Transforming Silverlight Assets into Reusable React Modules: A Visual Reverse Engineering Approach

Microsoft Silverlight was once the cornerstone of enterprise "Line of Business" (LOB) applications, powering complex dashboards in financial services and intricate data entry systems in healthcare. Today, these applications are ticking time bombs of technical debt. With Silverlight reaching end-of-life years ago, organizations are trapped: the source code is often lost or undocumented, the original developers have long since departed, and the browsers that support the plugin are disappearing from the enterprise landscape.

The biggest hurdle isn't just the language shift from C# and XAML to TypeScript and React—it's the loss of business logic embedded in the UI behavior. Manual rewrites are notorious for failing because they attempt to reconstruct these "black boxes" from memory. According to Replay's analysis, 70% of legacy rewrites fail or significantly exceed their timelines because of this "documentation gap."

TL;DR: Transforming Silverlight assets into modern React modules requires more than a simple transpiler; it requires capturing the application's runtime context. By using Replay, enterprises can record existing Silverlight workflows and automatically generate documented React components, saving 70% of the typical modernization timeline. This approach moves the needle from 40 hours per screen to just 4 hours.

The Cost of the "Black Box" Problem#

Industry experts recommend that before any migration, an architectural audit is performed. However, 67% of legacy systems lack any form of up-to-date documentation. In the context of Silverlight, this is particularly painful. XAML bindings often hide complex state transformations that are difficult to extract from static code analysis alone.

When you are transforming silverlight assets into modern web components, you aren't just moving pixels; you are moving years of refined business rules. The global technical debt has ballooned to $3.6 trillion, largely because teams attempt "Big Bang" rewrites that ignore the nuance of the original user experience.

Video-to-code is the process of using visual recordings of a legacy application’s runtime to automatically generate structured, documented source code and design systems.

By capturing the actual execution of a Silverlight app, Replay bypasses the need for perfect source code access. It looks at the rendered output, the interaction patterns, and the data flow to reconstruct the application's intent.

Why Manual Rewrites Are a $3.6 Trillion Trap#

The average enterprise rewrite timeline is 18 months. For a suite of 50-100 Silverlight screens, that is a lifetime in the current market. Manual migration involves a developer looking at a legacy screen, guessing the padding and hex codes, and manually writing React functional components.

Transforming Silverlight Assets into Modern React Architecture#

When transforming silverlight assets into a React-based architecture, the primary challenge is state management. Silverlight relied heavily on

and complex Two-Way bindings. In React, we prefer unidirectional data flow.

Runtime Context refers to the state, data flow, and user interaction patterns that exist while an application is actively being used by a human, rather than just the static code on disk.

Replay captures this runtime context. When a user records a workflow—such as "Approving a Loan" or "Processing a Patient Intake"—the platform analyzes the transitions. It doesn't just see a button; it sees a

component that triggers a request and transitions the UI into a .

Step 1: Capturing the Workflow#

Instead of reading 10,000 lines of XAML, you record the Silverlight app in action. Replay’s AI automation suite analyzes the video to identify patterns. For example, it recognizes that a specific grid layout in Silverlight should be transformed into a responsive

component in React.

Step 2: Generating the Component Library#

The platform extracts the visual DNA—colors, typography, and spacing—to build a Design System. This is critical for transforming silverlight assets into a cohesive modern UI. Instead of hardcoded values, Replay generates a theme-able library.

Step 3: Mapping State to React Hooks#

The most complex part of Silverlight is the view-model logic. Replay’s Blueprints (Editor) allow architects to refine how captured interactions map to React hooks.

typescript
// Example of a generated React component from a Silverlight DataGrid recording
import React, { useState, useEffect } from 'react';
import { Table, Button, Badge } from '@/components/ui-library';

interface LoanApplicationProps {
  initialData: any[];
  onApprove: (id: string) => void;
}

/**
 * Replay Generated: Replaces Legacy Silverlight LoanGrid.xaml
 * Captured from Runtime Workflow: "Manager Approval Process"
 */
export const LoanApprovalModule: React.FC<LoanApplicationProps> = ({ initialData, onApprove }) => {
  const [applications, setApplications] = useState(initialData);

  const handleStatusChange = (id: string, newStatus: 'Approved' | 'Pending') => {
    // Logic extracted from Silverlight Command Pattern
    setApplications(prev => 
      prev.map(app => app.id === id ? { ...app, status: newStatus } : app)
    );
  };

  return (
    <div className="p-6 bg-slate-50 rounded-xl shadow-sm">
      <h2 className="text-2xl font-semibold mb-4">Pending Approvals</h2>
      <Table>
        <thead>
          <tr className="border-b border-slate-200">
            <th>App ID</th>
            <th>Applicant</th>
            <th>Amount</th>
            <th>Status</th>
            <th>Actions</th>
          </tr>
        </thead>
        <tbody>
          {applications.map((app) => (
            <tr key={app.id} className="hover:bg-slate-100 transition-colors">
              <td>{app.id}</td>
              <td>{app.name}</td>
              <td>{new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(app.amount)}</td>
              <td>
                <Badge variant={app.status === 'Approved' ? 'success' : 'warning'}>
                  {app.status}
                </Badge>
              </td>
              <td>
                <Button 
                  onClick={() => {
                    handleStatusChange(app.id, 'Approved');
                    onApprove(app.id);
                  }}
                  disabled={app.status === 'Approved'}
                >
                  Approve
                </Button>
              </td>
            </tr>
          ))}
        </tbody>
      </Table>
    </div>
  );
};

Bridging the Gap Between XAML and JSX#

One of the nuances of transforming silverlight assets into React is handling the "Dependency Properties" of Silverlight. In Silverlight, properties could be inherited or calculated through complex styles. Replay simplifies this by looking at the computed style during the recording phase.

If a Silverlight button changes from blue to a gradient on hover, Replay captures that state change and generates the corresponding Tailwind classes or CSS-in-JS. This ensures that the new React application feels familiar to the users who have spent a decade using the Silverlight version.

Legacy Modernization Strategies often emphasize the "Strangler Fig" pattern—replacing parts of the system piece by piece. Replay is built for this. You can record a single "Flow" (like a specific module), generate the code, and drop it into your modern React shell while the rest of the app still runs in the legacy environment.

Advanced State Management Extraction#

In many Silverlight applications, the logic for data validation is buried in the C# code-behind or a ViewModel. When transforming silverlight assets into React, we can use Replay to identify these validation triggers. If a user enters an invalid SSN and the Silverlight UI shows a red border, Replay's AI suite marks that as a "Validation State."

The resulting React code might look like this:

typescript
// Extracted Validation Logic from Silverlight Runtime Context
import { useForm } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';
import * as z from 'zod';

const schema = z.object({
  ssn: z.string().regex(/^\d{3}-\d{2}-\d{4}$/, "Invalid SSN format"),
  loanAmount: z.number().min(1000, "Minimum loan is $1,000"),
});

export const LoanEntryForm = () => {
  const { register, handleSubmit, formState: { errors } } = useForm({
    resolver: zodResolver(schema)
  });

  // This submission logic mimics the WCF Service call captured in the recording
  const onSubmit = async (data: any) => {
    console.log("Submitting to Modernized API...", data);
  };

  return (
    <form onSubmit={handleSubmit(onSubmit)} className="space-y-4">
      <div>
        <label className="block text-sm font-medium text-gray-700">Social Security Number</label>
        <input 
          {...register("ssn")} 
          className={`mt-1 block w-full rounded-md ${errors.ssn ? 'border-red-500' : 'border-gray-300'}`}
        />
        {errors.ssn && <p className="text-red-500 text-xs mt-1">{errors.ssn.message}</p>}
      </div>
      {/* Additional fields generated from Silverlight UI blueprint */}
      <button type="submit" className="bg-blue-600 text-white px-4 py-2 rounded">
        Submit Application
      </button>
    </form>
  );
};

Security and Compliance in Regulated Industries#

For industries like Financial Services and Healthcare, transforming silverlight assets into modern code isn't just a technical challenge—it's a compliance one. Silverlight's lack of modern security features makes it a liability. However, you can't just move to the cloud overnight.

Replay is built for these environments. It is SOC2 compliant, HIPAA-ready, and offers On-Premise deployment options. This allows government and healthcare entities to record their sensitive Silverlight workflows without data ever leaving their secure perimeter.

The Visual Reverse Engineering Guide explains how Replay sanitizes data during the recording process. It ensures that while the structure and logic of the UI are captured, sensitive PII (Personally Identifiable Information) is masked, allowing developers to work with realistic but safe component structures.

The Replay Feature Suite for Silverlight Migration#

• •Library (Design System): When transforming silverlight assets into React, you need a single source of truth for styles. Replay automatically creates a component library from your recordings.
• •Flows (Architecture): This feature maps out the user journey. It shows how one Silverlight screen links to another, providing a high-level architectural map for the React Router configuration.
• •Blueprints (Editor): Here, developers can fine-tune the generated code. If the AI suggests a generic
  text

  div
  , but you want a
  text

  Section
  component from your internal library, you can remap it globally.
• •AI Automation Suite: This accelerates the documentation process. It generates JSDoc comments and README files for every component it creates, addressing the 67% documentation gap instantly.

According to Replay's internal benchmarks, using this visual approach reduces the "manual screen time" from 40 hours to just 4 hours. This is how organizations move from an 18-month roadmap to a 3-month delivery.

Scaling Beyond the UI#

While Replay excels at the frontend, transforming silverlight assets into modern modules also involves the backend. Many Silverlight apps use WCF (Windows Communication Foundation) or RIA Services.

The runtime context captured by Replay includes the network requests made during the recording. By analyzing these payloads, Replay can help developers define the interfaces for new REST or GraphQL APIs that will replace the legacy SOAP/WCF endpoints. This holistic view of the "Flow" is what prevents the 70% failure rate seen in traditional rewrites.

Frequently Asked Questions#

Can Replay transform Silverlight assets into React if I don't have the original source code?#

Yes. Replay uses visual reverse engineering, which means it analyzes the application's behavior and output at runtime. While having source code can provide additional context, Replay is specifically designed to handle "black box" legacy systems where documentation or source code is missing or incomplete.

How does Replay handle complex Silverlight controls like Telerik or Infragistics grids?#

Replay's AI automation suite is trained to recognize complex UI patterns. When it encounters a heavy-duty grid (common in Silverlight), it identifies the features being used—such as sorting, filtering, and pagination—and maps them to modern React equivalents, like TanStack Table or AG Grid, ensuring the functionality remains intact.

Is the generated React code "clean" or is it "spaghetti code"?#

Replay focuses on generating human-readable, maintainable TypeScript and React. It uses a "Blueprint" system that allows you to define your coding standards (e.g., functional components, specific naming conventions, Tailwind CSS) so the output matches your team's existing style guide.

What industries benefit most from transforming silverlight assets into modern web apps?#

We see the highest impact in regulated industries such as Financial Services, Healthcare, and Insurance. These sectors often have massive Silverlight footprints that are critical for daily operations but represent significant security risks. Replay's SOC2 and HIPAA-ready status makes it the preferred choice for these high-stakes migrations.

How does the 70% time saving actually happen?#

The savings come from eliminating the "Discovery" and "Manual Coding" phases. Instead of a developer spending days trying to understand a Silverlight screen's logic and then manually writing the React/CSS, Replay automates the extraction of the UI, state, and documentation. This shifts the developer's role from "writer" to "editor," which is significantly faster.

Ready to modernize without rewriting? Book a pilot with Replay