Deconstructing Legacy Core Accounting Mainframe to Microservices
Migrating legacy high-throughput core transaction ledger databases to a cloud-native distributed microservice platform using the Strangler Fig pattern.
The Challenge
The client relied on a legacy mainframe system for core accounting processing, incurring massive licensing fees, developer talent shortages, and high transaction constraints. The system handled millions of updates daily. Due to operational risks, a big-bang cut-over was ruled out. We needed to strangulate and migrate core domains to cloud services incrementally without introducing consistency defects.
Architecture and Operational Alignment
Deconstructed Domain Architecture
The Solution
We established a Strangler Fig migration strategy. We deployed API proxy layers to route live traffic between the legacy mainframe and modern microservices. Dynamic Change Data Capture (CDC) pipelines synchronized write actions bidirectionally. By isolating domains (Customers, Policies, Claims) one-by-one, we completely decommissioned mainframe modules, reducing reliance on obsolete infrastructure.
Data Footprint Decommissioning Progress
Performance Metrics (KPIs)
| Key Performance Indicator (KPI) | Target | Actual Result | Status |
|---|---|---|---|
| Accounting System Throughput | > 5x higher | 6.2x higher | Target Exceeded |
| Mainframe MIPS Usage | > 80% reduction | -90% MIPS | Target Exceeded |
| Database Sync Latency | < 200 ms | 84 ms | Highly Responsive |
| Ledger Reconciliation Defects | 0 errors | 0 errors | Perfect Consistency |