Architecture around the ABS: modernisation without replacing the core
Replacing ABS — 24-36 months and operational risk. Wrap around it — in 6-12 months. Architectural approach for banks with legacy core.
Discuss Your ChallengeWhy wrap rather than replace
Most banks in UZ have a legacy ABS (CFT, Forte, RS-Bank, in-house) 10-20 years old. Replacement — major capital project (24-36 months, $20-100M, operational risk). Regulator cautious about mass migrations.
Wrap: keep ABS as system of record, but build a modern integration layer around it — API, event streaming, modern channels, decisioning. Business velocity grows without core disruption.
Wrap structure
API gateway. All internal and partner integrations through a single layer. Auth, rate limiting, monitoring.
Event bus. ABS → events → multiple consumers (CDP, fraud, risk, channels). ABS remains source of truth, but downstream consumers do not poll the database.
Adapter layer for legacy. Converts legacy ABS data formats → modern (JSON, Protobuf). One-way isolation from ABS change cycles.
Modern decisioning layer. Real-time decisions (fraud, NBA, credit) running outside ABS, calling into ABS only to commit transactions.
Customer-facing applications. Mobile, web, partner — built on modern stack, via API layer rather than directly to ABS.
Where it usually breaks
Adapters written for one use case, then expanded ad-hoc. Two years later — entanglement spaghetti.
Event bus without contracts — schema changes break consumers silently.
API gateway not enforced — some consumers still hit ABS directly, bypassing the layer.
ABS vendor cooperation absent — each core modification (for event output) requires expensive change requests.
Performance bottleneck — ABS not designed for real-time event emission, latency growing.
What is needed for a successful wrap
API ownership clear (Head of Platform / CTO office).
Event taxonomy and contracts strict.
Adapter team as a dedicated function — not a side project.
Vendor partnership with ABS provider — invest in their parallel modernisation.
Migration plan for core transition when regulator / business demand finally requires it.
Related
- /en/decisions/banking-build-vs-buy-sme/ — build vs buy
- /en/architecture/banking-event-bus-architecture/ — event bus
- /en/architecture/banking-partner-api-platform/ — partner API
- /en/insights/banking-core-modernization/ — core modernisation
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