How Reaqtor combines reactivity with reliable data processing

Reaqtor is an evolution of Rx and is used to power services in Bing, Cortana & M365. In order to support the long-running nature of some of the queries involved in these processes, it must be able to survive process restarts and even total migrations. It does this by persisting the current state of the system via "checkpointing", enabling queries that can run for days, weeks, months, or even years!