I have to implement a very minimal blockchain (Ethereum) interface for OctoPrint on Raspberry which should make two very simple transactions: job_started and job_finished. These transactions could be triggered by two simple python functions. How I can edit the Octoprint server-side APIs functions?
(OctoPrint 0.15.10, OctoPi 0.16, Makerbot Replicator 2c (GPX plugin), 7.6)
What does "I have to" mean? Work or school assignment?
Should be pretty easy to listen for those events.
I have to develop a prototype for my thesis in university. Using APIs is ok, but for my specific case is better to implement transaction functions inner OctoPrint code, onto the Raspberry runs a light Ethereum node.
could we have at least 3d printing clean from that bc garbage ppl are trying to peddle everywhere 
there's no valid reason to implement that as part of octoprint code. if you really have to develop it make a plugin, it's clean and does the same thing..
For reference....this is what @tedder was talking about using assuming you're going to develop a plugin.
http://docs.octoprint.org/en/master/plugins/mixins.html#eventhandlerplugin
Otherwise you could use the config.yaml and add the external python calls to whatever...
http://docs.octoprint.org/en/master/events/index.html#sec-events