Subject
A subject is a Schema Registry identifier that groups versions of a schema governing a particular event type, topic, or key or value stream.
Kafka for Architects
A subject is a Schema Registry entity that groups versions of a data schema according to an event type, topic, or both.
- How it is used
- Decouples event domain models from Kafka topic organization while grouping schema versions.
- How deep it goes
- Explains mapping, version evolution, and compatibility, but does not detail all available subject strategies.
- Examples
- Uses a ClientEvent Avro schema on CLIENTS and ClientProfile V1/V2 compatibility scenarios.
- What you can do after
- Evaluate subject-to-topic strategies and govern schema evolution with compatibility modes.
Kafka Streams in Action, Second Edition
A subject name is a Schema Registry identifier that groups schema versions governing a particular stream key or value.
- How it is used
- Scopes schema versions and compatibility rules for Kafka record keys or values.
- How deep it goes
- Explains subject naming, registration, identifiers, version queries, and strategy trade-offs without detailing compatibility algorithms.
- Examples
- Uses avro-avengers-value, REST registration commands, schema ID 1, and AvengerAvro strategy configurations.
- What you can do after
- Operate/configure Schema Registry subjects through REST endpoints and select producer and consumer naming strategies.
Read how Kafka Streams in Action, Second Edition explains subject →
Related concepts
- schema registryconfigured by · A schema registry is a service that stores, versions, and provides schemas for structured data, often validating compatibility between schema versions.
- backward compatibilityconfigures · Backward compatibility is the property of a changed or newer system remaining usable by existing clients and consumers of its earlier interfaces, behavior, or data.
- topic name strategyused by · TopicNameStrategy is a Schema Registry subject-naming strategy that derives separate key and value subjects from a Kafka topic name.
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