Reliability in Systems Development

Migration and modernisation

Getting a system out of proprietary captivity without stopping the operation, under a zero-divergence criterion against the legacy system.

We did it with our own system in 1992 and we are doing it again with NextSabi. The lesson both times is the same: the success criterion is not “programs converted”, it is that the new number matches the old one to the cent. Everything else — the language, the database engine, the cloud — follows from that.

What it includes

  • Reading and rescuing the current system’s rule catalogue
  • Literal translation, attribute by attribute, with the source line number alongside
  • Shadow mode: new system and legacy posting in parallel, with reconciliation
  • Intentional divergences listed and signed off by the business
  • Portability across database engines
  • Cutover and rollback plan