Node¶

Node is callable thing .In python world ,we have three callable things ,

function
function object. class with override `__call__`
lambada

Major work of user of databot shouble be writing core logic function, for parsing, mapping,calculating , aggregating. It is the main purpose of databot desing.

Pass into Node:¶

Node must have only one parameter. the pass in value is from upflow node return value.

Return from Node:¶

Node can return anything . list ,generator,raw value,tuple .

Attention

list will be unpacked into separate item . tuple will not be unpacked.
generator will be iterated by bot. so you can return a infinite generator to simulate a stream flow it is interested to test.
raw will put into queue.

How to handle Excpetion:¶

Exception behavior will act according to `config.Exception_policy = config.Exception_raise ` setting.

Exception_default:
	default exception policy is raise
Exception_raise:
	raise exception
Exception_ignore:
	ignore exception. exception raised from node will be suppressed.
Exception_retry:
	the value will put in input-queue after some delay.
Exception_pipein:
	the exception tread as returen value ,put in output queue. it will be usefull in blockedjoin route scenarios.