The Java EE 5 Tutorial

Creating a Reference to an Enterprise Bean Instance

Java EE application clients refer to enterprise bean instances by annotating static fields with the @EJB annotation. The annotated static field represents the enterprise bean’s business interface, which will resolve to the session bean instance when the application client container injects the resource references at runtime.

@EJB
private static Converter converter;

The field is static because the client class runs in a static context.