Connectivity is a Feature, Not a Given
Every POS deployment we have done in Pakistan ÔÇö from Karachi restaurants to Lahore retail chains ÔÇö has experienced connectivity issues. Power cuts, ISP outages, mobile data exhaustion. The question is not if your POS will go offline, but when.
Local-First with SQLite
Our POS stores every transaction in a local SQLite database first. The network sync happens asynchronously. From the cashier perspective, the system is always fast because it never waits on a network call.
Event-Sourced Sync
We use an event-sourced model: every state change is an append-only event. When connectivity returns, events replay in order against the server. Conflicts are rare because POS terminals rarely share inventory ÔÇö but when they occur, last-write-wins with a timestamp tiebreaker handles 99% of cases.
The 72-Hour Test
We simulate a 72-hour offline period during QA. The system must process transactions, print receipts, and sync correctly when reconnected. This test has caught three bugs in our sync logic that would have caused data loss in production.
Receipts Without Internet
Receipt printing is entirely local. We use ESC/POS commands directly to the thermal printer over USB or local network. Cloud receipt delivery is a bonus, not a dependency.