Most ERP integrations poll. Every few minutes, the WMS asks Acumatica what changed. It's simple to implement and works well enough — until the warehouse needs to act on data the moment it changes, not several minutes later.

WMSi uses Acumatica's push notification system instead. When a Purchase Order is updated, a Shipment is confirmed, or an inventory adjustment is posted, Acumatica sends the data to WMSi immediately. No polling loop. No lag.

How Acumatica push notifications work

Acumatica's push notification system is configured around Generic Inquiries — custom data views that define exactly what fields get sent and under what conditions. WMSi maintains a set of these GIs covering Purchase Orders, Stock Items, Shipments, Sales Orders, Assembly Orders, and inventory adjustments. Each one has a dedicated webhook endpoint in WMSi and a separate API key for authentication.

When a trigger field changes — a PO status, a shipment modification, an item master update — Acumatica fires the configured GI payload to WMSi's endpoint. WMSi receives it, queues it for async processing via Celery, and updates its internal data model within seconds.

The insert/delete pair problem

One non-obvious aspect of Acumatica's webhook behavior is how it signals changes. Rather than sending a single "record updated" event, Acumatica sends the previous state as a Deleted record and the new state as an Inserted record — sometimes in separate HTTP requests.

WMSi uses a short Redis cache window to coordinate these pairs. When a Deleted payload arrives, WMSi holds it briefly. If a matching Inserted payload arrives within that window, the two are processed together as a single update. This prevents false deletions from triggering incorrect downstream actions — a subtle failure mode that's easy to miss until it causes problems in production.

What gets synced

Every major data type the warehouse acts on arrives via push notification: purchase orders drive the receiving workflow, sales orders and shipments drive fulfillment, item master changes keep product data current without manual imports, and inventory adjustments feed the cycle count reconciliation process.

The result is a warehouse that operates on live ERP data — not a snapshot from the last polling cycle.

For VARs evaluating WMS integrations, the difference between polling and push notification becomes most visible under load, when orders are moving fast and the cost of stale data is highest.