C# — Transport

Transport types are in the Nnrp.Transport namespace. The current stable implementation provides TCP framed transport; QUIC support is planned for Preview3.

Import

using Nnrp.Transport;
using Nnrp.Core;

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Transport Interfaces

INnrpMessageTransport

Unified transport interface for both client and server.

public interface INnrpMessageTransport : IAsyncDisposable
{
    TransportId TransportId { get; }
    bool IsConnected { get; }
    Task<NnrpFramedMessage> ReceiveAsync(CancellationToken ct = default);
    Task SendAsync(NnrpFramedMessage message, CancellationToken ct = default);
    Task CloseAsync(CancellationToken ct = default);
}

INnrpMessageSender

Write-only view of a transport (for sending only).

public interface INnrpMessageSender
{
    Task SendAsync(NnrpFramedMessage message, CancellationToken ct = default);
}

INnrpMessageReceiver

Read-only view of a transport (for receiving only).

public interface INnrpMessageReceiver
{
    Task<NnrpFramedMessage> ReceiveAsync(CancellationToken ct = default);
}

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TCP Transport

NnrpTcpMessageTransport implements INnrpMessageTransport over a System.Net.Sockets.TcpClient or TcpListener. Uses length-prefixed framing (4-byte big-endian frame length prefix).

Bind Server

public static Task<NnrpTcpMessageTransport> BindServerAsync(
    string host,
    int port,
    NnrpTcpServerOptions? options = null,
    CancellationToken ct = default);

Connect Client

public static Task<NnrpTcpMessageTransport> ConnectClientAsync(
    string host,
    int port,
    NnrpTcpClientOptions? options = null,
    CancellationToken ct = default);

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TCP Configuration

NnrpTcpClientOptions

Property	Type	Default	Description
ConnectTimeoutMs	int	10000	Connection timeout (ms)
IdleTimeoutMs	int	30000	Idle timeout (ms)
MaxFrameBytes	int	33554432	Max frame size (32 MB)
SendBufferSize	int	65536	TCP send buffer size
ReceiveBufferSize	int	65536	TCP receive buffer size

NnrpTcpServerOptions

Property	Type	Default	Description
IdleTimeoutMs	int	30000	Idle timeout (ms)
MaxFrameBytes	int	33554432	Max frame size (32 MB)
SendBufferSize	int	65536	TCP send buffer size
ReceiveBufferSize	int	65536	TCP receive buffer size
Backlog	int	128	Connection backlog

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QUIC Transport (Preview3)

Note: QUIC transport support is planned for Preview3. The interface will match INnrpMessageTransport exactly; existing code will require only a transport factory change.

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Custom Transport

Implement INnrpMessageTransport to plug in any custom transport layer:

public class MyCustomTransport : INnrpMessageTransport
{
    public TransportId TransportId => TransportId.Unspecified;
    public bool IsConnected { get; private set; }

    public async Task<NnrpFramedMessage> ReceiveAsync(CancellationToken ct)
    {
        // Your receive logic here
    }

    public async Task SendAsync(NnrpFramedMessage message, CancellationToken ct)
    {
        // Your send logic here
    }

    public Task CloseAsync(CancellationToken ct)
    {
        IsConnected = false;
        return Task.CompletedTask;
    }

    public ValueTask DisposeAsync()
    {
        // Cleanup
        return ValueTask.CompletedTask;
    }
}

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Typical Use Cases

QUIC Client

var quicConfig = new NnrpQuicClientConfiguration
{
    CertificateAuthority = X509Certificate2.CreateFromPemFile("ca.pem"),
    IdleTimeout          = TimeSpan.FromSeconds(30),
};
var transport = new NnrpQuicTransport(quicConfig);
await using var client = await NnrpClient.ConnectAsync(host, port, profile,
                                                         transport: transport);

TCP Fallback

var tcpConfig = new NnrpTcpClientConfiguration
{
    ConnectTimeout = TimeSpan.FromSeconds(5),
    IdleTimeout    = TimeSpan.FromSeconds(60),
};
var transport = new NnrpTcpTransport(tcpConfig);

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Common Pitfalls

WARNING

1. QUIC requires the correct ALPN. Use NnrpQuicClientConfiguration.DefaultAlpn; do not hardcode the string.

2. SkipCertificateValidation = true is for local dev only. CI/staging must use a CA certificate.

3. TCP does not support Datagram operations (e.g., transport probes). These throw NnrpUnsupportedOperationException.

4. await using var transport — NnrpQuicTransport / NnrpTcpTransport implement IAsyncDisposable. Forgetting to dispose leaks the underlying socket.