Module java.naming

Package javax.naming

Provides the classes and interfaces for accessing naming services.

This package defines the naming operations of the Java Naming and Directory Interface™ (JNDI).   JNDI provides naming and directory functionality to applications written in the Java programming language. It is designed to be independent of any specific naming or directory service implementation. Thus a variety of services--new, emerging, and already deployed ones--can be accessed in a common way.

Context

This package defines the notion of a context, represented by the Context interface. A context consists of a set of name-to-object bindings. Context is the core interface for looking up, binding, unbinding, and renaming objects, and for creating and destroying subcontexts.

lookup() is the most commonly used operation. You supply lookup() the name of the object you want to look up, and it returns the object bound to that name. For example, the following code fragment looks up a printer and sends a document to the printer object to be printed: 

Printer printer = (Printer)ctx.lookup("treekiller");
printer.print(report);

Names

Every naming method in the Context interface has two overloads: one that accepts a Name argument and one that accepts a string name. Name is an interface that represents a generic name--an ordered sequence of zero of more components. For these methods, Name can be used to represent a composite name (CompositeName) so that you can name an object using a name which spans multiple namespaces.

The overloads that accept Name are useful for applications that need to manipulate names: composing them, comparing components, and so on. The overloads that accept string names are likely to be more useful for simple applications, such as those that simply read in a name and look up the corresponding object.

Bindings

The Binding class represents a name-to-object binding. It is a tuple containing the name of the bound object, the name of the object's class, and the object itself.

The Binding class is actually a subclass of NameClassPair, which consists simply of the object's name and the object's class name. The NameClassPair is useful when you only want information about the object's class and do not want to pay the extra cost of getting the object.

References

Objects are stored in naming and directory services in different ways. If an object store supports storing Java objects, it might support storing an object in its serialized form. However, some naming and directory services do not support the storing of Java objects. Furthermore, for some objects in the directory, Java programs are but one group of applications that access them. In this case, a serialized Java object might not be the most appropriate representation. JNDI defines a reference, represented by the Reference class, which contains information on how to construct a copy of the object. JNDI will attempt to turn references looked up from the directory into the Java objects they represent, so that JNDI clients have the illusion that what is stored in the directory are Java objects.

The Initial Context

In JNDI, all naming and directory operations are performed relative to a context. There are no absolute roots. Therefore JNDI defines an initial context, InitialContext, which provides a starting point for naming and directory operations. Once you have an initial context, you can use it to look up other contexts and objects.

Exceptions

JNDI defines a class hierarchy for exceptions that can be thrown in the course of performing naming and directory operations. The root of this class hierarchy is NamingException. Programs interested in dealing with a particular exception can catch the corresponding subclass of the exception. Otherwise, programs should catch NamingException.

Package Specification

The JNDI API Specification and related documents can be found in the JNDI documentation.
Since:
1.3