Table of Contents

Hub Invocations

NexNet supports several method invocation patterns between server and client. The source generator handles all proxy creation — you define interfaces, and the generator emits the invocation infrastructure.

Return Types

Nexus interface methods support three return types:

Return Type Behavior
void Fire-and-forget. The caller does not wait for completion. Use for notifications.
ValueTask The caller awaits completion but receives no return value.
ValueTask<T> The caller awaits and receives a return value from the remote method. 
public interface IServerNexus
{
    void Notify(string message);                    // Fire-and-forget
    ValueTask UpdateAndWait(int id, string data);   // Await completion
    ValueTask<int> GetStatus(int userId);           // Await with result
}

Method Invocation Compatibility

Some argument types have restrictions on how they can be combined. The source generator enforces these rules with compile-time diagnostics.

CancellationToken INexusDuplexPipe INexusChannel<T> Args
void X
ValueTask X X
ValueTask X X X
ValueTask<T> X X

Rules:

  • CancellationToken cannot be combined with INexusDuplexPipe or INexusChannel<T> because pipes and channels have built-in cancellation/completion notifications.
  • CancellationToken must be the last parameter, following standard .NET conventions.
  • The total serialized argument size cannot exceed 65,535 bytes. For larger data, use Duplex Pipes or Channels.

Cancellation

Methods that return ValueTask or ValueTask<T> can accept a CancellationToken as the last parameter:

public interface IServerNexus
{
    ValueTask<byte[]> DownloadFile(string path, CancellationToken ct);
}

Cancelling the token on the caller side propagates the cancellation to the remote method.

Server Broadcasting

The server can invoke methods on multiple connected clients with a single call through the session context:

[Nexus<IServerNexus, IClientNexus>(NexusType = NexusType.Server)]
partial class ServerNexus
{
    public async ValueTask BroadcastStatus(int status)
    {
        // Send to all connected clients
        await Context.Clients.All.OnStatusChanged(status);

        // Send to a specific group
        await Context.Clients.Group("room-1").OnStatusChanged(status);
    }
}

See Also

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