Better routes

[Kotevode]

I don't really think that your routes are comfortable to use, for example:

GET /request_payment/:expect/:currency/:message/:seller/:customer/:callback_url

When you build a wrapper, joining these parameters is very tricky process: you should always match values with position. Maybe they should be passed via query string?

[Overtorment]

@Kotevode thanks for a suggestion! Perfectly valid point, but this is the default routing mechanism in Expressjs framework here.
If you can, please suggest an alternative.

[acalatrava]

AFAIK you can also use query string like this:

router.get('/request_payment', function(req, res) {
    var expect = req.query.expect;
    var currency = req.query.currency;
    var message = req.query.messge;
    ...
});

This should match a query like this:

GET /request_payment?currency=USD&message=This%20is%20your%20purchase&expect=100000