[Zope-CMF] More DC workflow questions

[John Morton]

I'm working on an advanced link product, which, amongst other things, has a 
method for checking whether the URL is accessable, and keeps track of the 
number of errors encountered running the check method. The idea is that an 
automatic transition will move a given link to a state called 'broken' if a 
certain number of errors have occured.

After a bit of experimentation I discovered that automatic transitions aren't 
quite as automatic as I'd hoped, so I made another transition called 'check' 
which wraps the link checking method in a script and stays in state. Calling 
this action causes the automatic transtion to be called, it's guard checked 
and the transition to broken made where appropriate. 

But I'm still confused about when it all happens, and other things related to 
workflows:

 - When are the so called 'automatic' transitions triggered, and in what order
 are they processed?

 - What are 'WorkflowMethod' trigger?
 
 - When do scripts execute? What happens if they fail and raise an exception?

Thanks,
John