By migrating the mainframe or legacy to the cloud native, you are moving the workload to open system environments. The advantage is that there will be no change in the existing legacy program business logic. It is possible to effectively leverage critical data, enjoy a flexible, transparent and modern environment and save money on mainframe contracts.
- Old application logic – poor documentation
- Trying to reverse engineer COBOL, PL/I, Assembler, JCL, Easytreave, IDMS, DB2, IMS..
- Tightly coupled and brittle architecture
- Expensive upkeep (licensing & maintenance)
- Unable to re-host or offload in batch
- Desire to modernize
Rewrite – Migrate the data off the mainframe and completely rewrite the business processes in modern frameworks. Change the source language of the original application, for example, from COBOL or Natural to Java or C#.
Re-host – “Lift and Shift” the applications and data from the mainframe to Unix or Windows with interface emulation or automatic code translation tools.
ReInterface – Keep the business logic on the mainframe in its present form, but unlock them by exposing via REST API’s and Web Services.
Replace/Retire – Replace the business processes with packaged applications such as SAP, PeopleSoft and Oracle. This involves gap analysis and data conversion. Take an inventory of applications and retire those that no longer serve a purpose.
Here is a table to compare the maturity of various approaches
We recommend going by a phased delivery with accelerated tools and partners. This would mean co-hosting with the mainframe with re-platform tools for code migration. A gradual release to fully domain based microservices environment.
Re-platforming > by automating code conversion
Phases of delivery – Phase 1
Phases of delivery – Phases 2-4
Point-of-view on alternative approach
Alternative approaches for Re-hosting, Batch job migration, and Re-Engineering