cek status
Notes :
- unique identifier for each request = ts + user_id
- if a request sends a previously used ts+user-id, this request is ignored.
- a user-id is only allowed to send 1 request for the same ts (per second)
so by using a user-id, the maximum number of trx/day is 86400.
- when the number of transactions per day is so high,
a buyer/member can use the 2nd user-id, or the 3rd, and so on.