Unsolicited Notifications
In addition to the normal request/response style of interaction between the client and server, the LDAP v3 also specifies unsolicited notifications--messages that are sent from the server to the client asynchronously and not in response to any client request.
The LDAP Context
The LdapContext interface represents a context for performing "extended" operations, sending request controls, and receiving response controls. Examples of how to use these features are described in the Controls and Extensions lesson.

JNDI Overview