Stateful Services in Service Fabric

Managing state reliably in a distributed system is a challenge. Service Fabric rises to the challenge. The key hazards of a distributed system:

1. Messages can get lost

2. Failure of a node

3. Communication channel stalls

So when a stateful service needs to persist state, it must use a Reliable Collection! SF provides reliable Dictionaries and reliable Queues to serve this end.

Reliable data structures are distributed data structures but can be used as if they are local data structures.

Reliable collections are persisted by a Reliable State Manager component (which is represented by a class in the Microsoft.ServiceFabric.Data namespace which lives in the Microsoft.ServiceFabric.Data.dll in the Azure SDK).

The states are replicated by a Transactional Replicator to secondary replicas for availability and reliability.

Most stateful services inherit from a StatefulService class.