[agopaul]

This. Too bad many APIs around are designed without keeping in mind that timeouts and double submissions can occur.

A few years ago I had to integrate with another software vendor (using SOAP, sigh), and development went all smooth, testing too but when the integration went live we noticed that the VPN connection was somehow not working properly and we were getting 20% packet loss. Luckily, for each API call that would write data we would issue a unique "requestId" and implemented retry logic so double submissions (eg. due to timeouts) were discarded.

Needless to say, that saved our day and the project went smoothly even though it took a week to the DevOps guy to debug and fix the faulty VPN tunnel.