Warehousing and eCommerce operate at different speeds. Your WMS tracks physical inventory — pick, pack, ship, receive — while Magento needs accurate stock counts to prevent overselling. Connecting these two systems requires careful design of sync frequency, conflict resolution, and error recovery.
Event-Driven vs. Polling Architecture
Most WMS systems support webhooks or event-based notifications for inventory changes. Use this instead of polling — polling every 5 minutes means you're always up to 5 minutes behind, and polling creates unnecessary load on both systems. If your WMS doesn't support webhooks, implement a change-data-capture (CDC) approach reading from the WMS database's transaction log.
Idempotency: The Critical Design Requirement
Every sync operation must be idempotent — running it twice should produce the same result as running it once. This is essential for retry logic. Include an idempotency key (usually a combination of WMS event ID and timestamp) in every API call. On the Magento side, check if the inventory update has already been applied before processing.
Handling the Oversell Problem
Even with real-time sync, there's a window between WMS inventory adjustment and Magento stock update where overselling can occur. Mitigation strategies: maintain a safety stock buffer in Magento (hold back 5-10% of physical stock), use Magento MSI's 'notify quantity' threshold to stop selling before stock hits zero, and implement pre-order logic for popular items.
Reconciliation Jobs
Even the best real-time sync will occasionally drift due to network errors, system restarts, or edge cases. Run a nightly reconciliation job that compares WMS stock quantities against Magento stock quantities and flags discrepancies above a threshold. Investigate discrepancies; don't automatically overwrite — you need to understand why they occurred to prevent them from recurring.
