idempotent services

[ahdinosaur]

trivial example: we use our client ids to ensure an operation only happens once

references:

• http://www.servicedesignpatterns.com/WebServiceInfrastructures/IdempotentRetry
• https://softwareengineering.stackexchange.com/questions/320143/should-an-idempotent-service-always-return-the-same
• https://medium.com/@foundev/event-sourcing-and-system-of-record-b919714512b8

[danalexilewis]

:)