Sharing a transaction between programs.

I'd like to have two programs cooperating, each implementing a different module
of an application. I'd also wish they perform a single transaction (I'd use
distributed transaction if they were available). As this two application would
probably be written in different programming languages, I'd like to do something
like.

App1:
connect to the db;
begin transaction;
do work;
call app2 (app1 passes a 'handler' to the transaction to app2)
commit;

App2:
receive 'connection handler';
do work;

Is this (or something similar) possible?

Thanks!

Fernando.