Featured White Papers

• Measuring Risk to Improve Java Software Quality
• Do You Really Get Classloaders?
• Pragmatic Continuous Delivery with Jenkins, Nexus, and LiveRebel
• Your Next Java Web App: Less XML, No Long Restarts, Fewer Hassles
• Coding with JRebel, Java Forever Changed
• 2012 Developer Productivity Report: Java Tools, Tech, Devs, and Data

Sponsored Links

• Graph databases are 1000x faster than relational.

  Learn More!

• Career opportunities at Harman- Careers That'll Rock Your Socks Off.

  Learn More!

• Developer-friendly Java PDF libraries by Qoppa Software

  Live Demos

• Stop blaming your app! Diagnose Java performance issues.

  Free tool >

• UrbanCode: Go From Continuous Integration to
  Continuous Delivery

  Learn More!

Sponsored Links

Optimize with a SATA RAID Storage Solution
Range of capacities as low as $1250 per TB. Ideal if you currently rely on servers/disks/JBODs

JNDI overview, Part 1: An introduction to naming services

Use JNDI to better manage your distributed applications

By Todd Sundsted, JavaWorld.com, 01/01/00

Page 3 of 4

JNDI solves this problem with the Name class and its subclasses and helper classes. The Name class represents a name composed of an ordered sequences of subnames, and provides methods for working with names independent of the underlying naming service.

A look at JNDI naming

As I mentioned above, it's important to remember that JNDI is an interface rather than an implementation. This fact has some disadvantages -- you need access to an existing naming service (such as an LDAP service) and you need to understand something about how it works in order to play with JNDI. On the other hand, it does allow JNDI to integrate seamlessly into an existing computing environment where an established naming service holds sway.

JNDI naming revolves around a small set of classes and a handful of operations. Let's take a look at them.

Context and InitialContext

The Context interface plays a central role in JNDI. A context represents a set of bindings within a naming service that all share the same naming convention. A Context object provides the methods for binding names to objects and unbinding names from objects, for renaming objects, and for listing the bindings.

Some naming services also provide subcontext functionality. Much like a directory in a filesystem, a subcontext is a context within a context. This hierarchical structure permits better organization of information. For naming services that support subcontexts, the Context class also provides methods for creating and destroying subcontexts.

JNDI performs all naming operations relative to a context. To assist in finding a place to start, the JNDI specification defines an InitialContext class. This class is instantiated with properties that define the type of naming service in use and, for naming services that provide security, the ID and password to use when connecting.

For those of you familiar with the RMI Naming class, many of the methods provided by the Context interface outlined below will look familiar. Let's take a look at Context's methods:

• void bind(String stringName, Object object): Binds a name to an object. The name must not be bound to another object. All intermediate contexts must already exist.
  
  
• void rebind(String stringName, Object object): Binds a name to an object. All intermediate contexts must already exist.
  
  
• Object lookup(String stringName): Returns the specified object.
  
  
• void unbind(String stringName): Unbinds the specified object.
  
  

The Context interface also provides methods for renaming and listing bindings.

• void rename(String stringOldName, String stringNewName): Changes the name to which an object is bound.
• NamingEnumeration listBindings(String stringName): Returns an enumeration containing the names bound to the specified context, along with the objects and the class names of the objects bound to them.
  
  
• NamingEnumeration list(String stringName): Returns an enumeration containing the names bound to the specified context, along with the class names of the objects bound to them.

Each of these methods has a sibling that takes a Name object instead of a String object. A Name object represents a generic name. The Name class allows a program to manipulate names without having to know as much about the specific naming service in use.