Natural to React Modernization: Recovering 30 Years of Actuarial Logic in Life Insurance

The $3.6 trillion global technical debt crisis isn't just an IT line item; for life insurance providers, it is an existential threat. In the actuarial departments of the world’s largest carriers, 30 years of mission-critical risk logic is currently trapped inside Software AG Natural environments running on aging mainframes. These systems are "black boxes"—the original architects have retired, the documentation is non-existent (67% of legacy systems lack any formal documentation), and the cost of a "Big Bang" rewrite is a death sentence for most projects.

History is littered with failed modernization attempts. 70% of legacy rewrites fail or significantly exceed their timelines, often because the business logic is so deeply intertwined with the legacy UI that it cannot be decoupled through traditional "archaeology."

TL;DR: Natural react modernization no longer requires a 24-month manual rewrite; by using visual reverse engineering with Replay, enterprises can extract legacy actuarial logic into documented React components and API contracts in weeks, reducing modernization timelines by 70%.

The "Archaeology" Trap: Why Manual Natural to React Modernization Fails#

Traditional modernization projects follow a predictable, painful path. A team of consultants spends six months "discovering" the system. They attempt to read through thousands of lines of Natural code, trying to map

statements and calls to modern business requirements.

This manual approach takes an average of 40 hours per screen just to document and prototype. In a typical insurance suite with 500+ screens, you are looking at years of work before a single line of production-ready React code is written.

The Cost of Discovery#

The primary bottleneck in natural react modernization is the "knowledge gap." When the logic for a whole-life insurance premium calculation was written in 1994, it wasn't just code—it was a reflection of the regulatory and actuarial environment of that era.

⚠️ Warning: Attempting to rewrite actuarial logic from code alone—without observing the live state of the data during user workflows—frequently leads to "logic drift" where the new system fails to match the legacy system's calculations.

From Black Box to React: The Power of Visual Reverse Engineering#

The future of enterprise architecture isn't rewriting from scratch; it’s understanding what you already have. Replay shifts the paradigm from "code archaeology" to "visual reverse engineering." Instead of reading dead code, Replay records real user workflows within the legacy Natural environment.

By capturing the "source of truth"—the actual interaction between the user and the mainframe—Replay identifies the exact business logic required to replicate the screen in React. It maps the inputs, the state transitions, and the resulting actuarial outputs.

Preserving Actuarial Integrity#

In life insurance, the "how" is just as important as the "what." If a legacy Natural screen handles a complex dividend calculation, Replay doesn't just look at the UI; it extracts the underlying data patterns. This allows architects to generate modern API contracts that mirror the legacy system's behavior perfectly.

typescript
// Example: Generated React Component from Replay Extraction
// This component preserves the complex actuarial input logic 
// identified during the Natural session recording.

import React, { useState, useEffect } from 'react';
import { ActuarialProvider, PremiumCalculator } from '@insurance-core/logic';
import { LegacyInput, ModernButton, ValidationAlert } from './ui-library';

interface ActuarialProps {
  policyId: string;
  legacyState: any; // Captured from Replay session
}

export const PremiumAdjustmentForm: React.FC<ActuarialProps> = ({ policyId, legacyState }) => {
  const [premiumData, setPremiumData] = useState(legacyState.defaults);
  const [isValid, setIsValid] = useState(true);

  // Business logic preserved from legacy Natural "PERFORM CALC-PREMIUM"
  const handleCalculation = async (values: any) => {
    const result = await PremiumCalculator.calculate(values);
    if (result.variance > 0.05) {
      setIsValid(false); // Flagging variance from legacy baseline
    }
    setPremiumData(result);
  };

  return (
    <div className="p-6 bg-white rounded-lg shadow-md">
      <h2 className="text-xl font-bold mb-4">Actuarial Premium Adjustment</h2>
      <LegacyInput 
        label="Current Dividend Rate" 
        value={premiumData.dividendRate} 
        onChange={(v) => handleCalculation({...premiumData, dividendRate: v})}
      />
      {!isValid && <ValidationAlert message="Calculation deviates from legacy baseline." />}
      <ModernButton onClick={() => console.log('Submit to API')}>
        Update Policy
      </ModernButton>
    </div>
  );
};

The 3-Step Framework for Natural React Modernization#

Modernizing a 30-year-old system doesn't have to be a multi-year slog. By using Replay’s AI Automation Suite, the process is compressed from months into days.

Step 1: Assessment and Recording#

Instead of interviewing retired developers, your current subject matter experts (SMEs) simply perform their daily tasks. Replay records these workflows, capturing the "Flows" (Architecture) and the underlying data structures. This turns the black box into a documented map of the system.

Step 2: Extraction and Blueprinting#

Replay’s "Blueprints" editor takes the recorded session and automatically identifies UI patterns. It maps Natural terminal fields to modern React components. If the legacy system has a specific way of handling "Mortality Table" lookups, Replay identifies that logic pattern and generates the corresponding API contract.

Step 3: Generation and Technical Debt Audit#

The platform generates production-ready React code, E2E tests, and comprehensive documentation. Crucially, it performs a Technical Debt Audit, identifying which parts of the legacy logic are redundant and which are critical for the natural react modernization effort.

💰 ROI Insight: Manual modernization costs average $15,000 - $25,000 per screen in developer hours and lost productivity. Replay reduces this to approximately $2,500 per screen by automating the discovery and scaffolding phases.

Addressing the "Regulated Environment" Elephant in the Room#

For CTOs in Insurance and Healthcare, "cloud-only" is often a non-starter. Legacy systems are often tied to On-Premise mainframes due to strict data residency and SOC2/HIPAA requirements.

Replay is built for these environments. It offers an On-Premise deployment model that ensures your actuarial logic and PII (Personally Identifiable Information) never leave your secure perimeter. You get the speed of AI-driven modernization without the security risks of public LLM exposure.

Technical Debt: The $3.6 Trillion Problem#

Every year you wait to modernize, your technical debt accrues interest. The "Natural" talent pool is shrinking. By the time you decide to move, there may be no one left who understands the original code. Natural react modernization is not just about a prettier UI; it's about data sovereignty and operational continuity.

typescript
// Example: Generated API Contract for Legacy Integration
// Replay identifies the necessary endpoints to bridge React to Adabas/Natural

export interface PolicyModernizationContract {
  /**
   * Maps to Natural Map: PRM-001
   * Legacy Transaction Code: UPDT
   */
  updatePremium: {
    request: {
      policyNumber: string; // ADABAS Field: AA
      effectiveDate: number; // ADABAS Field: AB
      riskCategory: 'Low' | 'Medium' | 'High'; // Extracted from validation logic
    };
    response: {
      newPremium: number;
      actuarialVariance: number;
      status: 'SUCCESS' | 'PENDING_REVIEW';
    };
  };
}

Moving Beyond the "Screen Scraper" Mentality#

Earlier attempts at modernization relied on "screen scraping"—simply putting a web wrapper around a terminal. This is a stopgap, not a solution. It leaves the technical debt intact.

True natural react modernization involves extracting the logic so it can run independently of the mainframe. Replay’s Library (Design System) feature ensures that as you extract these components, they adhere to your enterprise’s modern design standards, creating a seamless experience for the end-user while the backend is incrementally migrated.

Why Visual Reverse Engineering is the "Source of Truth"#

Code can lie. Documentation can be outdated. But a user workflow is a factual record of how the business operates. By using video as the source of truth, Replay ensures that the React application behaves exactly as the business requires, catching the "edge cases" that manual documentation misses.

• •70% average time savings compared to manual rewrites.
• •From 18-24 months to days/weeks for initial MVP.
• •SOC2 and HIPAA-ready for regulated life insurance environments.

Frequently Asked Questions#

How long does a typical Natural to React modernization take with Replay?#

While a manual rewrite of a complex insurance module can take 12-18 months, Replay users typically see a fully documented and scaffolded React environment within 4 to 8 weeks. The actual "recording" of workflows takes only hours, while the AI-assisted extraction and logic mapping take a few weeks.

Does Replay require access to our mainframe source code?#

No. Replay uses Visual Reverse Engineering. It learns from the user interactions and the system's responses. While having source code can be helpful for cross-referencing, Replay’s primary "source of truth" is the live workflow, making it ideal for systems where the source code is lost or poorly documented.

What about complex actuarial business logic?#

Replay captures the relationship between inputs and outputs. If a specific input in a Natural screen triggers a complex calculation, Replay identifies the data pattern and generates the necessary API contracts and frontend validation logic to replicate that behavior in React.

Is the generated React code maintainable?#

Yes. Unlike "black box" low-code tools, Replay generates standard, high-quality React/TypeScript code that your developers can own, modify, and maintain. It follows your organization's specific Design System and coding standards.

How does Replay handle security in regulated industries?#

Replay is built for the Enterprise. We offer On-Premise installation options, ensuring that sensitive insurance data never leaves your network. We are SOC2 compliant and the platform is designed to be HIPAA-ready.

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