This subproject provides an API (possibly as spec) and backends for journaled streams of events. These extend the publish/subscribe model with means to start consume from an point in the stored event stream history.
- Provide traditional publish / subscribe semantics
- Allow consuming a stream from any point in the history (given it is not yet evicted)
Non goals (to be discussed)
- No coverage of extreme scaling like Apache Kafka. So no sharding support in the API (like partitions).
- Messages sent to a topic must be journaled and must be available to all consumers
- Consumers must be able to start consuming messages from any point in the history that is still available
- If a consumer specifies a position that is not available anymore then it must start with the oldest message
- Each consumer must receive messages in the same order they were sent
- The journal of each topic may evict messages that are older than a certain retention time