Apache Pulsar

Event streaming is a sequence of events, meaning order between events matters, think audio/video streams. Events flow through the system in a specific direction: from producers to consumers. Event streaming is an implementation of the pub/sub architectural pattern.  

Apache Pulsar is a cloud-native distributed messaging and streaming platform. Pulsar provides a high-performance solution for server-to-server messaging and geo-replication of messages across clusters. It offers a simple client API with bindings for Go, Java, C++, and Python. Pulsar can be used when developing event-based services, realtime filtering and simple (extract, transform, and load) ETL operations. 

You can use a Pulsar rule if you want to send data such as messages, occupancy, lifecycle and presence events from Ably to Pulsar.