Typed Methods

Call server methods through shared interfaces with full compile-time safety. The source generator produces proxy classes that handle serialization and method dispatch.

Get a typed proxy

Use GetTypedMethods<T>() to get a proxy for a shared contract interface:

var connection = HARRRConnection.Create(builder =>
{
    builder.WithUrl("https://localhost:5001/apphub");
});
await connection.StartAsync();

var chat = connection.GetTypedMethods<IChatHub>();

Call methods

The proxy maps interface method calls to the appropriate SignalARRR protocol message:

[SignalARRRContract]
public interface IChatHub
{
    Task SendMessage(string user, string message);    // fire-and-forget
    Task<List<string>> GetHistory();                   // invoke with result
    IAsyncEnumerable<string> StreamMessages(CancellationToken ct);  // stream
}

// Fire-and-forget (sends InvokeMessage)
await chat.SendMessage("Alice", "Hello!");

// Invoke with result (sends InvokeMessageResult, awaits response)
List<string> history = await chat.GetHistory();

// Stream (sends StreamMessage, returns IAsyncEnumerable)
await foreach (var msg in chat.StreamMessages(cancellationToken))
{
    Console.WriteLine(msg);
}

Return type mapping

The proxy determines the protocol message based on the method's return type:

Return type	Protocol	Behavior
void	SendMessage	Fire-and-forget (blocking)
Task	SendMessage	Fire-and-forget, awaitable
T (sync)	InvokeMessageResult	Invoke, blocks for result
Task<T>	InvokeMessageResult	Invoke, await result
IAsyncEnumerable<T>	StreamMessage	Server-to-client stream
IObservable<T>	StreamMessage	Server-to-client stream (Rx)
ChannelReader<T>	StreamMessage	Server-to-client stream (channel)

Generic method support

Proxies support generic method arguments. The type arguments are serialized as strings and resolved on the server:

[SignalARRRContract]
public interface IDataHub
{
    Task<T> GetItem<T>(string key);
}

var data = connection.GetTypedMethods<IDataHub>();
var user = await data.GetItem<User>("user-123");

Proxy caching

GetTypedMethods<T>() caches proxy instances. Calling it multiple times with the same type returns the same proxy object.

Source generator requirements

For proxy generation to work, the shared interface project must reference Cocoar.SignalARRR.Contracts:

<PackageReference Include="Cocoar.SignalARRR.Contracts" Version="4.*" />

The [SignalARRRContract] attribute triggers the Roslyn source generator, which produces a proxy class at build time. See Proxy Generation for details on how this works.

Next steps

• Server-to-Client Handlers — handle callbacks from the server
• Streaming — stream data from server methods
• Proxy Generation — how the source generator works