def get_schema():
    """Schema structure of this resource

    :return: schema dictionary
    :rtype: dict
    """
    return {'schema': {'schema_version': {'type': 'integer', 'default': 1},
        'host': {'schema_version': 1, 'title': 'Host', 'comment':
        'The host concerned by the acknowledge.', 'type': 'objectid',
        'data_relation': {'resource': 'host', 'embeddable': True},
        'required': True}, 'service': {'schema_version': 1, 'title':
        'Service', 'comment': 'The service concerned by the acknowledge.',
        'type': 'objectid', 'data_relation': {'resource': 'service',
        'embeddable': True}, 'required': True, 'nullable': True}, 'user': {
        'schema_version': 1, 'title': 'User', 'comment':
        'The user concerned by the acknowledge.', 'type': 'objectid',
        'data_relation': {'resource': 'user', 'embeddable': True},
        'required': True}, 'comment': {'schema_version': 1, 'title':
        'Comment', 'comment':
        'The comment of the acknowledge action. Free text.', 'type':
        'string', 'default': ''}, 'processed': {'schema_version': 1,
        'title': 'Processed', 'comment':
        'The action has been set on the host/service by Alignak and it can be considered as effective if processed is True'
        , 'type': 'boolean', 'default': False}, '_realm': {'schema_version':
        1, 'title': 'Realm', 'comment':
        'Realm this element belongs to. Note that this property will always be forced to the value of the concerned host realm.'
        , 'type': 'objectid', 'data_relation': {'resource': 'realm',
        'embeddable': True}}, '_sub_realm': {'schema_version': 1, 'title':
        'Sub-realms', 'comment':
        'Is this element visible in the sub-realms of its realm?', 'type':
        'boolean', 'default': True}, '_users_read': {'schema_version': 1,
        'type': 'list', 'schema': {'type': 'objectid', 'data_relation': {
        'resource': 'user', 'embeddable': True}}}}, 'schema_deleted': {}}
