########
# Copyright (c) 2015 GigaSpaces Technologies Ltd. All rights reserved
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#        http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
#    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    * See the License for the specific language governing permissions and
#    * limitations under the License.

import abc


class Loader(object):

    __metaclass__ = abc.ABCMeta

    @abc.abstractmethod
    def load(self):

        """

        this method serves as the initial load function for the storage layer.
        its purpose is to load the storage with all the available hosts.
        hosts are represented as dictionaries with the following keys:

        {
            'public_address': public ip address or hostname (optional),
            'host': internal ip address or hostname,
            'port': port to communicate to,
            'auth': {
                'username': username to connect to the host with,
                'password': password to connect to the host with (optional),
                'keyfile': path to a key file that enables ssh
                           connection to the host (optional)
            }
        }

        :return: an iterable collection (or generator) of host dictionaries.
        """
