baseimage-tutorial-framework/lib/tfw/networking/serialization.py

# Copyright (C) 2018 Avatao.com Innovative Learning Kft.
# All Rights Reserved. See LICENSE file for details.
"""
TFW JSON message format

message:
{
    "key":     string,    # addressing
    "data":    {...},     # payload
    "trigger": string     # FSM trigger
}

ZeroMQ's sub-pub sockets use enveloped messages
(http://zguide.zeromq.org/page:all#Pub-Sub-Message-Envelopes)
and TFW also uses them internally. This means that on ZMQ sockets
we always send the messages key separatley and then the actual
message (which contains the key as well) like so:

socket.send_multipart([message['key'], message])

The purpose of this module is abstracting away this low level behaviour.
"""

import json


def serialize_tfw_msg(message):
    return serialize_all(message['key'], message)


def deserialize_tfw_msg(*args):
    return deserialize_all(*args)[1]


def serialize_all(*args):
    return tuple(_serialize_single(arg) for arg in args)


def deserialize_all(*args):
    return tuple(_deserialize_single(arg) for arg in args)


def _serialize_single(data):
    if not isinstance(data, str):
        data = json.dumps(data)
    return encode_if_needed(data)


def _deserialize_single(data):
    try:
        return json.loads(data)
    except ValueError:
        return decode_if_needed(data)


def encode_if_needed(value):
    if isinstance(value, str):
        value = value.encode('utf-8')
    return value


def decode_if_needed(value):
    if isinstance(value, (bytes, bytearray)):
        value = value.decode('utf-8')
    return value