Mainframe
COBOL to Java, C#
& Cloud
Many organizations still run iSeries (AS400) systems with a mix of COBOL and RPG programs. This page explains the key steps and challenges involved in migrating COBOL-based ILE applications to Java or C#.
The COBOL ILE dialect is very close to standard IBM COBOL, with a few differences. These include enhanced screen management using DDS and data access to DB400 through VSAM-style APIs.
COBOL ILE programs often use DDS sub-files to define user screens. These are usually part of conversational applications built for client-server systems. Interaction with the screens follows the same logic as VSAM file access, using COBOL READ and WRITE statements.
SoftwareMining converts these conversational COBOL applications into an application-server framework. The DDS screen layouts are translated into JSP or XHTML pages that run on a standard web server. The generated HTML retains the familiar character-based appearance of the original AS400 interface, helping users transition smoothly to the new system.
As part of modernization, businesses can enhance these screens with a modern UI design. The translated Java or C# applications can also use new JSP or ASP pages without changing the business logic underneath.
In COBOL ILE, database access is handled through standard READ and WRITE operations on DB400 records (for example, SELECT RECORD ASSIGN TO database-record). The DB400 uses APIs similar to VSAM for keyed and indexed file access.
SoftwareMining translates these DB400 file definitions and data operations into Object-Relational data modules. These new modules use standard SQL to communicate with DB400 or other relational databases. The translated Java code can continue running on the original iSeries hardware while connecting to DB400, or it can be deployed on other platforms such as Windows, Linux, or Solaris.
This approach allows organizations to modernize incrementally - keeping data and business logic consistent while gaining the benefits of SQL-based access and easier maintenance.
Many AS400 and iSeries environments include both RPG and COBOL applications. SoftwareMining specializes in the automated modernization of COBOL systems, but it does not currently provide tools for RPG migration.
For projects that include RPG components, we recommend partnering with third-party vendors who focus on RPG-to-Java or RPG-to-.NET conversion solutions. These tools can complement SoftwareMining's COBOL migration framework for a complete modernization strategy.
SoftwareMining provides automated COBOL-to-Java and COBOL-to-C# translators that maintain full functional equivalence while generating clean, cloud-ready code. Our tools have been used by global enterprises to modernize AS400, IBM Z/OS, and mainframe COBOL applications.
Learn more about our COBOL to Java/C# conversion process or contact our team for an enterprise briefing.