When need the technician to go abroad, we
will arrange the technician. But the buyer should take all the cost, including Visa, Roundtrip ticket, suitable accommodation
and pay the service fee to the technician with $150/days.
Performance: we are not presenting any hard perf benchmarks here,
but a network Roundtrip(e.g. finding a session on database)
is likely to take more time than calculating an HMACSHA256 to validate a token and parsing its contents.