Where to save stuff (in snap-agnostic way)

[Luca Dionisi]

What is the best place to write (and read) a temporary FIFO file from
a confined snap application?
This is for simple IPC between 2 processes of the same snap.
Before attempting to snap the application I was using a fixed filename
in /tmp. Admittedly poor solution.
The solution should be usable also with another packaging system.

--Luca

P.S. the problem with Vala library has been solved and I was able to
make the snap work in devmode. Now I am trying to move from devmode to
strict.