Siphon is a highly available and reliable distributed pub/sub system built using Apache Kafka. It is used to publish, discover and subscribe to near real-time data streams for operational and product intelligence. Siphon is used as a “Databus” by a variety of producers and subscribers in Microsoft, and is compliant with security and privacy requirements. It has a built-in Auditing and Quality control. This session will provide an overview of the use of Kafka at Microsoft, and then deep dive into Siphon. We will describe an important business scenario and talk about the technical details of the system in the context of that scenario. We will also cover the design and implementation of the service, the scale, and real world production experiences from operating the service in the Microsoft cloud environment.