Organizations are under constant pressure to improve IT infrastructure to stay competitive. A critical aspect of this improvement lies in legacy code modernization, especially for systems built on AS400 (IBM i) that continue to run essential workloads in sectors like finance, manufacturing, and healthcare.

These legacy systems, written primarily in RPG or COBOL, form the core of many enterprise operations but can become performance bottlenecks over time. In this blog, we’ll walk through automation-driven approaches to code modernization, offering tools, strategies, and techniques that can help you modernize without disruption.

What is Legacy Code Modernization?

It refers to upgrading outdated or obsolete software code to make it more maintainable, efficient, and compatible with current technologies. In the context of AS400 systems, this usually means refactoring RPG and COBOL code to work within modern architectures using updated programming languages like Java or C#.

Benefits

  • Performance Gains: Optimize old code to run on modern hardware.
  • Maintainability: Easier for current developers to understand and enhance.
  • Integration: Connect seamlessly with APIs, cloud platforms, and newer software systems.
  • Security: Reduce vulnerabilities by moving away from unsupported technologies.
  • Compliance: Meet regulatory requirements by upgrading unsupported platforms.

Why Is It Essential Today?

Complexity of Legacy Systems

Legacy systems have often evolved over decades, with multiple patches and undocumented workarounds. This results in complex and fragile codebases that resist change.

Business Risk

A failure in these aging systems can result in high costs, lost revenue, and compromised customer experience. Any delay in modernization is a delay in risk mitigation.

Lack of Skilled Developers

Fewer developers are proficient in legacy languages like RPG and COBOL. As this workforce retires, the talent gap widens, putting long-term sustainability at risk.

Also read: Top 10 areas for IBMi Modernization

Key Strategies with Automation

Automated Code Analysis

Tools like X-Analysis by Fresche Solutions help dissect and understand the structure and dependencies in RPG/COBOL codebases, allowing your teams to:

  • Uncover hidden dependencies.
  • Identify reusable components.
  • Pinpoint dead or redundant code.
  • Code Visualization: Visual maps make it easier to understand call hierarchies and relationships between modules.

Automated Refactoring Tools

ARCAD Transformer RPG
Converts RPG logic to Java automatically, preserving business logic while reducing manual effort.

Micro Focus Enterprise Analyzer
Supports COBOL modernization by analyzing the existing code and suggesting automated transformations to Java or C#.

Modernization Frameworks for IBM i

LANSA

Provides a complete modernization framework, including code transformation, front-end enhancements, and integration enablers.

Profound Logic

Offers GUI modernization, REST API enablement, and code transformation services for a phased and low-risk modernization process.

Tools for Effective Modernization

Code Analysis & Discovery Tools

X-Analysis: Dependency mapping, dead code detection, and architecture insights.

IBM Rational: Integrated code management and analysis for RPG and COBOL systems.

Refactoring & Conversion Tools

ARCAD Transformer RPG: Automates RPG to Java conversion with minimal business disruption.

Micro Focus Analyzer: Assists in COBOL transformation and post-conversion validation.

Integrated Development Environments (IDEs)

RDi (Rational Developer for i): IBM’s IDE for RPG and COBOL with modern tooling.

Eclipse with WDSC Plugins: Offers flexibility for cross-platform development and modernization.

Let us help you use these tools to perfection!

Speak to an expert

Best Practices in Projects

Take an Incremental Approach

Don’t go for a full rewrite all at once. Start small with high-impact modules. Validate frequently to minimize disruption.

Use Automated Testing

Testing is crucial after every code transformation.

  • JUnit for Java
  • NUnit for C#/.NET

These tools allow you to catch regressions and confirm functionality.

Embrace CI/CD Pipelines

Automate builds, testing, and deployment for faster feedback and continuous integration.

  • Jenkins: Flexible, plugin-rich CI/CD server.
  • GitLab CI: Great for teams using GitLab repositories.
  • Azure DevOps: Full CI/CD pipeline for cross-platform teams.

Legacy Code Modernization on AS400 – A Closer Look

If your enterprise relies on AS400 systems, modernization isn’t a "good-to-have", but a necessity. These platforms support mission-critical workflows, and delaying their upgrade can result in:

  • Compatibility issues with modern applications.
  • Difficulty integrating with cloud-based solutions.
  • Rising maintenance costs due to niche skill requirements.

Automating the process helps reduce these barriers, enabling quicker time to value while preserving business logic and ensuring operational continuity.

Also read: Why are CI/CD and DevOps NOT Interchangeable?

Final Thoughts

Legacy code modernization is a strategic initiative to future-proof your enterprise. From automated code analysis and transformation tools to testing frameworks and CI/CD pipelines, automation allows you to modernize confidently and cost-effectively.

Whether you’re migrating from RPG to Java, COBOL to C#, or simply refactoring for better maintainability, leveraging the right tools and best practices ensures a smoother journey.

Need help transforming your legacy code?

Let Nalashaa’s experts guide you. Reach out at info@nalashaa.com to start your modernization journey today.