Chapter 9. JNDI

The Java Naming and Directory Interface (JNDI) is an API that supports accessing naming and directory services in Java programs. The purpose of a naming service is to associate names with objects and to provide a way to access objects based on their names. You should be familiar with naming systems; you use them every day when you browse the filesystem on your computer or surf the Web by typing in a URL. Objects in a naming system can range from files in a filesystem and names located in Domain Name System (DNS) records to Enterprise JavaBeans (EJB) components in an application server and user profiles in an LDAP (Lightweight Directory Access Protocol) directory. If you want to use Java to write an application such as a search utility, a network-enabled desktop, an application launcher, an address book, a network management utility, or a class browserin short, anything that accesses objects in a naming systemJNDI is a good candidate for writing that application.

As its name implies, JNDI doesn't just deal with naming services . JNDI also encompasses directory services, which are a natural extension of naming services. The primary difference between the two is that a directory service allows the association of attributes with objects, such as an email address attribute for a user object, while a naming service does not. Thus, with a directory service, you can access the attributes of objects and search for objects based on their attributes. You can use JNDI to access directory services like LDAP and Novell Directory Services (NDS) directories.

JNDI is an integral part of the J2EE standard framework; it is used by J2EE components to access deployment information and various runtime resources, such as Enterprise JavaBean references, JDBC data sources, and so on. Details on how JNDI plays a role specifically in accessing EJBs can be found in Chapter 6. Full details on the use of JNDI for application deployment can be found in Chapter 2.