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Chapter 2. EJB reference resolution

Introduction :

This section covers how JBoss implements @EJB and @Resource. Please note that XML always overrides annotations.

EJB references :

Rules for the @EJB annotation

  • 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:
    ProcessPayment myEjbref;
    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 <ejb-link>. 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

For XML the same rules apply as annotations