Eventual consistency without magic: when 3 systems live their own lives
A classic distributed-systems story: you save a change, and then each external system processes it at its own pace. Using SellerHub and PDP Mobile as examples, here’s what helps keep things in sync.
We ran into this in two projects right away: SellerHub and PDP Mobile. Classic 2025 distributed systems: you hit “save”, and then each external system does its thing at its own pace 😅
In SellerHub, we change a price — and it has to be pushed to 3 marketplaces. But any one of them can say, “Nope, not accepting it.” In PDP Mobile, we create a pass in PDP, an external CRM, and СКУД at the same time — and each integration can fail independently.
What worked for us:
• retry logic — without it, these chains just fall apart
• idempotency — so a повторный request doesn’t create duplicates and chaos
• desync monitoring — otherwise you won’t learn about the bug from logs, but from a very “happy” user
The main takeaway: eventual consistency is not “it’ll line up by itself at some point”, but discipline, observability, and a lot of careful integration work. A kind of DevOps detox after “let’s just call the API.”