code: public static String jndiLookup(String key) {
          String value = null;
          try {
              Context c = new InitialContext();
              value = (String) c.lookup(JNDI_PREFIX + key);
          } catch (NoInitialContextException e) {
              logger.trace("JNDI not configured for Sentry (NoInitialContextEx)");
          } catch (NamingException e) {
              logger.trace("No /sentry/" + key + " in JNDI");
          } catch (RuntimeException e) {
              logger.warn("Odd RuntimeException while testing for JNDI", e);
          }
          return value;
      }
docs: Looks up for a JNDI definition of the provided key.
  
  @param key name of configuration key, e.g. "dsn"
  @return the value as defined in JNDI or null if it isn't defined.