Retailer Achieved 90%+ Inventory Accuracy and 30–40% Faster Fulfilment With AS/400–Shopify Integration

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Retail warehouse and storefront operations connected by an integration layer

90%+

Inventory accuracy, up from the 80s

30–40%

Faster order-to-fulfilment processing

Zero

Manual order re-keying

Client Overview

The client is a North American specialty retail chain operating roughly 40 physical stores alongside a Shopify Plus web store. It carries about 120,000 active SKUs and takes around 3,000 online orders a week. It sells products in the home and hardware category, where customers expect accurate stock information and reliable fulfilment across both online and in-store channels.

Its storefront runs on Shopify Plus, a cloud commerce platform chosen for its speed, ease of management, and broad app and theme ecosystem. Behind the storefront, however, the business continues to depend on an on-premise AS/400 environment for inventory, pricing, SKU data, purchasing, point of sale, and warehouse management.

Business Challenges

  • Shopify and the AS/400 Ran on Separate Clocks

    Shopify received information from the AS/400 through a nightly batch extract. This meant the cloud storefront and the on-premise AS/400 were rarely working with the same information at the same time. Inventory, pricing, and product data displayed online were several hours out of date.

  • Shopify Accepted Orders for Items That Had Already Sold Out

    Because Shopify relied on an old inventory extract, it continued showing an item as available even after the final unit had already been sold in a store. Customers then placed online orders for products the retailer no longer had. This led to order cancellations, and lost sales.

  • Prices Reached the Storefront Too Late

    Price changes made in the AS/400 during the day did not reach Shopify until the nightly update. This meant products continued selling online at an old price for several hours, creating inconsistent pricing across channels and affecting margins.

  • Web Orders Were Re-Keyed by Hand

    Orders placed through Shopify had to be manually entered into the AS/400 before warehouse teams began fulfilment.

    This added delays, created duplicate work, and increased the risk of errors. The storefront looked modern to customers, but the connection back to the AS/400 still depended on manual work and overnight batch files.

Approaches Considered

Both Shopify Plus and the AS/400 were performing their core functions effectively.

The problem was not either platform. It was the way the cloud storefront and the on-premise AS/400 were connected. Two approaches were considered.

OPTION 01

Replace a Platform

Replacing the AS/400 would have meant rebuilding years of business logic, operational processes, and integrations. It would also have introduced risk into the system responsible for inventory, purchasing, warehouse operations, and transaction processing.

Replacing Shopify Plus made little sense because the storefront was already delivering the digital commerce experience the retailer needed.

Either replacement would have introduced significant cost and disruption to solve a problem that was not caused by the platforms themselves.

OPTION 02 - RECOMMENDED

Real-Time Event-Driven Integration

A hybrid integration layer would connect the on-premise AS/400 with Shopify Plus while keeping the AS/400 as the system of record.

Time-sensitive information, including orders, inventory changes, pricing, and important product updates, would move between the two platforms in near real time.

High-volume, non-urgent processes, including bulk catalog loads, reporting, and reconciliation, would continue running through scheduled batch jobs.

This approach kept the AS/400 in place, used the right integration method for each flow, and allowed the solution to be introduced gradually.

Solutions Implemented

  1. 01 / Integration Strategy

    Applied a Hybrid Integration Pattern

    Rather than forcing every type of data through the same integration method, the team matched each flow to the business need. Customer-facing and fulfilment-related information moved in near real time so Shopify Plus and the AS/400 stayed closely aligned.

    Large, non-urgent workloads continued to run through scheduled batch processes, reducing unnecessary pressure on the AS/400 and the integration layer. This hybrid pattern allowed the storefront to stay current without changing the AS/400 applications that already supported the business.

  2. 02 / Real-Time Sync

    Real-Time, Event-Driven Sync for Live Data

    Shopify Plus was configured to send a webhook the moment an order was placed. The integration layer picked up that event, validated the order details, and called the AS/400's existing order-entry programs, which were made available to it as callable services.

    Those programs ran their usual checks, reserved the stock, applied the correct price and tax, and wrote the order into the AS/400 themselves. No order was keyed in by hand, and none reached the AS/400 without passing the checks it already applied to every other order. Inventory, price, and product lookups were served by read-only queries against the AS/400 database, since reading changes nothing. In the other direction, inventory, pricing, and product updates in the AS/400 were published to Shopify through the Shopify Admin API. The storefront saw stock move as stores and warehouses sold, and the AS/400 saw online orders as they consumed availability.

  3. 03 / Batch & Reconciliation

    Scheduled Batch for Bulk Loads and Reconciliation

    The team did not remove batch processing completely. Large catalog updates, bulk price files, reporting extracts, and other high-volume workloads continued to run as scheduled jobs. Processing these records together was more efficient than sending every record as an individual event.

    A nightly reconciliation process also compared information in Shopify Plus with the AS/400. Any difference in inventory, pricing, product information, or order status was flagged for review. This allowed the retailer to identify failed or delayed transactions before they became larger operational problems.

  4. 04 / Data Ownership

    Set a Clear Data-Ownership Map

    Before information began moving between the platforms, the team defined which system controlled each type of data. The AS/400 remained responsible for price, cost, inventory, SKU information, purchasing, warehouse transactions, and the final order record. Shopify Plus remained responsible for storefront content, online customer accounts, shopping carts, and the customer-facing web experience. This prevented the two platforms from making conflicting changes to the same fields.

    Clear data ownership was essential because two systems repeatedly overwriting each other would have recreated the same accuracy problems the integration was designed to solve.

  5. 05 / Integration Method

    Chose Connector or Custom Integration by Field Complexity

    Standard product, pricing, inventory, and order flows could be handled through established Shopify and AS/400 integration patterns. More complex fields required additional logic, particularly where the AS/400 contained customer-specific pricing, product restrictions, fulfilment rules, or custom SKU structures.

    The integration method was therefore chosen based on the complexity of the retailer's actual business rules rather than applying the same connector to every requirement.

Implementation Roadmap

  1. Discovery and Data-Ownership Mapping

    The team reviewed the Db2 for i tables, field structures, current batch files, and operational processes. They identified which flows needed near-real-time integration and which could continue running as scheduled batch jobs. Ownership rules were agreed upon before any data began moving between Shopify Plus and the AS/400.

  2. Hybrid Integration Layer in a Pilot Region

    The integration layer was introduced in a controlled pilot region. Real-time event processing and scheduled batch jobs ran side by side. The existing nightly process remained available as a temporary safety measure while the team tested accuracy and reliability.

  3. Real-Time Order Write-Back and Live Pricing

    Shopify orders were automatically written into the AS/400, removing manual order re-keying. Pricing changes from the AS/400 also began reaching Shopify Plus faster, reducing the risk of customers seeing outdated prices.

  4. Batch Reconciliation and Bulk Catalog Processing

    Scheduled batch jobs were retained for bulk catalog updates and large pricing files. A nightly reconciliation process was added to identify differences between Shopify Plus and the AS/400 and flag them for review.

  5. Omnichannel and Multi-Region Rollout

    Once the pilot had proven stable, the integration was expanded across additional locations and fulfilment processes.

    Pickup-in-store, ship-from-store, reporting, and wider omnichannel services were added using the more current inventory and order information. The AS/400 core remained in place throughout the rollout.

Business Impact

80s% → 90s%

Inventory accuracy

30–40%

Faster order-to-fulfilment processing

Zero

Manual order re-keying

~20%

Less excess and safety stock

Looking Ahead

The hybrid integration layer gave the retailer a foundation for adding loyalty programs, marketplace feeds, store-level fulfilment, supplier integrations, and customer notifications. New real-time and batch flows can now be introduced as the business grows, while the AS/400 continues to support core operations.

Nalashaa continues to support the AS/400 environment and guide future integration and modernization initiatives.

“For years, our website and our stores gave customers different answers. Once Shopify Plus and the AS/400 were connected, both channels began working with the same information. We reduced orders for unavailable products, removed manual order entry, and improved fulfilment without replacing the AS/400 that runs our core operations.”
— VP of eCommerce, North American specialty retail chain

Ready to connect your AS/400 to the cloud without replacing it?

Nalashaa builds hybrid real-time and batch integrations between IBM i and platforms such as Shopify Plus, keeping the AS/400 as the system of record while the storefront moves at retail speed.

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