Getting Stuff from the Container

Generally speaking the only way to get a Container-Managed Resource is via dependency injection or lookup from within a Container-Managed Component.

The unbreakable rules. Read these over and over again when things don't work.

java:comp/env is the spec defined namespace for lookup of any Container-Managed Resource
java:comp/env is empty by default
java:comp/env is read-only at runtime
java:comp/env is populated by Declaring References to Container-Managed Resource via xml or annotation
only Container-Managed Components, not their libraries, can Declare References via xml or annotation
only Container-Managed Components, not their libraries, can get dependency injection of Container-Managed Resources
only Container-Managed Components, and their libraries, may lookup from java:comp/env
you must use the no-arg 'new InitialContext()' constructor to lookup something from java:comp/env
the annotations and xml for Declaring References are identical in functionality, both always configure lookup with optional dependency injection

InitialContext Lookups

Server side beans should access other beans on the server via the default no args constructor (EJB 3 spec 15.3.1 Bean Provider's Responsibilities).
Container side lookup names must be preceded with java:comp/env, as in java:comp/env/myBean. e.g.
```
initialContext.lookup("java:comp/env/beanName")
```
note that java:comp/env/ is empty by default, and you need to declare your references, whether via xml or annotations
- Declared via annotations
```
@EJB(name="myBean", beanInterface = IMyBean.class)
public class DependentBean ....
```
- Declared via xml INCOMPLETE
Clients is a good reference for more complex lookups, including authentication (only for non-standard clients not running in an EJB container).

Some important things to realize about dependency injections.

@EJB IMyBean myBean is syntactic sugar for lookups (as follows), and is overridden by xml

initialContext = new InitialContext();
initialContext.lookup("java:comp/env/beanName")