If I need to post a data from a controller to my main server.js, I usually do it like this:
$http.post('/auth/signup', user);
This goes from a controller
app.post('/auth/signup', function(req, res, next)
and this is function with req parameter's I'll catch. The question is how to do it backwards? Does express's instance provide a method to make a request by url? Does $http or something provide a method to catch a data?