ING Bank COBOL-to-Java Migration Case Study

Decommissioning the ING mainframe was challenging. With SoftwareMining's assistance, the project was successful. We've been running smoothly on Linux since Feb 2022.

- ING Product Owner

Overview of the Migration Project

Following detailed technical, cost, and risk assessments, ING decided to manage the modernization internally. Using SoftwareMining's COBOL-to-Java conversion tools, the bank seamlessly transformed its mainframe COBOL/CICS applications into modern Java code.

Because the system was mission-critical, maintaining identical functionality was essential. More than 2 billion transactions were processed during side-by-side testing to verify that both the COBOL and Java systems produced identical outputs. This extensive validation phase extended the project to 18 months, but ensured total reliability.

Continuity of the messaging architecture was also crucial. The translated Java system supported a gradual transition from IBM MQ messaging, allowing hybrid operation during testing and a smooth future migration to open platforms. SoftwareMining's libraries enabled these changes without modifying the translated codebase.

Thread safety and concurrency were another major focus. The Java system underwent intensive parallel transaction testing to confirm that concurrent user sessions did not interfere with one another.

The batch component also required matching performance with the original IBM mainframe. Using SoftwareMining's JCL-to-Unix shell conversion and Java SORT implementation, the bank achieved equivalent throughput and maintained nightly batch processing windows.

Benefits of Mainframe Modernization at ING Bank

• Significant cost reduction through the move from mainframe to private cloud infrastructure.
• Improved scalability and maintainability by replacing COBOL with object-oriented Java.
• Agile development and faster deployment cycles enabled by modern tools and frameworks.
• Enhanced security, logging, and monitoring using standard Java libraries such as Maven and Log4J.

Why ING Chose SoftwareMining

Project Considerations

The bank decided to conduct translation and testing entirely in-house, leveraging its experienced COBOL team and maintaining full control over data and systems. This strategy provided multiple advantages:

• Security: All code and data remained within ING's infrastructure.
• Direct control over migration schedules, costs, and risk management.
• Efficient Translation-Testing cycles: translating only what could be tested immediately.
• Feedback-driven improvements: change requests on generated code incorporated into subsequent translation runs.
• Seamless interoperability through SoftwareMining libraries that automatically handled EBCDIC and packed-decimal data conversions.
• MQ migration strategy supporting IBM MQSeries and other messaging systems.
• CICS-compatible support libraries enabling online transaction translation.
• Automated conversion of JCL scripts to Unix shell, fully integrated with the new Java application.
• Long-term strategy for DB2-to-SQL migration across all application layers.

For a complete overview of modernization stages and planning, see our Mainframe Modernization Strategy.

Mainframe COBOL Migration Related Papers

• Mainframe modernization
• COBOL to Java & C# / Cloud modernization road map
• Translation Example: CardDemo Java Runtime
• Translation Of CICS VSAM API to Java
• Migrating VSAM / ISAM datafiles
• From JCL to Unix / Windows Shell Scripts

See how it works