105 lines
2.2 KiB
Python
105 lines
2.2 KiB
Python
"""
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TFW JSON message format
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message:
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{
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"key": string, # addressing
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"data": {...}, # payload
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"trigger": string # FSM trigger
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}
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ZeroMQ's sub-pub sockets use enveloped messages
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(http://zguide.zeromq.org/page:all#Pub-Sub-Message-Envelopes)
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and TFW also uses them internally. This means that on ZMQ sockets
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we always send the messages key separately and then the actual
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message (which contains the key as well) like so:
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socket.send_multipart([message['key'], message])
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The purpose of this module is abstracting away this low level behaviour.
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"""
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import json
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from functools import wraps
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def serialize_tfw_msg(message):
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"""
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Create TFW multipart data from message dict
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"""
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return _serialize_all(message['key'], message)
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def with_deserialize_tfw_msg(fun):
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@wraps(fun)
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def wrapper(message_parts):
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message = deserialize_tfw_msg(*message_parts)
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return fun(message)
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return wrapper
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def deserialize_tfw_msg(*args):
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"""
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Return message from TFW multipart data
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"""
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return _deserialize_all(*args)[1]
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def _serialize_all(*args):
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return tuple(
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_serialize_single(arg)
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for arg in args
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)
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def _deserialize_all(*args):
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return tuple(
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_deserialize_single(arg)
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for arg in args
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)
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def _serialize_single(data):
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"""
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Return input as bytes
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(serialize input if it is JSON)
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"""
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if not isinstance(data, str):
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data = message_bytes(data)
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return _encode_if_needed(data)
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def message_bytes(message):
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return json.dumps(message, sort_keys=True).encode()
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def _deserialize_single(data):
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"""
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Try parsing input as JSON, return it as
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string if parsing fails.
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"""
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try:
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return json.loads(data)
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except ValueError:
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return _decode_if_needed(data)
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def _encode_if_needed(value):
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"""
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Return input as bytes
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(encode if input is string)
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"""
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if isinstance(value, str):
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value = value.encode('utf-8')
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return value
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def _decode_if_needed(value):
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"""
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Return input as string
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(decode if input is bytes)
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"""
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if isinstance(value, (bytes, bytearray)):
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value = value.decode('utf-8')
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return value
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