Apache Pulsar - Distributed pub-sub messaging platform

Pulsar is a distributed pub-sub messaging platform with a very flexible messaging model and an intuitive client API. It has run in production at Yahoo scale for over 3 years, with millions of messages per second across millions of topics. It is Horizontally scalable, Low latency, High throughput, Multi-tenancy, Geo-replication, Transparent batching of messages, Transparent handling of partitioned topics, REST API for provisioning, admin and stats and lot more.