Santanu Kar worked on the apache/pulsar repository, focusing on enhancing message reliability and data integrity within distributed systems. He addressed a critical issue where eventTime metadata could be lost during message redelivery and Dead Letter Queue (DLQ) processing. By ensuring eventTime was preserved across retry and DLQ lifecycles, Santanu reduced the risk of timestamp drift and potential downstream processing errors. His approach involved Java development and comprehensive test automation to verify timestamp consistency throughout the message lifecycle. This work strengthened Pulsar’s guarantees for consumers and auditing, demonstrating depth in messaging systems, event semantics, and robust testing practices within Java environments.