Migrating COBOL Apps

Learn about the challenges of migrating legacy COBOL applications to modern environments, and get tips for doing so smoothly.

Introduction

• Succeed with a COBOL migration
• What you should know

1. The Case for Migrating COBOL

• COBOL today
• GAO, legacy systems, and COBOL
• Approaches to legacy migration
• Reasons for migration success and failure
• Migrate to the cloud

2. Using COBOL

• Install a Linux subsystem on Windows
• Run GnuCOBOL on Linux
• Look at code from the past
• Measure code complexity
• Different dialects of COBOL

3. Challenges for the Migration

• Self-modifying code
• Dynamic calls to subprograms
• Understand XA transactions
• The buried update
• The deadly embrace
• Legacy control flow
• Challenge: Trace the control flow
• Solution: Trace the control flow

4. Analysis of COBOL Source Code

• Lehman's laws of software evolution
• Reengineer and the horseshoe model
• Classification of legacy data
• The reengineering process
• Visualization of legacy COBOL code
• Create COBOL flowcharts with Visustin
• Navigate code visually with Visual Studio

5. Refactoring and Resizing

• Prepare to refactor code
• Refactor the DESR application
• Remove redundant labels
• Resize applications
• Make code segments generic
• Challenge: Refactoring
• Solution: Refractoring
• Introduce structure through subprograms
• Remove dead code
• Refactor data
• The challenges of migrating to a relational database
• Refactoring, continuous integration, and self-testing
• Observations on the paradigm shift
• The refactoring catalog

6. An Exercise in Migration

• P6 application
• Select the migration option
• Understand the P6 application
• Introduction to QWICS
• Explore the online QWICS demonstrator
• Migrate P6 into QWICS
• Start the P6 PRIMA migration
• Architecting the P6 database
• Migrate the P6 data
• Create the data access layer
• Migrate the P6 code

Conclusion

• What's next