Members book instantly, even when the finance system stalls

The client runs a member portal, a mobile app and a staff CRM for its gyms. An ERP holds the financial record and cannot be bypassed. Under load, one pricing call slowed past ten seconds, and some calls timed out.

Members expect a booking to go through at once. The finance system has to agree with every booking, and it is slow and sometimes unavailable.

1. Built a Laravel middleware between the portal, the app, the gym databases and the ERP, so the ERP’s formats are translated once, in one place, and never leak into the product.
2. Added a circuit breaker: after repeated failures, the middleware stops calling the ERP for a short time instead of stacking up timeouts.
3. Served cached data while it refreshes in the background, so members get fast answers that are only moments old.
4. Made bookings optimistic. A booking saves at once, a queued job confirms it with the ERP and retries on failure, and if the ERP refuses, the booking undoes itself and the member is told.
5. Added live seat counts, booking limits and automatic promotion from the waiting list.
6. Made the portal lighter by cutting most of its CSS and JavaScript.

We measured the ERP carefully before the change. On every integration since, the measurement after the change is part of the definition of done, so the improvement is on paper, not a feeling.

Laravel · PHP · ERP integration · Queues · Flutter