Legacy API Reference

Archived and unsupported. This material is retained only to help migrate existing applications. There is no new Legacy release line, feature or compatibility work, or security fixes. New development must use the current functional API.

Reference for the original Orleans.FSharp authoring APIs kept for existing applications.

This page records the 4.1-and-earlier surface for migration. It is not a supported or newly released 5.0 API.

Orleans.FSharp.EventSourcing

The historical eventSourcedGrain { } CE and its JournaledGrain bridge are not the same thing as the current journaledGrainFor definition builder. The old path depended on the archived CodeGen source bridge; neither project is published in the 5.0 package set. See Event Sourcing.

Types

Type	Description
EventSourcedGrainDefinition<'State, 'Event, 'Command>	Event-sourced grain specification (DefaultState, Apply, Handle, ConsistencyProvider, CustomStorage, SnapshotStrategy)
SnapshotStrategy<'State>	Never, Every of int, Condition of (int -> 'State -> bool)
CustomStorageAdapter	Boxed read/write pair for a custom log-consistency store
IEventStoreContext<'Event>	Event store abstraction for the C# CodeGen bridge (RaiseEvent, ConfirmEvents, Version)
FSharpEventSourcedGrain<'State,'Event,'Command>	Generic JournaledGrain base bridging a definition to Orleans
FSharpEventSourcedGrainAttribute	Binds an implementation to a grain interface

Computation expressions

CE	Builder	Description
eventSourcedGrain { }	EventSourcedGrainBuilder	Define event-sourced grain behavior

eventSourcedGrain { } — keywords

Keyword	Signature	Description
defaultState	'State	Initial state value
apply	'State -> 'Event -> 'State	The pure fold
handle	'State -> 'Command -> 'Event list	Command handler; an empty list is a refusal
logConsistencyProvider	string	Named Orleans log-consistency provider
snapshot	SnapshotStrategy<'State>	Snapshot strategy (honoured only by a custom store)
customStorage	read + write	Custom log-consistency storage pair

EventSourcedGrainDefinition

Function	Signature	Description
foldEvents	definition -> 'State -> 'Event list -> 'State	Replay events onto state
handleCommand	definition -> 'State -> 'Command -> 'State * 'Event list	Process a command, returning the folded state and the events

EventStore

Function	Signature	Description
processCommand	definition -> 'State -> 'Command -> 'Event list	Produce events from a command
applyEvent	definition -> 'State -> 'Event -> 'State	Apply a single event
replayEvents	definition -> 'State -> 'Event list -> 'State	Replay an event list
shouldSnapshot	definition -> int -> 'State -> bool	Evaluate the snapshot strategy

Registration

Method	Signature	Description
AddFSharpEventSourcedGrain<'State,'Event,'Command>	IServiceCollection -> definition -> IServiceCollection	Register one definition
AddFSharpEventSourcedGrainsFromAssembly	IServiceCollection -> Assembly -> IServiceCollection	Register every definition an assembly declares

---

Deprecated: the grain { } cluster

Everything below carries [<Obsolete>] (warning, not error) and is kept runnable. The replacement for each entry is the functional grain runtime; see API Migration for the rewrite recipe.

Types

Type	Description	Replacement
GrainDefinition<'State, 'Message>	Immutable record describing a grain’s behavior	FunctionalGrainDefinition<...> from grainFor
GrainContext	Grain factory, service provider, and named states	FunctionalGrainContext<'Actor,'Key>
AdditionalStateSpec	Named additional persistent state specification	PersistentState.create + usePersistentState
FSharpGrainAttribute	Marks a definition for assembly discovery	— (a definition is registered by value)
FSharpGrainHandle<'S,'M>	Zero-alloc struct handle for a string-keyed grain	FunctionalGrain.ref / rawRef
FSharpGrainGuidHandle<'S,'M>	Zero-alloc struct handle for a GUID-keyed grain	FunctionalGrain.ref / rawRef
FSharpGrainIntHandle<'S,'M>	Zero-alloc struct handle for an int64-keyed grain	FunctionalGrain.ref / rawRef

Computation expressions

CE	Builder	Description
grain { }	GrainBuilder	Define grain behavior declaratively

grain { } — key CE keywords

Keyword	Handler Signature	Description
defaultState	'State	Initial state value
handle	'State -> 'Msg -> Task<'State * obj>	Register handler with manual box
handleState	'State -> 'Msg -> Task<'State>	Handler returning only state (no result value)
handleTyped	'State -> 'Msg -> Task<'State * 'R>	Handler with typed result — no box needed
handleWithContext	GrainContext -> 'State -> 'Msg -> Task<'State * obj>	Handler with DI/grain-to-grain access
handleStateWithContext	GrainContext -> 'State -> 'Msg -> Task<'State>	Context + state-only return
handleTypedWithContext	GrainContext -> 'State -> 'Msg -> Task<'State * 'R>	Context + typed result
handleCancellable	'State -> 'Msg -> CancellationToken -> Task<'State * obj>	Cancellation, manual box
handleStateCancellable	'State -> 'Msg -> CancellationToken -> Task<'State>	Cancellation, state-only return
handleTypedCancellable	'State -> 'Msg -> CancellationToken -> Task<'State * 'R>	Cancellation, typed result
handleWithContextCancellable	GrainContext -> 'State -> 'Msg -> CancellationToken -> Task<'State * obj>	Context + cancellation
handleStateWithContextCancellable	GrainContext -> 'State -> 'Msg -> CancellationToken -> Task<'State>	Context + cancellation, state-only return
handleTypedWithContextCancellable	GrainContext -> 'State -> 'Msg -> CancellationToken -> Task<'State * 'R>	Context + cancellation, typed result
persist	string	Name of the storage provider for state
additionalState<'T>	string (name) + string (storage) + 'T (default)	Named additional persistent state
onActivate	'State -> Task<'State>	Activation hook; may replace the state
onDeactivate	'State -> Task<unit>	Deactivation hook; cleanup only
onReminder	string + ('State -> string -> TickStatus -> Task<'State>)	Named reminder with a stateful handler
onTimer	string + TimeSpan (due) + TimeSpan (period) + ('State -> Task<'State>)	Declarative timer
onLifecycleStage	int + (CancellationToken -> Task<unit>)	Hook a raw Orleans grain-lifecycle stage number
interleaveMessage	System.Type	Allow a message type to interleave (interleaveMessage typeof<Query>)

Each handle* keyword also has a *WithServices form (handleWithServices, handleStateWithServices, handleTypedWithServices, and their Cancellable variants) taking an IServiceProvider instead of a GrainContext. See legacy Grain Definition guide for the full keyword list. In the historical model, per-grain Orleans attributes ([Reentrant], [StatelessWorker], placement, [OneWay], [ReadOnly], [ImplicitStreamSubscription], …) were applied to application-owned C# grain classes or methods, not expressed as grain { } keywords. The retained repository generator does not generate ordinary GrainDefinition classes. On the functional grain runtime they are ordinary contract and definition operations instead — reentrant, statelessWorker, placement, oneWay, readOnly, and onStream / onBroadcast for implicit subscriptions.

Modules

GrainContext

Function	Signature	Description
getService<'T>	GrainContext -> 'T	Resolve a DI service
getState<'T>	GrainContext -> string -> IPersistentState<'T>	Get named additional persistent state
getGrainByString<'T>	GrainContext -> string -> GrainRef<'T, string>	Get grain ref by string key
getGrainByGuid<'T>	GrainContext -> Guid -> GrainRef<'T, Guid>	Get grain ref by GUID key
getGrainByInt64<'T>	GrainContext -> int64 -> GrainRef<'T, int64>	Get grain ref by int64 key
getGrainByGuidCompound<'T>	GrainContext -> Guid -> string -> GrainRef<'T, CompoundGuidKey>	Compound GUID key
getGrainByIntCompound<'T>	GrainContext -> int64 -> string -> GrainRef<'T, CompoundIntKey>	Compound int64 key
deactivateOnIdle	GrainContext -> unit	Request grain deactivation when idle
delayDeactivation	GrainContext -> TimeSpan -> unit	Delay grain deactivation
grainId	GrainContext -> GrainId	Get the GrainId
primaryKeyString	GrainContext -> string	Get string primary key
primaryKeyGuid	GrainContext -> Guid	Get Guid primary key
primaryKeyInt64	GrainContext -> int64	Get int64 primary key
empty	GrainContext	Empty context for unit tests (all fields null/None)

GrainDefinition

Function	Signature	Description
hasAnyHandler	GrainDefinition -> bool	True if any handler is registered
getHandler	GrainDefinition -> 'State -> 'Message -> Task<'State * obj>	Get plain handler
getContextHandler	GrainDefinition -> GrainContext -> 'State -> 'Message -> Task<'State * obj>	Get context-aware handler
getCancellableContextHandler	GrainDefinition -> GrainContext -> 'State -> 'Message -> CT -> Task<'State * obj>	Get cancellable context handler
invokeHandler	GrainDefinition -> 'State -> 'Message -> Task<'State * obj>	Invoke handler (C# interop)
invokeContextHandler	GrainDefinition -> GrainContext -> 'State -> 'Message -> Task<'State * obj>	Invoke context handler (C# interop)
invokeCancellableContextHandler	GrainDefinition -> GrainContext -> 'State -> 'Message -> CT -> Task<'State * obj>	Invoke cancellable (C# interop)
invokeOnActivate	GrainDefinition -> 'State -> Task<'State>	Run the activation hook directly
invokeOnDeactivate	GrainDefinition -> 'State -> Task	Run the deactivation hook directly
invokeReminderHandler	GrainDefinition -> 'State -> string -> TickStatus -> Task<'State>	Run one named reminder handler directly

Reminder

Removed. The obsolete Reminder.register / .unregister / .get helper is no longer part of the package. In current functional grains, declare durable recurring work with onReminder; when a handler needs imperative reminder access, resolve Orleans’ IReminderRegistry from context.services. Class grains should call Orleans’ Grain.RegisterOrUpdateReminder, Grain.UnregisterReminder, and Grain.GetReminder APIs directly.

Timers

Function	Signature	Description
register	Grain -> (CT -> Task<unit>) -> TimeSpan -> TimeSpan -> IGrainTimer	Register timer
registerWithState<'T>	Grain -> ('T -> CT -> Task<unit>) -> 'T -> TimeSpan -> TimeSpan -> IGrainTimer	Timer with state

Replacement: onTimer on a functional definition.

FSharpGrain — universal grain pattern

Registered once with AddFSharpGrain, called from anywhere with FSharpGrain.ref. Replacement: grainContract + grainFor + FunctionalGrain.ref, which types the reply per operation instead of boxing one message DU.

Function	Signature	Description
FSharpGrain.ref<'S,'M>	IGrainFactory -> string -> FSharpGrainHandle<'S,'M>	Handle for string-keyed grain
FSharpGrain.refGuid<'S,'M>	IGrainFactory -> Guid -> FSharpGrainGuidHandle<'S,'M>	Handle for GUID-keyed grain
FSharpGrain.refInt<'S,'M>	IGrainFactory -> int64 -> FSharpGrainIntHandle<'S,'M>	Handle for int64-keyed grain
FSharpGrain.send<'S,'M>	'M -> FSharpGrainHandle<'S,'M> -> Task<'S>	Send command, return typed state
FSharpGrain.post<'S,'M>	'M -> FSharpGrainHandle<'S,'M> -> Task	Fire-and-forget command
FSharpGrain.ask<'S,'M,'R>	'M -> FSharpGrainHandle<'S,'M> -> Task<'R>	Send command, return typed result (can differ from state)
FSharpGrain.sendGuid<'S,'M>	'M -> FSharpGrainGuidHandle<'S,'M> -> Task<'S>	Send to GUID-keyed grain
FSharpGrain.postGuid<'S,'M>	'M -> FSharpGrainGuidHandle<'S,'M> -> Task	Post to GUID-keyed grain
FSharpGrain.askGuid<'S,'M,'R>	'M -> FSharpGrainGuidHandle<'S,'M> -> Task<'R>	Ask GUID-keyed grain for typed result
FSharpGrain.sendInt<'S,'M>	'M -> FSharpGrainIntHandle<'S,'M> -> Task<'S>	Send to int64-keyed grain
FSharpGrain.postInt<'S,'M>	'M -> FSharpGrainIntHandle<'S,'M> -> Task	Post to int64-keyed grain
FSharpGrain.askInt<'S,'M,'R>	'M -> FSharpGrainIntHandle<'S,'M> -> Task<'R>	Ask int64-keyed grain for typed result

DI registration (call once per grain definition at silo startup):

// Automatically registers FSharpBinaryCodec (idempotent)
services.AddFSharpGrain<CounterState, CounterCommand>(counterGrain) |> ignore

AddFSharpGrainsFromAssembly registers every [<FSharpGrain>]-marked definition an assembly declares.

Testing helpers for the deprecated model

Function	Signature	Description
GrainMock.withFSharpGrain<'S,'M>	string -> GrainDefinition<'S,'M> -> MockGrainFactory -> MockGrainFactory	Register an F# grain definition as a mock, by string key
GrainMock.withFSharpGrainGuid<'S,'M>	Guid -> GrainDefinition<'S,'M> -> MockGrainFactory -> MockGrainFactory	The same, by GUID key
GrainMock.withFSharpGrainInt<'S,'M>	int64 -> GrainDefinition<'S,'M> -> MockGrainFactory -> MockGrainFactory	The same, by int64 key
TestHarness.getFSharpGrain<'S,'M>	TestHarness -> string -> FSharpGrainHandle<'S,'M>	Handle from a test cluster, by string key
TestHarness.getFSharpGrainGuid<'S,'M>	TestHarness -> Guid -> FSharpGrainGuidHandle<'S,'M>	The same, by GUID key
TestHarness.getFSharpGrainInt<'S,'M>	TestHarness -> int64 -> FSharpGrainIntHandle<'S,'M>	The same, by int64 key

Other compatibility helpers

The following helpers support C# CodeGen interfaces or the older class-based transactional model; they are not part of the functional authoring surface.

API	Purpose	Functional replacement
GrainRef.ofString/ofGuid/ofInt64 and GrainRef.invoke	Wrap a generated C# grain interface	FunctionalGrain.ref / rawRef
GrainState.read/write/clear/current	Operate directly on an injected IPersistentState	PersistentState.create, stateFrom, and context.persistentState
Observer.createRef/deleteRef/subscribe and FSharpObserverManager	Generated C# observer interfaces	observerContract, FunctionalObserver, and FunctionalObserverManager
Transactions.TransactionalState	Wrap an injected ITransactionalState	transactionalStateFrom and FunctionalTransactionalState

CodeGen interface versioning

These settings apply to Legacy C# CodeGen grain interfaces. Current functional contracts use version, acceptsVersions, and sinceVersion on grainContract instead.

API	Members
CompatibilityStrategy	BackwardCompatible, StrictVersion, AllVersions
VersionSelectorStrategy	AllCompatibleVersions, LatestVersion, MinimumVersion
Versioning	compatibilityStrategyName, versionSelectorStrategyName
TransactionalGrainDefinition, FSharpTransactionalGrain, AtmGrainDefinition, FSharpAtmGrain	Class-based transactional grains