Trigger to call an external program

I'm doing a low cost, low performance roll your own replication project,
between various offices around Australia.  The replication is
asynchronous, and peer to peer.  I've looked at the various replication
projects, and for one reason or another, they're too hard.

My design uses jabber as middleware, using python scripts to do the hard
work.  However, it depends on triggers calling my python scripts to
work.  I can't find a way to call an external script from a trigger.
I've searched the archives, and found a few other people asking the same
question, but no answers (apart from the odd sanctimonious "well you
shouldn't be doing that..." :-).

I thought I was onto a winner with pgplsh, but I can't get it to compile
with 7.3.4, although it compiled beautifully with 7.2.1.

Using python as a trigger language also seems to be a non-starter,
because the restricted python environment isn't yet working.

So...  Is there an easy way to call a script from a trigger?

Thanks

Alan Graham

--
Alan Graham <alan.graham@infonetsystems.com.au>