Java – JBoss 5 AS and EJB3 bean injection from servlets

ejb-3.0java-ee-5jboss

It was my understanding that JBossAS 5.x supported EJB3 bean injection in servlets with the @EJB3 annotation. I'm using the default configuration for JBossAS 5.0.1.GA and it's not working. I've added the mappedName argument to the @EJB annotation with the session beans JNDI name, and it just doesn't do anything. No apparent errors, the bean is just never injected.

The session beans are in the ejb-jar, the servlets in a war, everything is packaged in an ear. Manual JNDI lookups work just fine. Any ideas?

Best Answer

This may happen if your web.xml points to an older version of the spec. Ideally, it should be something like

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
         xmlns="http://java.sun.com/xml/ns/j2ee" 
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"   
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-app_2_5.xsd">

This link may help a little too.

Related Solutions

Can remote stateless session bean references be cached in EJB3

Yes, they can be cached. But I don't know if the behavior is defined what will happen should you have a cached reference and the server is rebooted underneath it. You can test that scenario, but the behavior may vary with the container.

Accessing an EJB3 bean in a jar from an independently deployed war (not packaged in ear)

I wish i understood this area of the EE spec well enough to give you a definitive answer, but i don't.

The JBoss EJB documentation has this to say:

The @EJB annotation also has a mappedName() attribute. The specification leaves this a vendor specific metadata, but JBoss recognizes mappedName() as the global JNDI name of the EJB you are referencing. If you have specified a mappedName(), then all other attributes are ignored and this global JNDI name is used for binding.

If you specify @EJB with no attributes defined [...] Then the following rules apply:

The EJB jar of the referencing bean is searched for an EJB with the interface, used in for @EJB injection. If there are more than one EJB that publishes same business interface, then an exception is thrown. If there is only one bean with that interface then that one is used.

Search the EAR for EJBs that publish that interface. If there are duplicates, then an exception is thrown. Otherwise the matching bean is returned.

Search globally in JBoss for an EJB of that interface. Again, if duplicates, an exception is thrown.

@EJB.beanName() corresponds to . If the beanName() is defined, then use the same algorithm as @EJB with no attributes defined except use the beanName() as a key in the search. An exception to this rule is if you use the ejb-link '#' syntax. The '#' syntax allows you to put a relative path to a jar in the EAR where the EJB you are referencing lives. See spec for more details

The "Search globally in JBoss for an EJB of that interface" certainly suggests that an injection like the one you wrote should work. Indeed, that it should work without the beanName. However, my suspicion is that from the point of view of a component in the WAR, a component in the EJB-JAR is remote, and therefore you will need to use the remote interface.

So, the first thing i'd try is:

@EJB
private IUserFacadeRemote userFacade;

Without a beanName, in case that's making trouble. It sounds like you've tried that, though.

If the normal approach to injection doesn't work, i might fall back to trying an injection via a mappedName, which in JBoss is a global JNDI name. So:

@EJB(mappedName = "java:global/Users-ejb/userFacade!facades.IUserFacadeRemote")
private IUserFacadeRemote userFacade;

This is obviously rather ugly.

Anyway, good luck!

EDIT: Something else you could try is to use a qualified relative beanName which explicitly names the EJB-JAR:

@EJB(beanName = "Users-ejb.jar#userFacade")
private IUserFacadeRemote userFacade;

Because the WAR and EJB-JAR are not packaged in an EAR, this might need to be:

@EJB(beanName = "../Users-ejb.jar#userFacade")
private IUserFacadeRemote userFacade;

But by this point i'm just guessing.

EDIT STRIKES BACK: We may have overlooked something very simple. The lookup attribute of the @EJB annotation lets you specify "A portable lookup string containing the JNDI name for the target EJB component", hence:

@EJB(lookup = "java:global/Users-ejb/userFacade!facades.IUserFacadeRemote")
private IUserFacadeRemote userFacade;

Might work. This is essentially a portable version of the JBoss-specific use of mappedName.

Best Answer

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Can remote stateless session bean references be cached in EJB3

Accessing an EJB3 bean in a jar from an independently deployed war (not packaged in ear)

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