Struts Modernization: Moving 15-Year-Old Java Web Logic to Modern Components

Your Struts 1.x application is a ticking time bomb. Released in 2001 and reaching End-of-Life (EOL) in 2013, Struts 1.x still powers a staggering number of core banking systems, insurance underwriting platforms, and government portals. The developers who wrote the original

logic have long since retired, leaving behind a $3.6 trillion global technical debt mountain.

When we talk about struts modernization moving 15yearold codebases, we aren't just talking about a UI facelift. We are talking about decoupling monolithic Java logic from nested JSP tags and migrating it into a scalable, component-based architecture. Manual rewrites of these systems fail 70% of the time because the business logic is buried in the view layer—making it nearly impossible to document without a massive time investment.

Replay changes this dynamic by using Visual Reverse Engineering to convert recorded user sessions into documented React components, bypassing the need for manual JSP-to-JSX translation.

TL;DR: Struts 1.x modernization is traditionally slow (18-24 months) due to undocumented JSP logic. By using Replay, enterprises can reduce modernization time by 70%, moving from manual screen-by-screen rewrites (40 hours/screen) to AI-automated component generation (4 hours/screen). This guide covers mapping ActionForms to React hooks, handling legacy taglibs, and implementing a "Video-to-Code" workflow.

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The Architecture of Struts Modernization: Moving 15-Year-Old Logic to React#

The primary challenge in any struts modernization moving 15yearold system is the tight coupling between the

, the class, and the JSP. In Struts 1.x, the state of your application is essentially trapped in the and managed via XML configurations ().

According to Replay's analysis, 67% of these legacy systems lack any form of up-to-date documentation. This forces architects into "archeological coding," where they must click through every possible permutation of a screen to understand the underlying business rules.

Why Struts 1.x is a Modernization Nightmare#

1. •Taglib Hell: Custom JSP tags (
   text

   <html:form>
   ,
   text

   <bean:write>
   ) create complex rendering logic that doesn't map 1:1 to HTML.
2. •Server-Side State: Validations happen in the
   text

   ActionForm.validate()
   method, requiring a full round-trip to the server just to check if a field is empty.
3. •The XML Maze: Navigation logic is hidden in thousands of lines of
   text

   struts-config.xml
   , making it impossible to visualize the application flow without running it.

Video-to-code is the process of recording these legacy application workflows in real-time and using AI to identify UI patterns, state transitions, and business logic to generate functional React equivalents.

Comparison: Manual Rewrite vs. Replay Visual Reverse Engineering#

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A Step-By-Step Guide to Struts Modernization: Moving 15-Year-Old Legacy Apps#

To successfully execute a struts modernization moving 15yearold project, you must move from a "Code-First" approach to a "Behavior-First" approach. Industry experts recommend capturing the "as-is" state of the application before touching a single line of Java.

Step 1: Visual Capture and Flow Mapping#

Instead of reading through

, use Replay to record the core workflows of your application. This creates a "Flow," which is a visual representation of the user's journey through the Struts actions.

Component Discovery is the phase where Replay identifies recurring UI patterns—like that 15-year-old data grid or the complex multi-tab insurance form—and adds them to your Design System Library.

Step 2: Mapping ActionForms to React Hooks#

In Struts, the

is a JavaBean that captures input. In a modern React architecture, we replace this with hooks or state management libraries like Redux or Zustand.

Legacy Struts ActionForm (Java):

java
public class UserRegistrationForm extends ActionForm {
    private String username;
    private String email;

    public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) {
        ActionErrors errors = new ActionErrors();
        if (username == null || username.length() < 1) {
            errors.add("username", new ActionMessage("error.username.required"));
        }
        return errors;
    }
    // Getters and Setters...
}

Modern React Equivalent (TypeScript) generated by Replay:

typescript
import React from 'react';
import { useForm } from 'react-hook-form';
import { TextField, Button, Box } from '@mui/material';

interface RegistrationValues {
  username: string;
  email: string;
}

export const RegistrationComponent: React.FC = () => {
  const { register, handleSubmit, formState: { errors } } = useForm<RegistrationValues>();

  const onSubmit = (data: RegistrationValues) => {
    // This maps to the legacy Action class logic
    console.log("Modernized Struts Logic:", data);
  };

  return (
    <Box component="form" onSubmit={handleSubmit(onSubmit)}>
      <TextField
        {...register("username", { required: "Username is required" })}
        label="Username"
        error={!!errors.username}
        helperText={errors.username?.message}
      />
      <Button type="submit">Register</Button>
    </Box>
  );
};

Step 3: Extracting Logic from JSP Taglibs#

The most tedious part of struts modernization moving 15yearold systems is dealing with logic embedded in JSPs. Logic tags like

or must be converted into standard JavaScript map functions or conditional rendering.

Visual Reverse Engineering allows you to see the output of these tags in the browser and immediately generate the corresponding React component. You don't need to know how the

works; you only need to see the result it produces on the screen.

Learn more about Legacy Modernization Strategies

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Technical Deep Dive: Handling the Struts Controller#

One of the biggest hurdles in struts modernization moving 15yearold systems is the

class. These classes often contain thousands of lines of "spaghetti code" involving database calls, session manipulation, and navigation logic.

When using Replay, the focus shifts from the backend Java to the frontend contract. Replay's AI Automation Suite identifies the data structures being sent to the UI. By observing the network traffic and the UI changes simultaneously, Replay can generate a "Blueprint"—an editable template of the modern component that includes the necessary API hooks to replace the legacy

calls.

Example: Modernizing a Legacy Data Grid#

A typical Struts 1.x grid uses

or nested tags. This creates a static HTML table that is difficult to make responsive or interactive.

Modernized React Grid (TypeScript):

typescript
import { DataGrid, GridColDef } from '@mui/x-data-grid';

const columns: GridColDef[] = [
  { field: 'id', headerName: 'ID', width: 90 },
  { field: 'accountName', headerName: 'Account Name', width: 200 },
  { field: 'balance', headerName: 'Balance', type: 'number', width: 150 },
];

// Replay extracts the data shape from your recorded session
export const AccountOverview = ({ data }) => {
  return (
    <div style={{ height: 400, width: '100%' }}>
      <DataGrid
        rows={data}
        columns={columns}
        pageSize={5}
        rowsPerPageOptions={[5]}
        checkboxSelection
        disableSelectionOnClick
      />
    </div>
  );
};

This approach allows you to maintain the exact business functionality of the 15-year-old system while upgrading the underlying technology to a SOC2 and HIPAA-ready modern stack.

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Why 70% of Struts Modernization Projects Fail#

Industry experts recommend looking at modernization as a "re-platforming" exercise rather than a "rewrite." The failure of struts modernization moving 15yearold code often stems from:

1. •Scope Creep: Trying to add new features while migrating legacy ones.
2. •Lack of Domain Knowledge: The original requirements are lost, and the code is the only "source of truth."
3. •Manual Mapping Errors: Developers misinterpret how a complex Struts validator works, leading to data integrity issues in the new system.

Replay mitigates these risks by providing a "Visual Source of Truth." When you record a workflow, you are documenting exactly how the system behaves. This documentation is then used to generate the code, ensuring that the new React components match the legacy behavior 1:1.

What is Visual Reverse Engineering?

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Implementing the Modernization Pipeline#

To move a 15-year-old Struts app to a modern React environment, follow this pipeline:

1. The Audit (Week 1)#

Use Replay to record every screen and user flow. This identifies the total surface area of the application. According to Replay's data, the average enterprise Struts application has between 150 and 400 unique screens.

2. The Library Build (Weeks 2-3)#

Extract global components (headers, footers, buttons, inputs) into a centralized Design System Library. This ensures consistency across the new application.

3. The Blueprint Phase (Weeks 4-8)#

Generate React components for each flow. Use Replay's AI to suggest state management patterns and API integrations. This is where the bulk of the struts modernization moving 15yearold logic is converted.

4. Integration and Testing (Weeks 9+)#

Connect the new React frontend to your modernized backend (Spring Boot, Node.js, etc.). Because the UI is already documented and verified against the original recording, testing time is reduced by 50%.

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Frequently Asked Questions#

Can Replay handle custom Struts taglibs?#

Yes. Replay's Visual Reverse Engineering doesn't parse the Java code; it parses the rendered DOM and the user interactions. This means it can accurately recreate the behavior and appearance of any custom taglib, no matter how complex or old the underlying Java logic is.

How does Replay ensure security in regulated industries?#

Replay is built for regulated environments like Financial Services, Healthcare, and Government. It is SOC2 compliant and HIPAA-ready. For highly sensitive data, Replay offers an On-Premise deployment model, ensuring that your legacy code and recordings never leave your secure infrastructure.

Do we need the original source code to use Replay?#

While having the source code is helpful for backend migration, Replay only requires a running instance of the application to generate the frontend components and documentation. This makes it ideal for struts modernization moving 15yearold systems where the source code might be incomplete or difficult to build.

What is the average time savings compared to a manual rewrite?#

On average, Replay users see a 70% reduction in modernization timelines. A project that would traditionally take 18 months can often be completed in 5-6 months. This is primarily due to the elimination of manual documentation and the automated generation of React components from visual recordings.

Can we modernize incrementally?#

Absolutely. Most organizations choose a "Strangler Fig" pattern, where they modernize one workflow at a time. Replay supports this by allowing you to generate standalone component libraries and flows that can be integrated into your existing infrastructure piece by piece.

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The Future of Legacy Systems#

The "rip and replace" era is over. It’s too expensive, too risky, and takes too long. As we look at the challenges of struts modernization moving 15yearold logic, the path forward is clear: automate the discovery, automate the documentation, and automate the component generation.

By leveraging Visual Reverse Engineering, you aren't just moving away from Struts 1.x; you are building a foundation for the next 15 years of your enterprise architecture. You are turning technical debt into a streamlined, documented, and modern asset.

Ready to modernize without rewriting? Book a pilot with Replay