For stateful Microservices, it is efficient to store state near compute for improved performance. Service Fabric natively integrates with a Microsoft technology called Reliable Collections to achieve collocation of compute and state for services deployed on it.

Reliable Collections can be thought of as a collection of state stores specifically designed for multi-computer applications. It enables developers to store state locally on a node within a Service Fabric cluster while assuring high availability, scalability, and low latency. For services running multiple instances, the state is replicated across nodes hosting different instances. Replication is the responsibility of the Reliable Services framework. This saves developers a significant amount of time and effort.

Reliable Services is also transactional by nature and supports asynchronous, non-blocking APIs. Presently, this technology supports two types of state stores – Reliable Dictionary, for storing key-value pairs, and Reliable Queues, a first-in-first-out data structure usually used for message passing.