app.get('/pdf/:id', function(req, res) {

GET http://localhost/pdf/123?option=456&clientId=789

req.query == { option: '456' }
req.params == { id: '123' }

curl 'http://localhost/pdf/123?option=456&clientId=789'

app.get('/pdf/:id', function(req, res) {
    console.log(req.params);
    console.log(req.query);

    res.end();
});

[ id: '123' ]
{ option: '456', clientId: '789' }
GET /pdf/123?option=456&clientId=789 200 1ms