What the client was up against.
Northwind's claims core was a monolithic mainframe extension running a quarter of its annual premium through batch windows.
Business agility was measured in quarters, not sprints, and change risk made even mandatory regulatory updates expensive.
A full replatform had been attempted — and abandoned — twice before.
What we built, and how.
BNS decomposed the core along domain lines and introduced an event mesh that allowed legacy and modern services to co-exist.
Each domain was rebuilt behind strangler facades, with automated parity testing against the legacy system before any traffic was cut over.
Release trains moved from quarterly to biweekly, protected by feature flags, error budgets and automated rollback criteria.
How the program ran.
- Phase 01
Discovery
Domain mapping, reference architecture, success metrics signed-off with the business and regulator.
- Phase 02
Foundations
Landing zone, CI/CD, event mesh and observability baseline delivered inside 90 days.
- Phase 03
Decomposition
Claims intake, adjudication, payments and communications rebuilt domain-by-domain.
- Phase 04
Cutover
Shadow-running against the legacy for three months, then wave-based customer cutover with automated reconciliation.
Things we're especially proud of.
- Reference architecture
Three tiers, four domains, policy-as-code at every boundary.
- Release discipline
Biweekly trains with SLO and error-budget gating.
- Hand-back
Northwind now runs the platform; BNS supplies continuous modernisation.
“They rebuilt the engine of our business while the aircraft kept flying. I've never seen an integrator own the outcome like BNS did.”