Scalable Annotation Service

Netflix has developed Marken, a scalable annotation service that allows any microservice to attach metadata (annotations) to their entities. Marken supports versioned annotations, real-time CRUD and search operations for UI applications, and offline analytics in Hive/Iceberg. It uses a flexible schema-based approach to define annotation data models, supporting various data types including geometry (WKT) and temporal information. The architecture leverages Cassandra for data storage and Elasticsearch for search capabilities, designed to handle high RPS and large data volumes.