Messages

A message is a data container used to exchange data across nodes.

property	type	description
self.creator	str	name or id of the creating node
self.version	int	message data version
self.payload	BasicPayload	data to be transferred upstream in the pipeline
self.meta	dict	message metadata
self.timers	dict	collection of timers to evaluate performed data operations

An empty message is created with:

• creator set to None

• version set to -1

The message payload is an object of type BasePayload (or any of its derived types; see the payload doc page for more details). When a message is created, its payload type should be specified.

method	arguments	description
Message.from_message()	(Message, bool)	create a message by copying another message
self.to_dict()		convert the message to a dictionary
self.to_json()		convert the message to a json string
self.timer()	(str, float)	add timer to message

Notes:

• currently, to_json() simply returns the json.dumps() on the dictionary version of a message; this means that generating a json string for the message will fail if the message payload is not serialisable using the encoder function provided as argument

Timers

In order to keep track of any operations performed to generate the data contained in a message, a context manager, timeit, is offered to automatically create within the message timers dictionary a relevant entry.

>>> m = Message()
>>> with m.timeit('timer_name'):
>>>     time.sleep(1)
>>> m.timers
{'timer_name': 1.001392364501953}

Alternatively, set a timer using the timer() method:

>>> m = Message()
>>> m.timer('timer_name', 1.1)
>>> m.timers
{'timer_name': 1.1}