Mainframe
COBOL to Java, C#
& Cloud
Data migration is a critical part of modernizing COBOL applications to Java or C#. While code translation often takes center stage, legacy data structures such as VSAM KSDS files can present equal or greater complexity. This page outlines practical strategies for migrating these "base COBOL" applications - typically built around flat file I/O and record-based logic-into scalable, maintainable Java or C# systems.
SoftwareMining provides a structured approach to COBOL data migration as part of its broader Java and C# modernization services. Sequential and SQL-based data are preserved where possible, while VSAM and indexed files are refactored into object-relational structures and integrated with standard SQL databases. Specialized handling is also available for IMS-DB, DMS-II, and other non-relational platforms.
Each COBOL data source introduces unique challenges. The sections below describe how SoftwareMining manages data migration across common formats and platforms.
Many COBOL systems still depend on VSAM KSDS files for core data management. A structured migration begins by aligning each COBOL FILE-DEFINITION with a relational schema. SoftwareMining automatically generates SQL DDL from COBOL structures or from CICS WORKING-STORAGE sections used in EXEC CICS Read/Write operations.
Once the schema is defined, Java Data-Access Objects (DAOs) and SQL migration scripts ensure consistency between program logic and data structures. For best results, database design and access layers are tuned for performance and scalability.
Performance Note: SQL databases handle large data volumes well, but latency can rise with frequent small reads. Optimizing connection pooling, batching, and schema design is key for maintaining mainframe-grade performance.
Sequential files are often used for temporary storage, sorting, and reporting. By default, they remain as files for backward compatibility but can also be migrated to SQL databases. SoftwareMining-generated sequential files provide:
Relative files can be preserved as system files or restructured into relational tables, depending on usage patterns and required access performance.
In online environments, COBOL programs often access VSAM files through EXEC CICS commands. SoftwareMining automates the translation of these embedded CRUD operations (Create, Read, Update, Delete) into equivalent Java or C# logic, preserving transactional consistency.
See also:
IMS-DB is a hierarchical database widely used in high-volume COBOL systems. Migration requires accurate handling of parent-child relationships and DL/I API calls. SoftwareMining supports automated schema mapping and API translation.
Unisys environments rely on CODASYL, DMS-II, or DMS-2200 databases. Each requires a custom mapping and transformation path. SoftwareMining offers tailored support for converting these data models into SQL-compatible schemas.
IBM iSeries (AS/400) systems using ILE COBOL often combine DDS-based files with subfile-driven screen logic. SoftwareMining supports automatic translation of these file and screen structures into modular Java or C# code.
In many COBOL systems, different programs define slightly different FILE-DEFINITION layouts for the same dataset. This inconsistency complicates mapping to relational schemas. Manually reconciling these differences is slow and error-prone. SoftwareMining's automated analysis identifies and consolidates these structures to ensure one consistent data definition for migration.
Batch programs and data-intensive processes require high runtime efficiency. Key performance-related factors include: