Setup
- Retail POS for Mac or PC
- Shopify Integration
Answer
Shopify rate limit calls (requests) to ease the load on their servers.
Whenever you make a call (when you log in, ask a question on your computer, or an app, click a button or save a change, you're making an call) this creates a load on the Shopify servers.
Shopify control this load with a leaky bucket algorithm. This allows the user to make variable amounts of calls and continue to make unlimited calls over time without overloading the servers.
The bucket size (limit) is 40 calls, with a leak rate of 2 calls per second that continually empties the bucket. The calls will be processed almost instantly if there is room in the bucket.
However, if it does hit the 40 call limit, the remaining updates will be queued and may not update to Shopify until there is room in the bucket once again. You can read more about it here.
Additional Information
The rate limit on Shopify is not based on the Retail POS integration, rather at the Shopify account-wide level. This includes the calls coming from all other installed apps/plugins to Shopify.