Projects

Open-source Java libraries and demos I maintain on GitHub.

ASCIISafeCharsets

A CharsetProvider SPI that transliterates Unicode text into ASCII-safe subsets instead of rejecting or replacing non-ASCII characters. Four charset variants, including fixed-width record formats like ACH that require 1:1 character mapping.

RetryHTTP

HTTP-aware retry predicates and Retry-After header support for Resilience4j. Distinguishes responses that should be retried (e.g. 503) from those that shouldn’t (e.g. 200) while respecting server-requested delays.

Masking

Java wrapper types that protect sensitive data from accidental exposure in logs and toString() output. A Sensitive<T> base class with customizable Renderer implementations controls how much is revealed via format strings — useful for PII like SSNs and credit-card numbers.

KafkaGuaranteesLab

A Spring Boot application demonstrating the limitations of Kafka guarantees. It layers producer/consumer configuration with Resilience4j circuit breakers and retries to show how the guarantee is maintained end-to-end under failure. Kafka itself is configured for exactly once delivery using an idempotency key. The demo shows how this can greatly reduce the number of duplicate messages, but cannot eliminate them entirely without risking data loss.

RotatingSecrets

Zero-downtime database credential rotation for Spring applications in Kubernetes. HikariCP and Oracle UCP components watch mounted secret files and refresh pool credentials via a publisher-subscriber pattern, without disrupting existing connections.