System Calls

For Information Only

This section documents the internal system call interfaces used by ActualLab.Rpc and Fusion. You should never send these calls manually – they are automatically invoked by the framework to manage RPC communication, call lifecycle, streaming, and computed value invalidation.

Understanding these calls may be helpful for debugging, extending the framework, or understanding the wire protocol.

IRpcSystemCalls

IRpcSystemCalls is the core system service interface (service name: $sys) that handles RPC infrastructure operations. All methods use fire-and-forget semantics via RpcNoWait where appropriate.

Handshake & Reconnection

Method	Arguments	Description
Handshake	RpcHandshake handshake	Initiates connection handshake between peers
Reconnect	int handshakeIndex, Dictionary<int, byte[]> completedStagesData, CancellationToken	Handles reconnection after network interruption

Call Lifecycle

Method	Arguments	Description
Ok	object? result	Returns successful call result to the caller
Error	ExceptionInfo error	Returns error information to the caller
Cancel	(none)	Cancels an in-progress call
M	(none)	Signals a "match" (cache hit) for Compute Service calls
NotFound	string serviceName, string methodName	Indicates the requested service/method doesn't exist

Object Lifecycle

Method	Arguments	Description
KeepAlive	long[] localIds	Keeps remote objects alive (prevents garbage collection)
Disconnect	long[] localIds	Disconnects/releases remote objects

Stream Control

Method	Arguments	Description
Ack	long nextIndex, Guid hostId	Acknowledges received stream items (flow control)
AckEnd	Guid hostId	Acknowledges stream completion
I	long index, object? item	Sends a single stream item
B	long index, object? items	Sends a batch of stream items
End	long index, ExceptionInfo error	Signals stream completion (with optional error)

IRpcComputeSystemCalls

IRpcComputeSystemCalls is a Fusion-specific system service interface (service name: $sys-c) that handles computed value invalidation propagation.

Method	Arguments	Description
Invalidate	(none)	Notifies the client that a computed value has been invalidated on the server

This single call is the mechanism that enables real-time UI updates in Fusion. When a server-side Computed<T> is invalidated, the server sends an Invalidate call to all connected clients that have replicas of that computed value. This triggers re-computation on the client side, which in turn updates any dependent UI components.