Sun Java System Application Server Platform Edition 9 Administration Guide

Chapter 5 JNDI Resources

The Java Naming and Directory Interface (JNDI) is an application programming interface (API) for accessing different kinds of naming and directory services. Java EE components locate objects by invoking the JNDI lookup method.

JNDI is the acronym for the Java Naming and Directory Interface API. By making calls to this API, applications locate resources and other program objects. A resource is a program object that provides connections to systems, such as database servers and messaging systems. (A JDBC resource is sometimes referred to as a data source.) Each resource object is identified by a unique, people-friendly name, called the JNDI name. A resource object and its JNDI name are bound together by the naming and directory service, which is included with the Application Server. To create a new resource, a new name-object binding is entered into the JNDI.

This chapter contains the following sections:

Java EE Naming Services

A JNDI name is a people-friendly name for an object. These names are bound to their objects by the naming and directory service that is provided by a Java EE server. Because Java EE components access this service through the JNDI API, the object usually uses its JNDI name. For example, the JNDI name of the Java DB database is jdbc/derby. When it starts up, the Application Server reads information from the configuration file and automatically adds JNDI database names to the name space.

Java EE application clients, enterprise beans, and web components are required to have access to a JNDI naming environment.

The application component's naming environment is a mechanism that allows customization of the application component's business logic during deployment or assembly. Use of the application component's environment allows the application component to be customized without the need to access or change the application component's source code.

A Java EE container implements the application component's environment, and provides it to the application component instance as a JNDI naming context. The application component's environment is used as follows:

Each application component defines its own set of environment entries. All instances of an application component within the same container share the same environment entries. Application component instances are not allowed to modify the environment at runtime.

Naming References and Binding Information

A resource reference is an element in a deployment descriptor that identifies the component’s coded name for the resource. More specifically, the coded name references a connection factory for the resource. In the example given in the following section, the resource reference name is jdbc/SavingsAccountDB.

The JNDI name of a resource and the name of the resource reference are not the same. This approach to naming requires that you map the two names before deployment, but it also de-couples components from resources. Because of this de-coupling, if at a later time the component needs to access a different resource, the name does not need to change. This flexibility also makes it easier for you to assemble Java EE applications from preexisting components.

The following table lists JNDI lookups and their associated references for the Java EE resources used by the Application Server.

Table 5–1 JNDI Lookups and Their Associated References

JNDI Lookup Name 

Associated Reference 


Application environment entries 


JDBC DataSource resource manager connection factories 


EJB References 


UserTransaction references 


JavaMail Session Connection Factories 


URL Connection Factories 


JMS Connection Factories and Destinations 


ORB instance shared across application components 

Using Custom Resources

A custom resource accesses a local JNDI repository and an external resource accesses an external JNDI repository. Both types of resources need user-specified factory class elements, JNDI name attributes, etc. Use the Admin Console to configure JNDI connection factory resources, J2EE resources, and access for these resources.

Using External JNDI Repositories and Resources

Often applications running on the Application Server require access to resources stored in an external JNDI repository. For example, generic Java objects could be stored in an LDAP server as per the Java schema. External JNDI resource elements let users configure such external resource repositories. The external JNDI factory must implement javax.naming.spi.InitialContextFactory interface.

An example of the use of an external JNDI resource is:

 <!-- external-jndi-resource element specifies how to access J2EE resources
 -- stored in an external JNDI repository. The following example
 -- illustrates how to access a java object stored in LDAP.
 -- factory-class element specifies the JNDI InitialContext factory that
 -- needs to be used to access the resource factory. property element
 -- corresponds to the environment applicable to the external JNDI context
 -- and jndi-lookup-name refers to the JNDI name to lookup to fetch the
 -- designated (in this case the java) object.
  <external-jndi-resource jndi-name="test/myBean"
    <property name="PROVIDER-URL" value="ldap://ldapserver:389/o=myObjects" />
    <property name="SECURITY_AUTHENTICATION" value="simple" />
    <property name="SECURITY_PRINCIPAL", value="cn=joeSmith, o=Engineering" />
    <property name="SECURITY_CREDENTIALS" value="changeit" />