Directory and LDAP Packages
Trail: Java Naming and Directory Interface
Lesson: Overview of JNDI

Directory and LDAP Packages

Directory Package

The package extends the javax.naming package to provide functionality for accessing directory services in addition to naming services. This package allows applications to retrieve associated with objects stored in the directory and to search for objects using specified attributes.

The Directory Context

The DirContext interface represents a directory context. DirContext also behaves as a naming context by extending the Context interface. This means that any directory object can also provide a naming context. It defines methods for examining and updating attributes associated with a directory entry.

You use getAttributes() method to retrieve the attributes associated with a directory entry (for which you supply the name). Attributes are modified using modifyAttributes() method. You can add, replace, or remove attributes and/or attribute values using this operation.
DirContext contains methods for performing content based searching of the directory. In the simplest and most common form of usage, the application specifies a set of attributes possibly with specific values to match and submits this attribute set to the search() method. Other overloaded forms of search() support more sophisticated search filters.

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 package. In fact, most JNDI applications that use the LDAP will find the 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.
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 JNDI Tutorial's Controls and Extensions lesson.

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