Understanding Apache Pulsar's Two-Layer System. Apache Pulsar has two layers, a serving layer and a storage layer. The Pulsar brokers carry out the data serving. The BookKeeper bookies provide the storage.

Serving Layer: Role of Pulsar Brokers. Data is sent to Pulsar topics by producers, and read from Pulsar topics by consumers.

Multiple consumers can read from the same topic. For instance, a retail company might have a machine learning model and an alerting system both consuming messages from the same inventory database.

Each single partition topic has a single Pulsar broker that owns it. A topic with multiple partitions will be spread across many Pulsar brokers.

Continue reading about Pulsar's split serving and storage layers. https://dattell.com/data-architecture-blog/what-is-apache-pulsars-two-layer-system/