Need to understand Node, Computer, Queue for Rancher plugin

[Joe Fair]

I've inherited a Rancher Plugin that (almost) works for freestyle jobs.  

However, I'm trying to debug it, and I can't quite wrap my mind around the relationship between

  Computer

  Node

  AbstractJob

  AssignmenAction

  

Is there a document, webinar, or tutorial that I can use to see the relationships and some of the intent?

I've seen the standard plugin docs, which talk about implementing a build step.  This designates the freestyle job to run remotely.

Thanks,

Joe