result-final.js

// tracker middleware
app.use((req, res, next) => {
    if (req.metadata.event) {
        tracking(req.metadata.event);
        next();
    }
});

// logger middleware
app.use('/data', (req, res, next) => {
    if (req.metadata.info) {
        logger(req.metadata.info);
        next();
    }
});

// responder middleware
app.use((req, res, next) => {
    if (req.result) {
        res.json(req.result);
    } else {
        next(new Error('Result not found'));
    }
});