Invisible Infrastructure: Mapping the Undocumented Connections in 20-Year-Old Middleware

Your most critical business logic is currently running on infrastructure that no one in your building understands. It is a 20-year-old middleware stack—perhaps a mix of Tibco, IBM MQ, or a custom-built SOAP layer—that has become a "black box" through two decades of developer turnover and undocumented hotfixes. This is the reality of the $3.6 trillion global technical debt: we are not building on solid ground; we are building on invisible infrastructure.

TL;DR: Invisible infrastructure mapping via visual reverse engineering replaces months of manual "code archaeology" with automated documentation, reducing modernization timelines from years to weeks.

The Archaeology Trap: Why 70% of Legacy Rewrites Fail#

The standard approach to legacy modernization is flawed from the start. When a CTO mandates a "Big Bang" rewrite, the engineering team immediately hits a wall: the documentation gap. Statistics show that 67% of legacy systems lack any form of accurate documentation. This forces senior architects into a role they never signed up for: digital archaeologists.

They spend months digging through brittle COBOL or Java 1.4 codebases, trying to map dependencies that aren't even defined in the code, but in the runtime behavior of the middleware. This manual discovery process is the primary reason why 70% of legacy rewrites fail or significantly exceed their timelines.

In a traditional manual audit, it takes an average of 40 hours per screen to document the business logic, data flow, and API requirements. For an enterprise application with 200 screens, that’s 8,000 man-hours before a single line of modern React code is even written.

The Cost of the "Black Box"#

When infrastructure is invisible, every change is a risk. You don't know if updating a field in a legacy database will break a downstream reporting service that hasn't been touched since 2008. This fear leads to "ossification," where the system becomes too scary to change, and the business loses its competitive edge.

⚠️ Warning: Attempting a "Big Bang" rewrite without a complete map of your invisible infrastructure is the leading cause of multi-million dollar project cancellations in the Fortune 500.

Invisible Infrastructure Mapping: A New Paradigm#

The future of modernization isn't rewriting from scratch; it’s understanding what you already have. This is where invisible infrastructure mapping changes the ROI equation. Instead of reading dead code, we record live execution.

By using Replay, enterprises can record real user workflows. These recordings serve as the "source of truth" for reverse engineering. The platform observes the interactions between the frontend, the middleware, and the database in real-time, effectively "lighting up" the invisible connections that manual audits miss.

Comparison of Modernization Approaches#

From Video to React: The Technical Extraction Process#

The core innovation of Replay is the ability to transform a recording into a documented, functional React component and its associated API contracts. This isn't "low-code" fluff; it is high-fidelity technical extraction designed for Senior Architects.

When a user interacts with a legacy middleware-driven screen, Replay captures the DOM state, the network requests, and the underlying business logic triggers. The AI Automation Suite then processes this data to generate clean, typed code.

Example: Generated API Contract from Legacy SOAP Middleware#

In many 20-year-old systems, the middleware communicates via complex, undocumented XML/SOAP envelopes. Replay maps these to modern REST or GraphQL contracts automatically.

typescript
/**
 * Generated by Replay AI - Legacy Middleware Mapping
 * Source: Insurance_Claims_v2_Final_FINAL.wsdl (Legacy)
 * Target: Claims Management Microservice
 */

export interface ClaimSubmissionRequest {
  claimId: string; // Extracted from hidden field ID_04
  policyNumber: string; // Mapped from legacy 'POL_REF'
  incidentDate: ISO8601String; 
  claimantDetails: {
    firstName: string;
    lastName: string;
    taxId: string; // Encrypted in transit
  };
  // Business Logic Note: Field 'Status' must be 'PENDING' for all new submissions
  status: "PENDING" | "SUBMITTED" | "REJECTED";
}

export async function submitClaim(data: ClaimSubmissionRequest): Promise<void> {
  // Replay generated the fetch wrapper with proper headers for legacy auth
  return await api.post('/api/v1/claims', data);
}

Example: Migrated React Component#

The platform doesn't just give you the data; it gives you the UI. It extracts the layout and logic from the legacy screen and maps it to your modern Design System.

tsx
import React, { useState } from 'react';
import { Button, Input, Card } from '@your-org/design-system';

// Replay extracted this logic from a 2004-era ASP.NET postback
export const LegacyClaimFormMigrated = () => {
  const [formData, setFormData] = useState<Partial<ClaimSubmissionRequest>>({});

  const handleValidation = () => {
    // Replay identified this specific regex from the legacy client-side script
    const taxIdRegex = /^\d{3}-\d{2}-\d{4}$/;
    return taxIdRegex.test(formData.taxId || '');
  };

  return (
    <Card title="Submit New Claim">
      <Input 
        label="Policy Number" 
        onChange={(v) => setFormData({...formData, policyNumber: v})} 
      />
      <Input 
        label="Social Security Number" 
        error={!handleValidation() ? "Invalid Format" : undefined}
        onChange={(v) => setFormData({...formData, taxId: v})} 
      />
      <Button onClick={() => console.log("Submitting...", formData)}>
        Submit Claim
      </Button>
    </Card>
  );
};

💰 ROI Insight: By automating the extraction of these components and contracts, Replay reduces the time spent per screen from 40 hours to just 4 hours. In a 100-screen project, this saves 3,600 engineering hours—roughly $540,000 in developer costs alone.

3 Steps to Map Your Invisible Infrastructure#

Modernizing a 20-year-old system doesn't have to be a journey into the unknown. We follow a structured technical protocol to move from a black box to a documented codebase.

Step 1: Visual Recording & Flow Capture#

Instead of reading the source code, we use Replay to record subject matter experts (SMEs) performing standard business tasks. This captures the system in its "natural habitat," documenting how the middleware actually behaves when pushed, not how the 2004 README says it should behave.

Step 2: Automated Component Extraction#

The Replay AI Automation Suite analyzes the recording. It identifies recurring UI patterns and groups them into a "Library" (your new Design System). It simultaneously maps every network interaction to create a "Blueprints" library—a visual architecture of your middleware's invisible connections.

Step 3: Technical Debt Audit & E2E Generation#

Finally, the platform generates a comprehensive Technical Debt Audit. It identifies dead code paths (features that exist in the UI but are never used in recordings) and generates E2E tests (Playwright/Cypress) that ensure the new system matches the legacy system's behavior bit-for-bit.

💡 Pro Tip: Use the generated E2E tests as a "safety net" during the migration. If the new React component passes the test suite recorded from the legacy system, you have mathematical proof of parity.

Built for Regulated Environments#

For architects in Financial Services, Healthcare, and Government, "cloud-only" tools are often a non-starter. Invisible infrastructure mapping often involves sensitive PII (Personally Identifiable Information) or PHI (Protected Health Information).

Replay was built with these constraints in mind:

• •SOC2 & HIPAA Ready: Data handling meets the highest security standards.
• •On-Premise Deployment: Run the entire extraction engine within your own VPC or data center.
• •PII Masking: Automatically redact sensitive data during the recording and extraction process.

The Future: From Archaeology to Engineering#

The $3.6 trillion technical debt problem won't be solved by hiring more developers to write more code. It will be solved by understanding the code we already have.

When you map your invisible infrastructure, you stop guessing. You stop the cycle of failed 18-month rewrites. You move from a state of "archaeology"—digging through the past—to a state of "engineering"—building the future.

Replay provides the flashlight for the black box, turning undocumented middleware into a clean, documented, and modern React-based ecosystem in a fraction of the time.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a manual audit takes 18–24 months for an enterprise-scale application, Replay typically completes the mapping and extraction phase in 2–8 weeks. The specific timeline depends on the number of unique user flows, but the 70% time savings remains consistent across industries.

What about business logic preservation?#

This is the most common concern. Replay captures the behavioral logic—the "if/then" scenarios that actually happen during execution. By generating E2E tests from the legacy recording, we ensure that the modern version of the application preserves 100% of the business-critical logic, even if that logic was originally buried in an undocumented stored procedure.

Does Replay require access to the original source code?#

No. Replay works by observing the application at runtime (Visual Reverse Engineering). This is particularly valuable for systems where the source code is lost, obfuscated, or written in languages that modern developers cannot easily parse.

Can Replay handle mainframe or terminal-based middleware?#

Yes. As long as there is a web-based or desktop-based frontend that interacts with the middleware, Replay can record the interactions and map the underlying API calls and data structures.

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