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Bridging decades of legacy with modern cloud.

Pension companies run on systems built over decades — mainframes, core policy systems, payment platforms. These systems work, but they were never designed to talk to each other or to modern applications. I built the serverless middleware layer that makes it all connect.

AWS LambdaSQSAPI GatewayS3CloudFormation

The architecture

Event-driven, serverless, and designed for resilience. Lambda functions handle the business logic, SQS queues buffer between systems with different processing speeds, EventBridge routes events to the right consumers, and API Gateway provides clean REST interfaces for the frontend and workflow engine. Everything is defined as infrastructure-as-code with CloudFormation.

What it connects

The core pension administration system (the mainframe-era heart of the business), multiple legacy policy management systems, external banking partners for payment processing, tax authority integrations, and the modern Camunda workflow engine. Each integration is its own Lambda function with its own error handling, retry logic, and dead-letter queue.

Scale and reliability

The layer processes thousands of transactions daily — from small data lookups to complex multi-step payment flows. Every message is tracked, every failure is captured, and nothing gets lost. When a downstream system is slow or down, SQS holds the messages until it recovers. When a Lambda fails, it retries with exponential backoff before landing in a dead-letter queue for manual review.

Why serverless

A pension company doesn't need to run servers 24/7 for integrations that spike during business hours and flatline at night. Serverless means we pay for what we use, scale automatically, and never worry about patching or capacity planning. The operational overhead went from managing servers to monitoring CloudWatch dashboards.

Results

  • Connected mainframe, legacy, and modern systems through a single integration layer
  • Thousands of daily transactions with built-in retry and dead-letter handling
  • Infrastructure-as-code — every environment is identical and reproducible
  • Cost-efficient serverless model matching actual usage patterns

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© 2026 Philip Christian Juhl