@Override
    public Connection crearConexion() {
        try {
            InitialContext initialContext = new InitialContext();
            DataSource dataSource = (DataSource) initialContext.lookup("java:comp/env/jdbc/ausiasyield");
            Connection connection = dataSource.getConnection();
            return connection;
        } catch (NamingException ex) {
            throw new RuntimeException(ex);
        } catch (SQLException ex) {
            throw new RuntimeException(ex);
        }

    }