IBM Bob Java Modernization: Migrating Legacy Struts Application into a Modern React & Spring Boot Microservices

In this document, you will find detailed guidance on how to use IBM Bob, an AI-powered software engineering assistant that helps modernize legacy Java applications with speed, accuracy, and confidence.

In this demo, we modernize PKS Auto Insurance, a monolithic Java application built with Struts 1.3, JSP views, and Hibernate 3.5, running on Java 6.

Using a series of simple prompts, Bob transforms this 20-year-old monolithic application into a modern microservices-based platform built with Spring Boot 3.x, PostgreSQL, JWT-based security, and a React 18 frontend. The solution includes generated documentation, automated tests, deployment assets, and operational artifacts.

1. Legacy Application Section

You can see the classic Struts project files here

This is LoginAction.java — a Struts Action class.

Here's the struts-config.xml — all URL mappings, form beans, and action forwards configured in XML.

And here is the service layer , where the business logic is tightly coupled to the application architecture and lacks automated unit test coverage and all.

This is exactly the kind of legacy code that Bob is designed to modernize.

2. Initial Prompt with Bob for Migration

Now let's see Bob in action. We simply describe what we want in the prompt.

Download this repo to local folder.
Delete the modernized folder.
Open the folder in IBM bob,
Provide the following prompt to IBM Bob :

I have a legacy Java application that I want to modernize into a ReactJS frontend, Spring Boot and Tomcat-based microservices, PostgreSQL database, and deploy on OpenShift.
I need Bob to perform the following tasks:

Analyze the existing application code.
Create an HTML document describing the current application, including its architecture, technology stack, application inventory, dependencies, and other relevant details.
Prepare SRE documentation in HTML format.
Identify and recommend microservices based on Domain-Driven Design (DDD) principles and document them in HTML format.
Create a Bounded Context Map and provide it in HTML format.
Convert the monolithic application into microservices.
Create a traceability matrix between the legacy application and the modernized solution in HTML format.
Create database migration documentation in HTML format.
Perform the database migration to PostgreSQL.
Generate unit test scripts.
Create unit test case documentation in HTML format.
Create integration test case documentation in HTML format.
Generate integration test scripts.
Create a DevSecOps pipeline plan and documentation in HTML format.
Generate Jenkins pipeline scripts for the DevSecOps implementation.
Create Jenkins installation and configuration scripts for OpenShift.
Create deployment scripts and manifests for deploying the microservices on OpenShift.
Additionally, I want to run and test the application on my local Mac. Please provide the required steps, setup instruction, scripts and etc in HTML format.

Please start by analyzing the application and then generate the deliverables one by one in the order listed above.

Bob immediately begins reverse-engineering the legacy codebase by extracting business rules, mapping domain models, and identifying bounded contexts. It then forward-engineers a complete modernized platform based on its analysis.

Within moments, three independent Spring Boot microservices appear: user-service, vehicle-service, and premium-service — each with its own schema, security configuration, REST API, and test suite.

The React frontend, Docker Compose file, Jenkins pipeline, OpenShift manifests, and HTML documentation files are all generated in parallel.

Navigate to the generated modernized folder (or its equivalent output directory) to review the generated source code, documentation, configuration files, and deployment assets.

3. Additional Prompts with Bob for improvements.

What makes Bob truly powerful is that the conversation continues. As we test the application, we encounter real-world issues — and we fix them with plain English prompts.

Flyway

You can give the prompt to remove the Flyway dependency.

Bob removes the Flyway dependency from all three Maven projects, eliminates Flyway-related configuration from the application configuration files, and generates standalone SQL scripts suitable for manual database initialization.

CORS

CORS Configuration

The frontend was experiencing cross-origin request failures due to missing CORS configuration.

Provide a prompt asking Bob to resolve the CORS issue.

Bob identified the root cause and updated the services accordingly.

In the user-service, Bob added a CorsConfigurationSource bean within the SecurityConfig class.

For the vehicle-service and premium-service, Bob configured the required CORS mappings to allow frontend access.

These changes enable secure and reliable communication between the React frontend and the backend microservices.

React SPA

You can give the prompt to fix the SPA issue.

With a simple prompt, Bob transforms the user interface into a modern React single-page application (SPA), providing a seamless and responsive user experience.

Modernization process documents

Provide a prompt requesting modernization documentation.

With a single prompt, Bob generates a collection of comprehensive, client-ready HTML documents covering every aspect of the modernization process—from reverse-engineering activities and domain discovery to migration validation and confidence scoring.

These documents are ready to share with stakeholders immediately.

Migrated Application

Here is the converted and migrated application.

4. HTML documentation files

Let's take a moment to walk through everything Bob has produced.

Fifteen HTML documentation files — a complete modernization knowledge base.