.NET Documentation – Networking

Overview

The .NET networking stack provides a rich set of APIs for building reliable, high‑performance networked applications. From low‑level socket programming to high‑level HTTP clients, .NET abstracts the complexities of the underlying protocols.

Key Namespaces

• System.Net – Core networking types such as WebClient, WebRequest, and Dns.
• System.Net.Sockets – Low‑level socket APIs for TCP/UDP.
• System.Net.Http – Modern HTTP client and server abstractions.
• System.Net.WebSockets – Full‑duplex communication over WebSockets.

Example: Simple TCP Client

using System;
using System.Net.Sockets;
using System.Text;

class TcpEchoClient
{
    static async Task Main()
    {
        using var client = new TcpClient();
        await client.ConnectAsync("localhost", 5000);
        NetworkStream stream = client.GetStream();

        string message = "Hello, server!";
        byte[] data = Encoding.UTF8.GetBytes(message);
        await stream.WriteAsync(data, 0, data.Length);

        var buffer = new byte[1024];
        int bytesRead = await stream.ReadAsync(buffer, 0, buffer.Length);
        string response = Encoding.UTF8.GetString(buffer, 0, bytesRead);
        Console.WriteLine($"Received: {response}");
    }
}
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Example: HTTP GET with HttpClient

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        using var http = new HttpClient();
        HttpResponseMessage resp = await http.GetAsync("https://api.github.com/repos/dotnet/runtime");
        resp.EnsureSuccessStatusCode();
        string json = await resp.Content.ReadAsStringAsync();
        Console.WriteLine(json);
    }
}
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Best Practices

• Prefer HttpClient over older WebRequest APIs.
• Reuse HttpClient instances to avoid socket exhaustion.
• Use async APIs to keep applications responsive.
• Validate certificates when using TLS.
• Handle transient failures with retry policies (e.g., Polly library).