Session EJB and Servlet Collocated in Same WAR, JNDI Lookup

Internal

• EJB Concepts - Invoking into EJBs

Overview

This example describes the look up of an EJB and subsequent invocation, when the EJB and the calling component (a servlet, in this case) are part of the same WAR deployment artifact. The lookup is done via JNDI.

GitHub Example

https://github.com/NovaOrdis/playground/tree/master/jee/ejb/stateless-and-servlet-same-war-jndi

Business Interface Type Access

The EJB code and the calling component code are part of the same deployment unit, so the calling component has implicit access to the business interface class. No special configuration is needed here.

EJB Lookup

The EJB reference is looked up in JNDI using the portable JNDI EJB naming scheme.

In this case, the EJB is named SimpleStatelessBean, it is deployed as part of the wrapper-servlet.war, and implements only a single business interface, so the simplest possible JNDI name is "java:module/SimpleStatelessBean". "java:app/wrapper-servlet/SimpleStatelessBean" or "java:global/wrapper-servlet/SimpleStatelessBean" would also work.

For more details on the JNDI EJB naming scheme, see:

EJB Concepts - EJB and JNDI

The code that does the JNDI lookup is similar to:

SimpleStateless bean = null;

...

try {

   InitialContext  ic = new InitialContext();
   SimpleStateless bean = (SimpleStateless)ic.lookup("java:global/wrapper-servlet/SimpleStatelessBean");
}
catch(Exception e) {
    ...
}

EJB Invocation

Once the EJB reference is obtained from JNDI, business interface methods can be called on its reference:

...
bean.methodOne("something from servlet");