advanced · reliability

Two Clients, One Resource

Two clients load the same resource, both edit it, and both save. Design the API so the second save doesn't silently destroy the first.

Practical scenario

Two support agents open the same customer record; one fixes the address, the other fixes the phone number, and whoever saves last erases the other's fix.

What it tests

  • • Recognition of the lost-update pattern
  • • Version/ETag mechanics with If-Match and 409/412
  • • Who resolves the conflict, and how