Drivers that drive me mad...

[Bruce Fitzsimons]

Hi peoples,

I just thought I'd throw this to the list and see if someone can tell me
WHY?

My dialogic driver has been sending me nutty for several days because
whenever I sent it a command, it would die. No visible exit signals or
anything. No reason that I could fathom, it worked fine from the shell.

The situation I had was :

1. voice_call process that calls...
2. erlogic.erl that is a server for the dialogic commands. Dialogic events
are received by a loop spawned from this driver and distributed(which seems
nasty but I don't see a way around it). the loop process opens the port
to...
3. erlogic_driver.so - the driver code

Everything worked fine until I sent a command to erlogic.erl and it
translated it and sent a command to the driver port (like a pid...but
different) port ! {self(), {command, {"xxx"}}}. At this point the driver
crashed and took the loop with it. I couldn't trap any message from it.

After a few days of mucking around with this, I decided that maybe the
process that opens a port should send the commands to it. And it
works....yay!

So my questions are - why are drivers ports different to pids? Is this
documented anywhere? and why does it die without a sound (not typical erlang
at all!). It seems to be the erlang interface code that kills it.

Cheers,
Bruce