RPG to Java Migration Services
Corsac helps organizations conduct phased RPG-to-Java conversion without ground-up rewrite. We minimize maintenance costs and dependence on RPG specialists.
While decomposing a tightly coupled RPG code into modular Java architecture, we preserve critical business logic and operational continuity.
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Maintenance costs keep rising; constant fixes drain your budget
Even minor updates require risky changes across the entire system
Your core operations depend on a shrinking pool of RPG talents
Your scalability is limited by outdated, rigid architecture
Integrating with modern APIs, cloud services, and third-party tools is too challenging
Even small changes to older RPG programs can cause unexpected consequences. This happens when calculations, database access, and screen handling often share the same code in fixed-format RPG III with numbered indicators and in free-format RPGLE.
Corsac separates responsibilities, turning pricing rules, input checks, and stock calculations into independent Java components that are easy to test and update.
When core business operations, such as order management and accounting, depend on IBM i applications, moving them all at once can disrupt connected systems and confuse employees.
Corsac moves an application all at once when its dependencies are limited and risks are low. Otherwise, engineers migrate module by module, keeping the remaining RPG programs running and exchanging data with the new Java modules, thereby controlling cost and timing and keeping operations running.
Overnight jobs often prepare data that employees need at the start of the next working day.
Corsac moves CL programs and batch jobs to Java and suitable scheduling tools, keeping the correct task order, job parameters, and error-handling rules. Engineers also account for what CL programs set up around the RPG code, such as library lists, file overrides, and data areas, so each job runs with the same data and settings as before.
Part of RPG database logic is embedded SQL, and part is native record-level access through operations like CHAIN and READE, which read records in key order. Just copying SQL queries when moving database logic from RPG to Java isn’t enough. Since databases can handle data types, empty values, and updates differently, a query without explicit sorting rules can return records in a different order and break reports that total by group.
Corsac adapts embedded SQL, queries, updates, and transaction logic to the target database when transferring to Java. The team checks for differences, reducing the risk of data errors.
Employees who have worked in AS/400 green screens for years rely on a fixed field order and function keys to enter data quickly.
Corsac can replace display files with Java web interfaces as part of RPG to Java conversion. Engineers consider how employees use screen fields and function keys, so the new screens are clearer and simpler for data entry without slowing down daily work.
Other systems and employees often read IBM i printer-file reports, and systems may expect an exact layout.
Corsac moves them to current reporting tools and can keep existing report layouts and calculations in their original format when needed, so connected applications keep receiving data they can process.
With over 18 years of experience in software modernization, we help organizations conduct RPG to Java transition with minimal risks and long-lasting outcomes. Check the results below.
Antibiotic Susceptibility Test Time
72h → 3hAI Bacterial Classification Accuracy
95%
Reduced device setup time
60%Reduced memory use
38%Corsac combines strong legacy RPG and modern Java expertise, technical skills, and a business-oriented approach to address complex modernization challenges.
Reduce operational costs by improving maintainability
Accelerate delivery of new features to outpace competitors
Ensure better security and compliance
Enhance scalability
Get consistent, reliable data to support confident business decisions
Eliminate dependence on scarce expertise and expensive aging licenses
Keep customer operations running smoothly during transition
Help internal teams focus on strategic tasks and innovation
Replace a rigid monolithic architecture with a flexible, scalable system
Eliminate tech debt and provide a clean, reliable codebase
Create well-structured documentation
Enhance data consistency
Ensure smooth integration with modern APIs and platforms
Implement CI/CD pipelines for faster, automated delivery
Reduce migration risk thanks to canary deployments
Validate functional equivalence through automated and manual testing
Make your system cloud-ready
Let us help you rebuild what’s holding you back.
With Corsac, your RPG to Java transition will be well-planned, low-risk, and built around your strategic business growth. We’ll ensure your operational continuity while enhancing architecture, accelerating delivery, and driving innovation.
We aren’t a full-stack agency. We’ve built our team, processes, and tech strategy specifically to tackle legacy issues and help mid-market players scale and innovate.
We integrate with your workflows, minimizing interference with your developers. While utilizing your Git, CI/CD, and tools, we operate independently, letting your team focus on their work.
Your aging system drains your business resources through slow hiring, security gaps, and delayed launches. We reduce these “dark tech debt” losses before they impact your revenue.
We remove legacy barriers preparing your systems for advanced tech. You can embrace new tools with the future-ready and ROI-driven architecture.
Modernization efforts will be ineffective if the core issue is institutional rigidity. We reveal hidden limits and help grow with flexibility.
We treat your system efficiently: evolve the functioning parts and replace only the ones that require change.
Older RPG applications often contain undocumented logic and connections with other IBM i components. They may also handle numbers, dates, and scheduled jobs differently from Java applications. Corsac examines how the current system works before moving RPG to Java, to prevent calculation errors and processing failures.
Issue: Legacy RPG programs may hide dependencies that no one has written down. One program may calculate an order price, while another uses it to update stock. Without addressing those connections, developers can break critical functions.
Solution: Corsac investigates which programs depend on one another and where calculations take place. Before moving RPG to Java, the team understands what must stay the same and which connected parts need change. This planning allows Java RPG code conversion to preserve the original behavior.
Issue: RPG and Java can handle numbers and dates differently. Dates kept as numbers, such as CYYMMDD, can be misread, and rounding at a different step changes the total.
Solution: Corsac checks how numbers are stored and calculated and how RPG handles dates and empty fields. The Java code uses BigDecimal with the same precision and rounding. The team compares results with the original calculations to remove mismatches.
Issue: Many IBM i applications run jobs at established times, and later jobs may depend on earlier ones. If the Java system mixes the order or addresses a failed job differently, later steps may use incomplete information.
Solution: Corsac identifies job dependencies and moves CL-based control logic and batch processing to Java and suitable scheduling tools. Engineers check job sequence and parameters, failure handling, and restart procedures, to help teams investigate and restart failed jobs safely.
Issue: RPG applications often update several related records in one operation. An order may require saving its details, reducing inventory, and recording payment. If some of these changes aren’t saved, the database will store inconsistent information.
Solution: Corsac studies how the original application groups database operations and addresses errors. During migration, the team uses an RPG to java conversion tool and adjusts the Java code to handle database transactions, including programs that work without commit control. The Java code then defines transaction boundaries, so that related updates succeed or roll back together, preventing partial updates.
Issue: The Java application may repeat work the RPG program did once, like querying each record separately instead of reading them in sequence. This slows operations and loads the server.
Solution: Corsac compares the Java application’s results and processing times with the original system. Engineers test common tasks under realistic workloads analyze and fix slow queries or unnecessary processing. The migrated application delivers the same results without longer waits for users.
We start with an in-depth analysis of your outdated system to uncover architectural constraints, infrastructure issues, security gaps, and hidden threats. Also, we assess migration readiness and outline modernization opportunities.
We create a prioritized, phased, risk-managed strategy with a tailored approach to your migration needs. Based on this, we decompose your tightly-coupled monolithic app into a scalable, cloud-ready Java architecture.
Improve code quality by removing redundancy, duplicated logic, and inefficiencies
Incrementally redesign the application into a scalable, modular Java architecture while validating business logic at each stage
Apply access controls and audit logging to meet your compliance requirements
Standardize and optimize the database using JPA/Hibernate and build integrations with retry logic, validation, and monitoring
Implement encryption, authentication, and other modern security practices
Thanks to a combination of automated and manual testing, we check both system health and its functional equivalence with the original RPG app. CI/CD pipelines enable fast deployment with minimized risks. We also continuously monitor the system, outlining ways for resource optimization.
Book an expert consultation to uncover gaps in your system. Let us modernize your business to its maximum potential.
We focus on modernization for companies unable to grow due to aging systems
We replace only what must be changed, protecting your investment and CTO’s credibility.
HIPAA, HL7/FHIR, SOC2, GDPR, ISO compliance is integrated into every stage.
Integrating into your Git, CI/CD, and workflow tools, we make modernization visible, testable, and traceable
We uncover hidden costs, feature delays, and security gaps and offer ways of their removal
By providing CEOs stakeholder-ready roadmaps and progress metrics, we enable well-grounded transformation
They fulfill your task without seeking to address the issue at the root
Dispersing the focus, they fail to meet specific Healthcare and other industry requirements
Generalized practices, regardless of the product, team, or business specifics
Initiate full rewrites instead of using the working parts and considering business context
Insufficient collaboration leads to poor handover, with documentation debt and weak enablement.
Development happens in isolation, prioritizing code delivery over actual business value.
First, RPG to Java migration helps you get rid of legacy constraints that affect your app performance and growth. Secondly, you can significantly reduce maintenance costs and invest in innovation instead of fixing recurring errors. Also, Java is a proven technology to accelerate your time-to-market and outpace your competitors.
Everything depends on the size and complexity of your project, your business requirements, strategic goals, and timeline. We always conduct a pre-migration audit to get a realistic view of the system, assess the modernization scope and depth, and choose the most optimal approach. Based on these insights, you can get more precise budget forecasts.
Yes. Not all applications built with RPG programming require radical redesign. You can move to Java at different levels, e.g., code refactoring, database migration, integration modernization. We introduce all the changes incrementally, so your system will be safeguarded from risky disruption.
Sure. We use AI-based tools to accelerate the modernization process and maximize its outcomes. It’s built on a Retrieval-Augmented Generation (RAG) architecture and powered by a Multi-Agent Swarm. It can cover a wide range of tasks, from legacy audit and strategy creation to generation of modernized code.
Yes. Our collaboration with a client does not end after delivery. We provide continuous system monitoring to ensure performance stability and optimize resources. Also, we offer expert training to transfer system knowledge and help your internal team manage the system independently.
