Modernizing Supply Chain Visibility: Extracting Logic from Legacy WMS

70% of legacy rewrites fail or exceed their timeline because organizations attempt to rebuild what they don't fully understand. In the high-stakes world of logistics, a failed Warehouse Management System (WMS) migration doesn't just result in a missed deadline—it halts shipments, depletes inventory visibility, and erodes customer trust.

TL;DR: Modernizing supply chain visibility requires moving from "manual archaeology" to visual reverse engineering, reducing modernization timelines from 18 months to weeks by extracting business logic directly from legacy workflows.

The High Cost of Supply Chain Stagnation#

The global supply chain is currently anchored by a $3.6 trillion technical debt. Most Tier-1 and Tier-2 providers are running on WMS architectures built two decades ago. These systems are "black boxes": the original developers are gone, the documentation is non-existent (67% of legacy systems lack any functional docs), and the business logic is buried under layers of spaghetti code.

When a VP of Engineering is tasked with modernizing supply chain visibility, they typically face a choice between three high-risk paths:

1. •The Big Bang Rewrite: Scrapping the old system for a new one. This takes an average of 18-24 months and has a 70% failure rate.
2. •The Strangler Fig: Slowly replacing modules. This is safer but often results in a decade-long "temporary" state of hybrid complexity.
3. •Manual Documentation: Sending engineers on an "archaeology" mission to read old code. This takes roughly 40 hours per screen just to map requirements.

The Comparison: Modernization Strategies#

💰 ROI Insight: Manual reverse engineering costs an average of 40 hours per screen. With Replay, this is reduced to 4 hours—a 90% reduction in engineering overhead.

Moving From Black Box to Documented Codebase#

The primary bottleneck in modernizing supply chain systems is the "Logic Gap." You cannot build a modern React-based visibility dashboard if you don't know the exact SQL triggers or COBOL routines that calculate "Available to Promise" (ATP) inventory.

Replay changes the unit of work from "reading code" to "recording reality." By recording a real user workflow—such as a warehouse manager processing a cross-dock shipment—Replay captures the DOM mutations, network calls, and state changes. It then uses AI to reverse engineer these into modern, documented React components and API contracts.

Technical Debt Audit: The Silent Killer#

Before writing a single line of new code, you must understand the depth of the hole you are in. A Technical Debt Audit in Replay identifies:

• •Dead code paths that users never actually touch.
• •Hardcoded business rules hidden in UI event handlers.
• •Redundant API calls that throttle legacy database performance.

⚠️ Warning: Proceeding with a rewrite without a technical debt audit leads to "feature parity traps," where you spend 30% of your budget rebuilding features that no one has used since 2014.

The Technical Blueprint: Extracting Logic#

When Replay processes a recorded session of a legacy WMS, it doesn't just take a screenshot. It analyzes the execution trace. It identifies the data structures being passed between the legacy frontend and the mainframe backend.

Example: Generated API Contract#

Replay automatically generates OpenAPI/Swagger specifications from legacy traffic. This allows your backend team to build modern microservices that match the legacy system's expected inputs exactly.

json
{
  "openapi": "3.0.0",
  "info": {
    "title": "Legacy WMS Inventory API",
    "version": "1.0.1"
  },
  "paths": {
    "/inv/v1/allocation": {
      "post": {
        "summary": "Extracted from 'Pick-and-Pack' Workflow",
        "parameters": [
          { "name": "whse_id", "in": "query", "required": true, "schema": { "type": "string" } },
          { "name": "sku_id", "in": "body", "required": true, "schema": { "type": "integer" } }
        ],
        "responses": {
          "200": { "description": "Successful allocation based on legacy routing logic" }
        }
      }
    }
  }
}

Example: Migrated React Component#

Replay's AI Automation Suite takes the recorded DOM and state transitions to generate a clean, modular React component. This isn't "spaghetti code" output; it’s structured for your modern Design System (Library).

typescript
// Example: Generated component from WMS video extraction
import React, { useState, useEffect } from 'react';
import { Button, Table, StatusBadge } from '@/design-system';

export function InventoryAllocationDashboard({ legacyData }) {
  const [allocation, setAllocation] = useState(legacyData);

  // Business logic preserved: ATP (Available to Promise) calculation
  const calculateATP = (qty, reserved) => {
    return qty - reserved > 0 ? qty - reserved : 0;
  };

  return (
    <div className="p-6 bg-white rounded-lg shadow">
      <h2 className="text-xl font-bold">WMS Allocation View</h2>
      <Table>
        <thead>
          <tr>
            <th>SKU</th>
            <th>On Hand</th>
            <th>ATP Status</th>
          </tr>
        </thead>
        <tbody>
          {allocation.map((item) => (
            <tr key={item.id}>
              <td>{item.sku}</td>
              <td>{item.quantity}</td>
              <td>
                <StatusBadge 
                  status={calculateATP(item.quantity, item.reserved) > 10 ? 'Healthy' : 'Low'} 
                />
              </td>
            </tr>
          ))}
        </tbody>
      </Table>
    </div>
  );
}

Step-by-Step: Modernizing Supply Chain Visibility with Replay#

Step 1: Record Workflows#

Instead of interviewing retired developers, have your power users perform their daily tasks—receiving, put-away, cycle counting—while Replay records the session. This becomes the "Video as source of truth."

Step 2: Visual Reverse Engineering#

Replay processes the recording, mapping the legacy UI elements to your modern design system. It identifies the "Flows" (Architecture) and creates a visual map of how data moves through the system.

Step 3: Blueprinting and Extraction#

Using the Blueprints (Editor), architects can refine the extracted logic. You can decide which legacy quirks to keep (e.g., specific tax rounding rules) and which to discard (e.g., 8-character field limitations).

Step 4: Automated E2E Test Generation#

Replay generates Playwright or Cypress tests based on the recorded legacy behavior. This ensures that your new system behaves exactly like the old one where it matters most, preventing regressions during the cutover.

💡 Pro Tip: Use Replay's "Flows" feature to visualize cross-departmental handoffs. Often, the "gap" in supply chain visibility isn't a lack of data, but a lack of understanding of how data transitions between the WMS and the TMS (Transportation Management System).

Built for Regulated Environments#

Supply chain systems often intersect with highly regulated data, especially in Healthcare (HIPAA) or Government (SOC2) logistics. Unlike generic AI tools that require sending code to the cloud, Replay offers:

• •On-Premise Deployment: Keep your proprietary logic and sensitive data within your firewall.
• •SOC2 & HIPAA Compliance: Ready for enterprise-grade security audits.
• •Audit Trails: See exactly how a piece of legacy logic was translated into a modern component.

Frequently Asked Questions#

How long does legacy extraction take?#

While a manual rewrite takes 18-24 months, a Replay-led modernization typically takes 2 to 8 weeks per core module. The initial "Visual Reverse Engineering" of a screen takes minutes; the refinement into a production-ready component takes a few hours.

What about business logic preservation?#

This is Replay’s core strength. Because we use "Video as source of truth," we capture how the system actually behaves, not just how the code is written. This catches the "shadow logic" and manual workarounds that developers often miss in traditional documentation phases.

Does Replay work with green-screen (Terminal) applications?#

Yes. Replay can record and extract logic from terminal emulators, Citrix-delivered apps, and older web frameworks (Silverlight, Flex, JSP) that are common in legacy supply chain environments.

Can we use our own Design System?#

Absolutely. Replay’s "Library" feature allows you to upload your own React/Tailwind components. The AI then maps the legacy functional elements to your specific UI library, ensuring the modernized system is on-brand and maintainable.

---

Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.