[Question/Suggestion] Pass data of an output channel to the next one

[alexej-d]

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	no

I was wondering if it is possible to pass some of an output channel's returned data to the next channel in the same workflow?

Imagine you have a custom output channel that creates a PDF and you want to pass the URL of the PDF to the Email channel.

How would you do that? Maybe via a global service that stores the current lifecycle's context variables?