Ending the 6-Month Discovery Bottleneck: Mapping Complex Legacy Architectures in Under 14 Days

The most expensive part of your legacy migration isn’t the coding—it’s the archaeology. In the typical enterprise, 180 days are lost before a single line of production-ready code is written. This "Discovery Bottleneck" is where modernization projects go to die, consumed by manual documentation, lost source code, and the retirement of the only engineers who understood the original business logic.

TL;DR: By shifting from manual "software archaeology" to visual reverse engineering, enterprises can compress the 6-month discovery phase into a 14-day automated extraction process, reducing technical debt and modernization timelines by 70%.

The 6-Month Discovery Trap#

The industry standard for discovery is broken. When a Tier-1 bank or a national healthcare provider decides to modernize a legacy system, they typically assign a squad of business analysts and senior architects to "map the system." This involves:

1. •Interviewing Stakeholders: Attempting to reconstruct business rules from memory.
2. •Code Spelunking: Sifting through undocumented Java 6 or .NET 3.5 monoliths.
3. •Manual Mapping: Spending an average of 40 hours per screen to document UI state and API dependencies.

The result? By the time the discovery document is finished, it’s already obsolete. Statistics show that 67% of legacy systems lack any meaningful documentation, and 70% of legacy rewrites fail or exceed their timeline because the "source of truth" was a moving target.

The Cost of Manual Discovery#

Ending 6-Month Discovery: The Visual Reverse Engineering Shift#

The future of modernization isn't rewriting from scratch; it’s understanding what you already have by observing it in motion. Visual Reverse Engineering treats the running application as the ultimate source of truth. Instead of reading dead code, we record live workflows.

Replay captures the interaction between the user, the DOM, and the network layer. It doesn't just record a video; it records the state transitions, the data schemas, and the component hierarchy.

💰 ROI Insight: Replacing manual discovery with Replay saves an average of $250,000 in engineering hours for every 50 screens modernized, purely by eliminating the documentation phase.

Step 1: Workflow Recording (Days 1-3)#

Instead of architectural interviews, subject matter experts (SMEs) perform their standard tasks—processing a claim, opening a trade, or updating a patient record—while Replay records the session. This captures the "Shadow Logic" that never made it into the original requirements.

Step 2: Automated Component Extraction (Days 4-7)#

Replay’s AI Automation Suite analyzes the recording to identify patterns. It maps HTML elements to functional React components, identifying reusable patterns for your new Design System.

typescript
// Example: Replay-generated React component from a legacy JSP table
import React from 'react';
import { DataTable, Button } from '@your-org/design-system';

interface LegacyClaimRow {
  claimId: string;
  status: 'PENDING' | 'APPROVED' | 'REJECTED';
  amount: number;
}

/**
 * @generated Extracted from Workflow: "Claims Processing Alpha"
 * @source_legacy_path /admin/claims/view.jsp
 */
export const ClaimsTable: React.FC<{ data: LegacyClaimRow[] }> = ({ data }) => {
  const handleApprove = (id: string) => {
    // Logic preserved from legacy XHR intercept
    console.log(`Approving claim: ${id}`);
  };

  return (
    <DataTable
      columns={[
        { header: 'ID', accessor: 'claimId' },
        { header: 'Status', accessor: 'status' },
        { 
          header: 'Actions', 
          render: (row) => <Button onClick={() => handleApprove(row.claimId)}>Approve</Button> 
        }
      ]}
      data={data}
    />
  );
};

Step 3: API Contract Generation (Days 8-10)#

While the UI is being mapped, Replay’s Flows engine monitors the network traffic. It automatically generates OpenAPI (Swagger) specifications based on real-world payloads, not what the 10-year-old documentation says the API does.

⚠️ Warning: Relying on old Swagger files during a rewrite is a primary cause of integration failure. Always generate new contracts from live traffic to capture undocumented "quirks" in the legacy API.

Step 4: Technical Debt Audit & Blueprinting (Days 11-14)#

The final stage of ending 6-month discovery is the Blueprint. Replay synthesizes the extracted components, API contracts, and user flows into a technical roadmap. You move from "Black Box" to a documented codebase in under two weeks.

Architecture Mapping: From Black Box to React#

Modernizing complex legacy architectures—especially in regulated industries like Financial Services or Healthcare—requires more than just a UI facelift. You need to preserve the complex business logic buried in nested conditionals and legacy state management.

Preserving Business Logic#

Replay doesn't just "scrape" the UI. It maps the underlying state changes. If a legacy insurance form has 50 hidden fields that only trigger under specific regulatory conditions, Replay captures those state transitions during the recording phase.

typescript
// Generated Blueprint for a complex state transition
// Scenario: Medicare Part D Eligibility Check
export const useEligibilityLogic = (age: number, state: string) => {
  // Replay identified this logic from legacy 'checkEligibility.js'
  // and validated it against 15 recorded user sessions.
  const isEligible = React.useMemo(() => {
    if (state === 'NY' && age >= 65) return true;
    if (['CA', 'FL'].includes(state) && age >= 62) return true;
    return false;
  }, [age, state]);

  return { isEligible };
};

The AI Automation Suite#

The Replay AI doesn't just copy-paste; it refactors. It identifies redundant CSS, suggests modern hooks to replace legacy lifecycle methods, and flags potential security vulnerabilities in the legacy data flow.

• •Library (Design System): Automatically groups similar legacy elements into a unified React component library.
• •Flows (Architecture): Visualizes the sequence of API calls, identifying bottlenecks and N+1 query problems in the legacy backend.
• •Blueprints (Editor): Allows architects to tweak the generated code before it hits the repository.

💡 Pro Tip: Use the "Technical Debt Audit" feature in Replay to prioritize which modules to migrate first. Focus on high-usage, high-complexity screens to see the fastest ROI.

Why Big Bang Rewrites Fail (And How We Avoid It)#

The $3.6 trillion global technical debt isn't just a financial figure; it’s a graveyard of failed "Big Bang" rewrites. Enterprises attempt to move everything at once, only to realize 12 months in that they didn't understand the original system's complexity.

By ending 6-month discovery, you shift the risk profile. You can adopt a "Strangler Fig" approach with surgical precision because you have a complete map of the system.

• •Legacy System: Continues to run.
• •Replay: Extracts a specific workflow (e.g., "User Onboarding").
• •Modern System: The new React component is deployed, calling the same legacy APIs (verified by Replay-generated contracts).
• •Cutover: Once the new workflow is stable, you move to the next.

Built for the Regulated Enterprise#

We understand that in Government, Telecom, and Insurance, "cloud-only" isn't always an option. Replay is built for the constraints of the modern enterprise architect:

1. •SOC2 & HIPAA Ready: Data privacy is baked into the extraction process. Sensitive PII can be masked during the recording phase.
2. •On-Premise Available: For environments where data cannot leave the internal network, Replay can be deployed entirely on-premise.
3. •E2E Test Generation: Replay generates Cypress or Playwright tests based on the recorded workflows, ensuring that the modernized version behaves exactly like the legacy original.

📝 Note: Replay supports legacy systems ranging from mainframe-backed web portals to complex Silverlight and Flash-to-HTML5 migrations.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a traditional discovery phase takes 6-9 months, Replay typically delivers a full architectural map and initial component library in 10-14 days. The actual extraction of a single complex screen takes approximately 4 hours of automated processing vs. 40 hours of manual coding.

What about business logic preservation?#

Replay captures business logic by observing state changes and network payloads. While some complex server-side logic still requires backend refactoring, Replay provides the "API Contract" and "State Map" that backend teams need to ensure the new services match the legacy behavior 1:1.

Does Replay work with legacy frameworks like JSP, ASP.NET, or Delphi?#

Yes. If the application can be rendered in a browser or through a web-based terminal emulator, Replay can record the DOM transitions and network traffic to reverse engineer the frontend into modern React components.

How does this integrate with our existing CI/CD?#

Replay exports standard React code, TypeScript interfaces, and OpenAPI specs. This output can be pushed directly to your Git provider (GitHub, GitLab, Bitbucket) and integrated into your standard development workflow.

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