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Saturday, July 14, 2012

JEE: Java Naming and Directory Interface API (JNDI)

The Java Naming and Directory Interface (JNDI) API provides naming and directory functionality, enabling applications to access multiple naming and directory services, including existing naming and directory services, such as LDAP, NDS,DNS, and NIS.

The JNDI API provides applications with methods for performing standard directory operations, such as associating attributes with objects and searching for objects using their attributes.

Using JNDI, a Java EE application can store and retrieve any type of named Java object, allowing Java EE applications to coexist with many legacy applications and systems.

Java EE naming services provide application clients, enterprise beans, and web components with access to a JNDI naming environment. A naming environment allows a component to be customized without the need to access or change the component’s source code. A container implements the component’s environment and provides it to the component as a JNDI naming context.

A Java EE component can locate its environment naming context by using JNDI interfaces. A component can create a javax.naming.InitialContext object and look up the environment naming context in InitialContext under the name java:comp/env.

A component’s naming environment is stored directly in the environment naming context or in any of its direct or indirect subcontexts.

A Java EE component can access named system-provided and user-defined objects. The names of system-provided objects, such as JTA UserTransaction objects, are stored in the environment naming context java:comp/env. The Java EE platform allows a component to name user-defined objects, such as enterprise beans, environment entries, JDBC DataSource objects, and message connections. An object should be named within a subcontext of the naming environment according to the type of the object.

For example, enterprise beans are named within the subcontext java:comp/env/ejb, and JDBC DataSource references are named within the subcontext java:comp/env/jdbc.