Automating the Mapping

The average enterprise rewrite takes 18 months, yet 70% of these projects will fail before they reach production. The primary reason isn't a lack of talent or budget; it’s the "archaeology" problem. Most legacy systems are black boxes where the original developers are gone, the documentation is non-existent, and the business logic is buried under layers of technical debt.

When you decide to modernize, the first six months are typically spent in "Discovery"—manual sessions where architects try to map out what the system actually does. This is a manual, error-prone process that consumes 40 hours per screen on average.

We are moving past the era of manual audits. The future of enterprise modernization lies in automating the mapping through visual reverse engineering.

TL;DR: Automating the mapping of legacy workflows using visual reverse engineering reduces discovery and documentation time by 70%, transforming "black box" systems into documented, modern React codebases in weeks rather than years.

The $3.6 Trillion Documentation Gap#

Global technical debt has ballooned to an estimated $3.6 trillion. For a CTO in Financial Services or Healthcare, this isn't an abstract number—it’s the reason your team can't ship new features.

The core issue is that 67% of legacy systems lack any form of reliable documentation. When you attempt a "Big Bang" rewrite, you are essentially guessing at the business requirements. You end up rebuilding the bugs of the old system while missing the edge cases that kept the business running for twenty years.

The Cost of Manual Mapping#

In a traditional modernization project, the "Mapping" phase involves:

1. •Developers reading through thousands of lines of undocumented jQuery or COBOL.
2. •Product owners trying to remember why a specific "if" statement exists.
3. •Architects manually drawing diagrams in Lucidchart that are obsolete the moment they are finished.

Automating the Mapping: A New Paradigm#

Instead of performing code forensics, Replay treats the user interface as the source of truth. By recording real user workflows, the platform performs visual reverse engineering to extract the underlying architecture, state transitions, and component hierarchy.

This shift from "Code-First Discovery" to "Workflow-First Extraction" is how enterprises are finally breaking the 18-month rewrite cycle.

Step 1: Recording the Source of Truth#

The first step in automating the mapping is capturing the application in motion. Unlike static code analysis, which only shows you what the code could do, visual recording shows you what the code actually does.

In a regulated environment (SOC2/HIPAA), this is done via a secure recorder that captures the DOM mutations, network requests, and state changes.

Step 2: Extracting the Component Architecture#

Once a workflow is recorded, Replay’s AI Automation Suite analyzes the recording to identify patterns. It maps out the visual elements and groups them into logical, reusable React components.

typescript
// Example: Automated Mapping Output
// Replay identifies a legacy table and maps it to a modern shadcn/ui structure
import { useTable } from "@/hooks/use-legacy-bridge";

export function LegacyAccountTable({ rawData }) {
  // Automating the mapping of legacy data keys to modern types
  const { columns, rows } = useTable(rawData, {
    mapHeaders: true,
    preserveBusinessLogic: true
  });

  return (
    <div className="modern-container">
      <DataTable columns={columns} data={rows} />
    </div>
  );
}

💡 Pro Tip: Don't try to map the entire monolith at once. Use the "Strangler Fig" approach by recording high-value workflows first (e.g., "Claims Processing" or "User Onboarding") and automating the mapping for those specific modules.

Step 3: Generating API Contracts and Documentation#

One of the biggest pain points in modernization is the "Middle Tier." How does the UI talk to the legacy backend?

By automating the mapping of network traffic during the recording phase, Replay generates Swagger/OpenAPI specifications automatically. This eliminates the need for manual API discovery.

json
{
  "path": "/api/v1/legacy/process-order",
  "method": "POST",
  "generated_contract": {
    "request": {
      "orderId": "string",
      "timestamp": "iso8601",
      "payload": "object"
    },
    "observed_logic": "Validates checksum before processing"
  }
}

The "Black Box" to "Documented Codebase" Workflow#

To successfully automate the mapping of an enterprise system, follow this technical roadmap.

1. Assessment and Recording#

Identify the target screens. In a manufacturing or telecom environment, this might be a legacy ERP interface. Record the "Happy Path" and the "Error Paths." Replay captures every state change, ensuring that the "hidden" logic—the stuff that isn't in the documentation—is mapped.

2. Library Synthesis (The Design System)#

Replay takes the visual data and populates the Library. This is your modern Design System. Instead of manually building a button component to match the legacy style, the platform extracts the CSS, accessibility attributes, and functional properties.

3. Blueprint Generation#

The Blueprints editor allows architects to refine the automated mapping. You can see the legacy screen side-by-side with the generated React code.

⚠️ Warning: Never trust a 100% automated rewrite. Use the Blueprint editor to verify that complex business calculations (like interest rates or medical dosages) are mapped correctly from the legacy event handlers.

4. E2E Test Extraction#

Automating the mapping isn't just about code; it's about validation. Replay generates Playwright or Cypress tests based on the recorded workflows. This ensures that the new system behaves exactly like the old one, providing a "Safety Net" for the migration.

💰 ROI Insight: Companies using Replay save an average of $450,000 in developer salaries during the discovery phase alone by replacing manual documentation with automated extraction.

Case Study: Financial Services Modernization#

A Tier-1 bank had a 20-year-old commercial lending portal. The original team had retired, and the documentation was a 400-page PDF from 2008.

• •The Challenge: Map 150 unique screens and 40 complex workflows.
• •The Manual Estimate: 14 months, $1.2M.
• •The Replay Solution: By automating the mapping through visual reverse engineering, the team recorded all 40 workflows in two weeks.
• •The Result: Replay generated 85% of the React components and 100% of the API contracts. The project moved to UAT in 3 months.

Why "Big Bang" Rewrites are Obsolete#

The "Big Bang" rewrite fails because it assumes you can freeze the business for two years while you "figure out" the old system. In reality, the business keeps evolving.

Automating the mapping allows for Incremental Modernization. You can extract a single flow, modernize it, and run it in parallel with the legacy system. This is the "Strangler Fig" pattern powered by automation.

• •Visual Truth: Video doesn't lie; code comments do.
• •Technical Debt Audit: Replay identifies which parts of the legacy code are actually being used by users, allowing you to delete "dead" code rather than migrating it.
• •Rapid Prototyping: Go from a legacy screen to a functional React prototype in hours.

Frequently Asked Questions#

How does automating the mapping handle complex business logic?#

Replay captures the state transitions and network payloads during a live session. While it extracts the UI components automatically, it also flags complex event handlers for architectural review in the Blueprints editor, ensuring that critical logic is never "guessed" by the AI.

Does Replay work with mainframe-backed systems?#

Yes. Because Replay operates at the presentation layer (Visual Reverse Engineering), it doesn't matter if your backend is COBOL, Java, or .NET. If it renders in a browser or a terminal emulator, we can map it.

What is the typical time savings?#

On average, our enterprise partners see a 70% reduction in total project time. The most significant savings occur in the Discovery and UI Development phases, where 40 hours of manual work is reduced to roughly 4 hours of automated extraction and refinement.

Is the generated code maintainable?#

Unlike "low-code" platforms that output spaghetti code, Replay generates clean, typed React components that follow your team's specific coding standards. It integrates with your existing Design System and CI/CD pipeline.

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