Technical debt in IBM application modernization poses a significant challenge for businesses. It slows innovation and makes it harder for organizations to implement new ideas effectively. While most IT executives recognize modernization as a strategic priority, many still struggle to fully update their core workflows—highlighting a gap between intent and execution.
Organizations now prioritize reducing technical debt without complete rewrites. This becomes especially crucial during IBM i modernization and broader iSeries modernization initiatives. Legacy applications often lack modularity, proper documentation, and integration capabilities. IBM i application modernization companies must reduce this debt while business operations continue smoothly. Similarly, mainframe applications carry technical debt that organizations must manage to meet their business goals.
In this piece, we'll show you how IBM application modernization services can reduce technical debt without starting from scratch. You'll learn about core technical challenges, proven modernization patterns, and tool-based approaches that optimize the process and improve sustainability over time.
Core Technical Debt Challenges in IBM i Applications
IBM i legacy systems face several technical debt challenges that make modernization difficult. Teams need to understand these challenges before they can create working solutions.
Tightly Coupled Business Logic and UI Layers
Legacy IBM i applications use monolithic design patterns. Business logic, database access, and user interface are tightly integrated within a single program object. The historically high computational costs for activating programs led developers to include all logic in one program. Programs with thousands of lines of code became common, where presentation and data access layers were merged into one executable.
Unlike modern languages that need separate libraries or APIs to access databases, RPG differs by offering native access to both the database and the user interface. This design choice created better performance but came at the cost of architectural flexibility. Developers who needed to reuse logic duplicated it into other programs. Changes to business rules needed updates in multiple programs, which made maintenance more complex.
Hardcoded Parameters and Static Configurations
Hardcoded parameters create major technical debt in IBM i applications. Developers often use hard-coding during quick fixes, onboarding new trading partners, or policy changes. This debt grows faster as teams clone code and lose documentation.
Static configurations further compound the challenge:
- Applications need rebuilding, retesting, and redeploying after configuration changes
- Customizing packaged software voids the "warranty seal" and removes vendor support
- Traditional AS/400 programs rely on positional parameters, which makes maintenance hard
Dynamic configurations offer a solution that lets applications adapt without rebuilding.
Lack of Automation and Testing Infrastructure
Many IBM i environments still rely on manual processes. This makes them prone to human error and inefficiencies. Organizations using IBM i can reduce redundant manual data entry and minimize errors through process automation.
Testing presents its own set of challenges. IBM i system's terminal-based UI doesn't work well with traditional test automation frameworks. ID-based automation can't handle AS/400's unpredictable elements and session IDs. Batch programs, which often run mission-critical applications, create complex database and IBM i spool file defects. This results in prolonged debug cycles.
Companies must address these technical debt challenges systematically. IBM i modernization strategies should preserve business logic while making systems more modular and maintainable.
Modernization Patterns Without Rewriting from Scratch
Organizations need specific patterns and tools to modernize IBM i applications without full-scale rewrites. These tools help balance legacy preservation with technological advancement. Companies can adopt proven approaches that gradually reduce technical debt, avoiding costly overhauls.
Runtime Modernization with WebSphere Liberty
WebSphere Liberty provides a strategic path to modernize IBM i applications with minimal disruption. Liberty helps organizations migrate applications without the effort of rewriting them. This lightweight runtime works perfectly for cloud-native applications and microservices, enabling startup times under two seconds.
The migration process usually includes:
- Runtime definition through Dockerfile and pom.xml modifications
- Liberty server.xml configuration with required Liberty features
- Targeted code changes based on the WebSphere Application Server Migration Toolkit
Most applications need only minor code adjustments, like updating EJB lookups and replacing proprietary APIs with open-source alternatives. This approach works best, especially when organizations are seeking to maintain business continuity while migrating to containerized environments.
Replatforming with IBM Cloud Pak for Applications
IBM Cloud Pak for Applications delivers a detailed solution for modernizing existing IBM i applications. The platform combines WebSphere offerings with Red Hat OpenShift Container Platform to bridge traditional applications and cloud environments.
Replatforming allows organizations to run VMs and containers side by side on a single platform. Businesses can smoothly transition from on-premises to hybrid cloud deployments without disrupting their core operations.
Refactoring with IBM Mono2Micro and Transformation Advisor
IBM Mono2Micro uses AI-powered modernization that automatically creates microservice recommendations from monolithic Java applications. The system analyzes runtime traces aligned with real business use cases and applies machine learning algorithms to identify business logic boundaries and class dependencies.
Transformation Advisor complements this process by examining on-premises workloads to determine application complexity and identify potential migration issues. The tool calculates development costs for cloud migration and produces deployment artifacts that speed up execution. Simple applications can implement the migration plan without code changes, while moderate or complex ones might need targeted modifications.
These patterns help an IBM i modernization company reduce technical debt while preserving existing business logic. They are the foundations of balancing state-of-the-art technology with preservation.
Tool-Based Approaches to Reduce Technical Debt
Several specialized tools make IBM i and iSeries modernization easier while keeping technical debt low. These tools provide systematic ways to analyze, refactor, test, and document applications.
Using IBM Cloud Transformation Advisor for Discovery
IBM Cloud Transformation Advisor helps assess on-premises workloads faster for modern deployment options. Using a custom discovery tool, it scans application servers and uploads results for in-depth analysis. The tool creates a high-level inventory of application content and structure, determines complexity, and spots shared library dependencies. The Transformation Advisor goes beyond assessment to help with strategic planning. It identifies applications that need upgrades and estimates migration effort. The tool creates migration bundles that help with containerization by creating files custom-made for specific applications.
Modularization with IBM Mono2Micro
IBM Mono2Micro uses AI-based algorithms to transform Java monolithic applications into microservices. This semi-automated tool analyzes applications both statically and dynamically. It then recommends class partitions that can be converted into microservices. Developers can explore these suggestions through a graph view that shows class relationships and dependencies, enabling informed decisions before generating code for Liberty deployment.
Automated Testing with RPGUnit and DevOps Pipelines
IBMiUnit is inspired by popular JUnit and xUnit frameworks and lets RPG developers build repeatable test cases for programs, subprocedures, and methods. The framework has various built-in unit tests, including indicator, pointer, and variable tests. DevOps pipelines provide the quickest way to manage applications throughout development lifecycles. These pipelines automatically create deployment plans, take input from source control repositories, and run jobs one after another for consistent flow control.
Documentation Generation with ARCAD Observer
ARCAD Observer analyzes IBM i applications and databases to create a comprehensive knowledge base. Software development teams usually spend half their time understanding an application's architecture before implementing changes. ARCAD Observer speeds up this process by visually mapping architecture, business logic, and dependencies—down to the source line and field level. The tool's key features include I/O diagrams, database relationship models, calling chain diagrams, flowcharting, and source code analysis. It also creates technical documentation that helps readers understand without reading source code.
Conclusion
Technical debt remains a big obstacle for businesses that use IBM i systems. While companies today understand the need for modernization, they often struggle to achieve it without disrupting critical operations.
Legacy systems need a balanced approach. Companies must align their immediate business needs with long-term sustainability goals. Fortunately, several proven modernization patterns eliminate the need for costly rewrites. WebSphere Liberty, IBM Cloud Pak for Applications, and AI-powered tools like Mono2Micro provide practical paths to modernization and preserve valuable business logic.
Tool-based approaches simplify modernization efforts. The Transformation Advisor streamlines discovery and assessment phases. Automated testing frameworks ensure reliability during the transition. These tools lay the groundwork for sustainable application management.
IBM i application modernization doesn't mean starting over. Companies can take small steps that gradually reduce technical debt while keeping operations running smoothly. This balanced approach lets businesses evolve at their own pace. They ultimately create more sustainable, maintainable, and eco-friendly systems for tomorrow.