Extensions

Azure functions extensions

There are three extensions added in the TheLongRun.Common library to make it easier to build a CQRS and event sourcing based system over Azure Durable Functions: EventStream, Classifier and Projection.

Each is implemented using dependency injection and the IExtensionConfigProvider interface such that they can be passed into Azure Functions as attributed parameters and the creation will be taken care of by the webjobs runtime environment.

EventStream

This allows for a specific event stream instance to be created to which a function can append events. The attribute takes the DomainName, AggregateTypeName and InstanceKey properties by which the event stream can be uniquely identified.

Projection

This allows for the creation of a projection that can be run over an event stream to turn the stream of events into a projected state as at a given point in time (or as of the latest event on that stream if no end date/time is specified)

Classifier

This allows for the creation of a classifier that can be run over an event stream to turn the stream of events into a in-or-out state for an identifier group as at a given point in time (or as of the latest event on that stream if no end date/time is specified)