JNDI - Java Naming and Directory Interface

The Java Naming and Directory Interface (JNDI) is a standard extension to the Java platform, providing Java technology-enabled applications with a unified interface to multiple naming and directory services in the enterprise. As part of the Java Enterprise API set, JNDI enables seamless connectivity to heterogeneous enterprise naming and directory services. Developers can now build powerful and portable directory-enabled applications using this industry standard.

The JNDI API is used to access naming and directory services. As such, it provides a consistent model for accessing and manipulating such enterprise-wide resources as DNS, LDAP, local filesystems, or objects in an application server.
In JNDI, every node in a directory structure is called a context. Every JNDI name is relative to a context; there is no notion of an absolute name. An application can obtain its first context using the InitialContext class: Context ctx = new InitialContext(); From this initial context, the application can traverse the directory tree to locate the desired resources or objects. For example, assume that you have deployed an EJB within WebLogic Server and bound the home interface to the name myApp.myEJB. A client of this EJB, after obtaining an initial context, could then locate the home interface using: MyEJBHome home = ctx.lookup( "myApp.myEJB" ); Once you have a reference to the acquired object -- in this case, the home interface of the EJB -- it is then possible to invoke methods on it. We will discuss this further in the section below entitled "Enterprise Java Beans." The above discussion of JNDI is just the tip of the iceberg. In addition to looking up objects in a context, JNDI also provides methods to:

• Insert, or bind, an object into a context. This is effectively what you do when you deploy an EJB.
• Remove an object from a context.
• List all objects within a context.
• Create and delete subcontexts.