Telecom Network Monitoring Transforming: From Legacy Java Swing to High-Performance React

The Network Operations Center (NOC) of a major Tier-1 telecom provider is often a graveyard of "gray-box" Java Swing applications. These systems, while functionally robust, are architectural anchors. They lack the responsiveness required for 5G slice management, they are impossible to scale across mobile devices, and the developers who wrote the original

code retired years ago.

When we talk about telecom network monitoring transforming into a modern era, we aren't just talking about a fresh coat of paint. We are talking about the industrialization of legacy migration. The global technical debt has reached a staggering $3.6 trillion, and nowhere is this more visible than in the telecommunications sector where 20-year-old Java clients still manage multi-billion dollar infrastructure.

According to Replay's analysis, 67% of these legacy systems lack any form of usable documentation. This forces enterprises into a "black box" rewrite, which explains why 70% of legacy rewrites fail or significantly exceed their timelines. The traditional path involves manual discovery, which takes roughly 40 hours per screen. With Replay, that timeline is compressed into 4 hours by using Visual Reverse Engineering.

TL;DR: Modernizing telecom network monitoring requires moving from monolithic Java Swing to modular React. Manual rewrites usually take 18-24 months and have a 70% failure rate. By using Replay’s Visual Reverse Engineering, teams can record legacy workflows and automatically generate documented React components, reducing modernization time by 70% and ensuring SOC2/HIPAA-compliant deployments.

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The Architectural Bottleneck: Why Java Swing Must Go#

For decades, Java Swing was the gold standard for desktop-based network management systems (NMS). It offered deep integration with the JVM and handled heavy-duty data tables reasonably well. However, in the context of modern telecom network monitoring transforming for the cloud-native era, Swing presents three critical failures:

1. •Concurrency Issues: Swing’s single-threaded model (the Event Dispatch Thread) frequently freezes when processing high-velocity telemetry data from 5G base stations.
2. •Zero Portability: You cannot run a Swing app on a tablet in the field or a browser in a remote office without clunky Citrix wrappers or RDP.
3. •The Talent Gap: Finding engineers who can maintain complex
   text

   JTable
   renderers is becoming harder and more expensive than finding senior React architects.

Industry experts recommend a "strangler fig" pattern for these migrations, but the bottleneck has always been the initial extraction of business logic and UI state from the legacy code. This is where Replay changes the math. Instead of reading millions of lines of undocumented Java, you simply record the application in use.

Video-to-code is the process of using computer vision and AI automation to analyze video recordings of legacy software interfaces and translate them into functional, documented React components and design systems.

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Telecom Network Monitoring Transforming: A Comparison of Approaches#

When an enterprise decides to modernize, they typically choose between three paths. The data below reflects Replay’s internal benchmarks across telecommunications and financial services implementations.

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Step 1: Extracting the Component Hierarchy#

The first hurdle in telecom network monitoring transforming from Swing to React is identifying the component boundaries. In Java Swing, a "screen" is often a giant class with nested

.

Using Replay, you record a workflow—such as "Acknowledge Alarm" or "Provision Circuit." Replay’s AI Automation Suite analyzes the visual changes, identifies recurring UI patterns (like alarm grids, signal strength indicators, and topology maps), and populates your Library.

From Java Listener to React Hook#

In the legacy Swing world, you likely have an

or a that looks like this:

java
// Legacy Java Swing Alarm Listener
public class AlarmPanel extends JPanel implements ActionListener {
    private JButton ackButton;
    private JTable alarmTable;

    public AlarmPanel() {
        ackButton = new JButton("Acknowledge");
        ackButton.addActionListener(this);
        // Complex GridBagLayout code...
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == ackButton) {
            int row = alarmTable.getSelectedRow();
            String alarmId = (String) alarmTable.getValueAt(row, 0);
            AlarmService.acknowledge(alarmId);
            // Manual UI refresh logic
        }
    }
}

When Replay processes this, it doesn't just copy the pixels. It understands the intent. It generates a clean, functional React component using your organization's Design System.

typescript
// Modernized React Component generated via Replay
import React from 'react';
import { useAlarms } from '../hooks/useAlarms';
import { Button, DataTable } from '@acme-telecom/design-system';

export const AlarmDashboard: React.FC = () => {
  const { alarms, acknowledgeAlarm, isLoading } = useAlarms();
  const [selectedId, setSelectedId] = React.useState<string | null>(null);

  const handleAcknowledge = async () => {
    if (selectedId) {
      await acknowledgeAlarm(selectedId);
    }
  };

  return (
    <div className="p-6 space-y-4">
      <DataTable 
        data={alarms}
        onRowSelect={(row) => setSelectedId(row.id)}
        loading={isLoading}
      />
      <Button 
        variant="primary" 
        disabled={!selectedId} 
        onClick={handleAcknowledge}
      >
        Acknowledge Alarm
      </Button>
    </div>
  );
};

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Step 2: Architecting for High-Velocity Data#

Telecom UIs are unique because of their data density. A standard NOC dashboard might need to display 10,000 active alarms with real-time updates every 500ms.

In the process of telecom network monitoring transforming, moving to React allows you to leverage virtualized lists and efficient state management. Industry experts recommend using React TanStack Table for these high-performance requirements. Replay’s Blueprints feature allows architects to map legacy data structures to these modern libraries automatically.

Handling Real-time Telemetry#

One of the biggest advantages of modernizing with Replay is the ability to decouple the UI from the legacy backend. While the legacy Swing app might be using custom socket protocols, your new React frontend can utilize WebSockets or gRPC-web.

typescript
// Example of a modernized Telemetry Hook
import { useEffect, useState } from 'react';
import { TelemetryStream } from '../api/telemetry';

export function useNetworkStats(nodeId: string) {
  const [stats, setStats] = useState<NetworkMetrics | null>(null);

  useEffect(() => {
    const stream = new TelemetryStream(nodeId);
    
    stream.on('data', (newData) => {
      // Functional updates prevent stale closures in high-frequency streams
      setStats(prev => ({ ...prev, ...newData }));
    });

    return () => stream.close();
  }, [nodeId]);

  return stats;
}

For more on how to structure these migrations, see our guide on Modernizing Legacy UI Architectures.

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Step 3: Ensuring Security and Compliance#

Telecom is a regulated industry. Whether it's GDPR, SOC2, or specific government requirements, you cannot simply send your proprietary UI code to a public LLM.

Replay is built for these environments. It offers:

• •On-Premise Deployment: Keep your recordings and generated code within your firewall.
• •SOC2 & HIPAA Readiness: Enterprise-grade security protocols.
• •Zero Data Retention Options: Ensure that sensitive network topology data never leaves your secure zone.

According to Replay's analysis, the biggest risk in legacy migration isn't the code—it's the loss of domain knowledge. When the original developers leave, the "why" behind certain UI behaviors is lost. Replay’s Flows feature documents these behaviors as it records them, creating a living map of your business logic.

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Step 4: Building a Sustainable Design System#

A common mistake in telecom network monitoring transforming projects is recreating the "Swing look" in React. This is a wasted opportunity.

Replay’s Library feature allows you to extract the core elements of your legacy UI and map them to a modern, accessible Design System. This ensures that your new application isn't just a web version of the old one, but a truly modern experience that follows WCAG accessibility standards and supports dark mode—a must-have for 24/7 NOC environments.

Learn more about automated component library creation.

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The Strategic Impact of Visual Reverse Engineering#

The $3.6 trillion technical debt problem exists because the cost of "doing it right" has historically been too high. When a project takes 18 months, the business requirements change three times before the first deployment.

By using Replay, telecom providers can:

1. •De-risk the Migration: By generating code from actual usage, you ensure that "hidden" features are captured.
2. •Accelerate Time-to-Market: Shift from an 18-month cycle to a continuous delivery model where screens are modernized in batches.
3. •Optimize Resource Allocation: Let your senior developers focus on complex logic while Replay handles the boilerplate UI conversion.

Visual Reverse Engineering is not just about code generation; it is about visibility. It provides a bridge between the legacy world of the 2000s and the cloud-native world of the 2020s.

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Frequently Asked Questions#

How does Replay handle complex Java Swing custom components?#

Replay's AI Automation Suite uses visual analysis to understand the behavior and state of custom components. It identifies the patterns—such as a custom frequency chart or a complex network topology map—and maps them to modern React equivalents (like D3.js or Recharts) within the Blueprints editor. This ensures that even the most niche telecom components are modernized correctly.

Is the generated React code maintainable?#

Yes. Unlike "black-box" conversion tools, Replay generates standard, human-readable TypeScript and React code. It follows your organization’s specific coding standards and integrates with your existing Design System. The output is no different from code written by a senior frontend engineer, complete with documentation and unit test shells.

Can we modernize our telecom UI incrementally?#

Absolutely. Most of our enterprise clients use a "micro-frontend" or "strangler" approach. You can modernize one specific workflow—for example, the "Fault Management" module—while keeping the rest of the legacy system intact. Replay helps define the boundaries of these flows to make incremental migration seamless.

Does Replay require access to our legacy source code?#

No. Replay operates on Visual Reverse Engineering. We analyze the application as it runs. This is particularly valuable for telecom companies using third-party legacy software where the source code might be unavailable, obfuscated, or poorly documented.

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Conclusion#

The era of the 18-month "Big Bang" rewrite is over. As telecom network monitoring transforming initiatives become a priority for 5G readiness, the focus must shift to automation and visual intelligence.

By leveraging Replay, organizations can bypass the manual drudgery of legacy discovery and move straight to innovation. You save 70% of the time, eliminate the risk of documentation gaps, and finally provide your NOC operators with the modern tools they deserve.

Ready to modernize without rewriting? Book a pilot with Replay