SocketsHttpHandler.ConnectCallback Property

Definition

Namespace:

System.Net.Http

Assembly:

System.Net.Http.dll

Source:

SocketsHttpHandler.cs

Gets or sets a custom callback used to open new connections.

public:
 property Func<System::Net::Http::SocketsHttpConnectionContext ^, System::Threading::CancellationToken, System::Threading::Tasks::ValueTask<System::IO::Stream ^>> ^ ConnectCallback { Func<System::Net::Http::SocketsHttpConnectionContext ^, System::Threading::CancellationToken, System::Threading::Tasks::ValueTask<System::IO::Stream ^>> ^ get(); void set(Func<System::Net::Http::SocketsHttpConnectionContext ^, System::Threading::CancellationToken, System::Threading::Tasks::ValueTask<System::IO::Stream ^>> ^ value); };

public Func<System.Net.Http.SocketsHttpConnectionContext,System.Threading.CancellationToken,System.Threading.Tasks.ValueTask<System.IO.Stream>>? ConnectCallback { get; set; }

member this.ConnectCallback : Func<System.Net.Http.SocketsHttpConnectionContext, System.Threading.CancellationToken, System.Threading.Tasks.ValueTask<System.IO.Stream>> with get, set

Public Property ConnectCallback As Func(Of SocketsHttpConnectionContext, CancellationToken, ValueTask(Of Stream))

Property Value

Func<SocketsHttpConnectionContext,CancellationToken,ValueTask<Stream>>

A callback method to create a stream.

Exceptions

InvalidOperationException

An operation has already been started on the current instance.

ObjectDisposedException

The current instance has been disposed.

Examples

The following code example sets TCP KeepAlive on the underlying Socket.

static async Task Main()
{
    using SocketsHttpHandler handler = new SocketsHttpHandler();

    handler.ConnectCallback = async (ctx, ct) =>
    {
        DnsEndPoint dnsEndPoint = ctx.DnsEndPoint;
        IPAddress[] addresses = await Dns.GetHostAddressesAsync(dnsEndPoint.Host, dnsEndPoint.AddressFamily, ct);
        var s = new Socket(SocketType.Stream, ProtocolType.Tcp) { NoDelay = true };
        try
        {
            s.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.KeepAlive, true);
            s.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveTime, 5);
            s.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveInterval, 5);
            s.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.TcpKeepAliveRetryCount, 5);

            await s.ConnectAsync(addresses, dnsEndPoint.Port, ct);
            return new NetworkStream(s, ownsSocket: true);
        }
        catch
        {
            s.Dispose();
            throw;
        }
    };

    // Create an HttpClient object
    using HttpClient client = new HttpClient(handler);

    // Call asynchronous network methods in a try/catch block to handle exceptions
    try
    {
        HttpResponseMessage response = await client.GetAsync("https://learn.microsoft.com/");

        response.EnsureSuccessStatusCode();

        string responseBody = await response.Content.ReadAsStringAsync();
        Console.WriteLine($"Read {responseBody.Length} characters");
    }
    catch (HttpRequestException e)
    {
        Console.WriteLine("\nException Caught!");
        Console.WriteLine($"Message: {e.Message} ");
    }
}