This article describes how Barclays implemented AWS Glue Schema Registry integration with AWS Lambda event filtering by customizing an open source library.

• Barclays needed schema validation for event-driven systems processing millions of transactions daily
• AWS Lambda event filtering didn't support Glue Schema Registry serialized payloads (non-JSON format)
• Default implementation prepends schema version ID as bytes, breaking JSON structure and filtering
• Solution: Add schema version ID as JSON metadata node instead of byte prefix
• Custom serializer extends default to inject schemaVersionId into metadata during encoding
• Custom deserializer retrieves schemaVersionId from JSON to load producer schema for decoding
• Maintains JSON compliance, enables Lambda filtering, and reduces unnecessary invocations and costs

Barclays leveraged the open source Glue Schema Registry library to create custom serialization/deserialization wrappers, enabling schema validation while preserving Lambda event filtering capabilities.