Bridge Talk

When you want to chain several applications together Adobe has a little thing called "Bridge Talk"

var bt = new BridgeTalk();
bt.target = "aftereffects";
var script = "alert(app.version)";
bt.body = script;
bt.send();

That's cool. Sad thing is you need to provide the script as String to the BridgeTalk class. Best way is to develop two scripts and then read in one file as string. You will have to think about things like linefeeds, encoding, comments etc.

You can look it up in the Javascript Tools Guide. Open it from the help menu in the Extendscript Toolkit.