ghost/core/server/web/parent/middleware/emit-events.js

const INVALIDATE_ALL = '/*';

// Emit the site.changed event, a special model event used for webhooks
const events = require('../../../lib/common/events');

module.exports = function emitEvents(req, res, next) {
    res.on('finish', function triggerEvents() {
        if (res.get('X-Cache-Invalidate') === INVALIDATE_ALL) {
            events.emit('site.changed');
        }

        res.removeListener('finish', triggerEvents);
    });
    next();
};