code: public final boolean lockItemIfAvailable(long lockID) throws SevereMessageStoreException
      {
          boolean locked = false;
          Membership membership = _getMembership();
          if (null != membership)
          {
              locked = membership.lockItemIfAvailable(lockID);
          }
          return locked;
      }
docs: Attempt to lock the item using the given lock ID. If the lock is
  succesful then the item behaves as if it were succesfully locked
  by a {@link LockingCursor} with the same lock ID. The lock is not
  persistent.
  NOTE: if the item is not in store then this method should return false
  rather than throwing an exception. The MP guys are expecting that the
  item should sometime be not-stored.
  
  @param lockID
  @return boolean true if successful
  @throws SevereMessageStoreException
  @throws MessageStoreException