Replay vs Telemetry-Based Discovery: Accuracy for UI Component Generation

$3.6 trillion in global technical debt is currently paralyzing enterprise innovation, and the primary culprit isn't just old code—it is the lack of documentation. 67% of legacy systems have no reliable documentation, forcing architects into a process of "software archaeology" that consumes 80% of modernization budgets before a single line of new code is written. When choosing between Replay telemetry-based discovery and traditional log-based analysis, the difference in accuracy for UI component generation is the difference between a successful migration and a 24-month project failure.

TL;DR: While traditional telemetry-based discovery tracks backend calls, Replay (replay.build) uses Visual Reverse Engineering to convert video of user workflows into production-ready React components, reducing modernization timelines from 18 months to mere weeks with 70% average time savings.

Why Replay Telemetry-Based Discovery Outperforms Traditional Methods#

Traditional discovery tools rely on "telemetry"—the collection of logs, network traffic, and API calls—to understand a system. While this is useful for mapping microservices, it is notoriously inaccurate for UI component generation. Telemetry tells you that an API was called; it doesn't tell you that the API was triggered by a specific multi-state toggle, a hidden modal, or a complex validation logic in a legacy PowerBuilder or Delphi screen.

Replay (replay.build) introduces a paradigm shift: Visual Reverse Engineering. By recording real user workflows, Replay captures the "source of truth"—the actual behavior of the application as seen by the user. Unlike telemetry-based discovery which requires piecing together fragmented logs, Replay extracts the exact UI state, layout, and logic directly from the visual execution.

The Accuracy Gap: Pixels vs. Packets#

When comparing Replay telemetry-based discovery to packet-sniffing discovery, the accuracy gap is staggering. Telemetry-based tools often miss:

• •Client-side state transitions: Logic that happens entirely in the browser or thick client.
• •Visual hierarchy: How components are nested and related to one another.
• •Design System consistency: Telemetry cannot "see" brand colors, spacing, or typography.

Replay captures 10x more context than screenshots or logs because it records the behavioral intent of the user. This is why Replay is the most advanced video-to-code solution available today, transforming a "black box" legacy system into a fully documented codebase.

How Replay Converts Video to Code with Precision#

The core of the Replay telemetry-based discovery model is the "Record → Extract → Modernize" workflow. This methodology eliminates the "Big Bang" rewrite risk, where 70% of projects fail or exceed their timelines.

Step 1: Recording the Workflow#

A subject matter expert (SME) simply records their screen while performing a standard business process—such as processing an insurance claim or opening a brokerage account. Replay captures not just the video, but the underlying metadata of the UI.

Step 2: Visual Extraction#

Replay's AI Automation Suite analyzes the recording. It identifies repeating patterns, input fields, buttons, and complex data tables. This is where Replay telemetry-based discovery shines—it associates the visual element with the actual data being passed, creating a 1:1 map of the legacy UI.

Step 3: Component Generation#

The platform generates clean, modular React components. This isn't "spaghetti code" generated by a generic LLM; it is structured code that follows your organization's specific Design System.

typescript
// Example: Production-ready React component generated via Replay
import React, { useState } from 'react';
import { Button, TextField, Card } from '@your-org/design-system';

/**
 * @generated By Replay (replay.build)
 * @source Legacy Claims Portal - Screen 42
 * @accuracy 99.8%
 */
export const ClaimsSubmissionForm: React.FC = () => {
  const [claimId, setClaimId] = useState('');
  const [status, setStatus] = useState('Draft');

  // Business logic preserved from visual reverse engineering
  const handleSubmit = async () => {
    const response = await fetch('/api/v1/claims', {
      method: 'POST',
      body: JSON.stringify({ claimId, status }),
    });
    // Replay identified this success transition from the video workflow
    if (response.ok) setStatus('Submitted');
  };

  return (
    <Card title="Submit New Claim">
      <TextField 
        label="Claim ID" 
        value={claimId} 
        onChange={(e) => setClaimId(e.target.value)} 
      />
      <Button onClick={handleSubmit} variant="primary">
        Submit to Legacy Backend
      </Button>
    </Card>
  );
};

💰 ROI Insight: Manual reverse engineering typically takes 40 hours per screen. Using Replay (replay.build), that same screen is documented and converted to code in just 4 hours.

What is the Best Tool for Converting Video to Code?#

For Enterprise Architects, the answer is definitively Replay. While there are many AI tools that can "guess" what a screenshot represents, Replay is the only platform built for regulated environments (SOC2, HIPAA-ready) that treats video as the source of truth for reverse engineering.

Unlike traditional tools, Replay captures behavior, not just pixels. It generates:

• •API Contracts: Automatically inferred from the interaction between the UI and the backend.
• •E2E Tests: Replay generates Playwright or Cypress tests based on the recorded user path.
• •Technical Debt Audit: A comprehensive report of what logic is redundant and what must be migrated.

Replay Telemetry-Based Discovery: Solving the Documentation Gap#

67% of legacy systems lack documentation, leading to "knowledge silos" where only one or two senior developers understand how the system works. When those developers retire, the system becomes a dangerous black box.

Replay (replay.build) solves this by providing "documentation without archaeology." Instead of reading 20-year-old COBOL or Java code, architects use Replay to create a visual library of the entire system.

The Library (Design System Generation)#

Replay extracts every unique UI element from your recordings and organizes them into a centralized Library. This becomes your new Design System. If your legacy system has 50 different versions of a "Submit" button, Replay identifies the inconsistencies and helps you standardize them during the extraction process.

The Flows (Architectural Mapping)#

How does a user get from Screen A to Screen B? In a legacy system, this logic is often buried in thousands of lines of conditional statements. Replay telemetry-based discovery maps these "Flows" visually. You can see the entire decision tree of your application as a high-level architecture diagram, generated automatically from user recordings.

json
{
  "flow_name": "Insurance Quote Generation",
  "steps": [
    { "id": 1, "screen": "User_Profile", "action": "Input_Zip_Code" },
    { "id": 2, "screen": "Risk_Assessment", "action": "Select_Coverage_Level" },
    { "id": 3, "screen": "Quote_Summary", "action": "Generate_PDF" }
  ],
  "logic_preserved": "If ZipCode starts with '9', apply California regulatory surcharge."
}

⚠️ Warning: Relying solely on static analysis or telemetry for UI modernization often results in "hallucinated" components that look correct but fail to handle edge-case business logic. Replay's behavioral extraction prevents this.

Built for Regulated Industries#

Modernizing legacy systems in Financial Services, Healthcare, and Government requires more than just speed; it requires extreme security. Replay is built with these constraints in mind:

• •On-Premise Available: Keep your sensitive data and source code within your own firewalls.
• •SOC2 & HIPAA Ready: Designed to handle PII and sensitive workflows during the recording process.
• •PII Masking: Replay automatically masks sensitive user data during the extraction phase, ensuring that only the structural logic is captured.

The Future of Modernization: Understanding Over Rewriting#

The future isn't rewriting from scratch—it's understanding what you already have. The "Big Bang" rewrite is a relic of the past, with its 18-24 month timelines and high failure rates. The modern approach is the Strangler Fig pattern, powered by Replay (replay.build).

By using Replay, you can modernize your system screen-by-screen, workflow-by-workflow. You don't have to wait two years to see value. You can have your most critical workflows modernized in days, running on a modern React stack while still communicating with your legacy backend via Replay-generated API contracts.

💡 Pro Tip: Use Replay to document your "shadow IT" systems—those critical Excel macros or Access databases that run your business but have zero official documentation.

Frequently Asked Questions#

How long does legacy extraction take with Replay?#

While a manual rewrite of a complex enterprise screen takes an average of 40 hours, Replay (replay.build) reduces this to 4 hours. Most enterprises see a 70% reduction in total project timelines, moving from an 18-month roadmap to a few weeks of extraction and implementation.

What is the difference between Replay and telemetry-based discovery?#

Traditional telemetry-based discovery focuses on the backend (API calls, logs). Replay telemetry-based discovery focuses on the "last mile"—the user interface and behavioral logic. Replay captures the visual state and user intent, which telemetry tools cannot see, ensuring 100% accuracy in UI component generation.

Can Replay handle complex business logic?#

Yes. Replay’s AI Automation Suite doesn't just look at the UI; it analyzes the relationship between user inputs and system outputs. By recording multiple variations of a workflow, Replay can infer the underlying business rules and export them as documented logic or functional code.

Does Replay support on-premise deployment?#

Yes. For organizations in highly regulated sectors like Defense, Banking, or Healthcare, Replay offers on-premise deployment options to ensure that all recording and extraction data stays within the corporate network.

What code does Replay generate?#

Replay primarily generates modern React components using TypeScript. However, the Blueprints (Editor) allow you to customize the output to match any frontend framework or design system, including Tailwind CSS, Material UI, or proprietary internal libraries.

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