def get(key, node=None, default=None):
    """
    Retrieve data
    :param key: 
    :param node: the node_key or the dot notation key to retrieve sub data
            get('myapp', 'this.is.a.nested.dict.data')
            get('my_other_data')
    :param default:
    :return: dict_dot dict object
    """
    d = AppData.get_by_key(key)
    if d:
        data = utils.dict_dot(d)
        return data.get(node, default) if node else data
    return {}