def create_filenames(msg_id, base_dir):
    """Return the response and request filenames and associated paths"""
    request_filename = msg_id + '.request'
    request_file_path = base_dir + '/' + request_filename
    response_filename = msg_id + '.response'
    response_file_path = base_dir + '/' + response_filename
    return [request_filename, request_file_path, response_filename, response_file_path]