System.Net.Sockets Namespace

Provides low-level classes for network communication using sockets. This namespace contains classes that enable you to send and receive data across networks using various protocols, including TCP and UDP.

Key Classes

`Socket` Class

The Socket class provides the fundamental functionality for sending and receiving data using the socket API. It allows for flexible network programming, supporting both connection-oriented (like TCP) and connectionless (like UDP) protocols.

Properties

Name	Description
`Available`	Gets the number of bytes of data available to be read from the network buffer.
`Blocking`	Gets or sets a value indicating whether the `Socket` is in blocking mode.
`Connected`	Gets a value indicating whether the `Socket` is connected to a remote host.
`Handle`	Gets the native socket handle.
`IsBound`	Gets a value indicating whether the `Socket` is bound to a local endpoint.
`LocalEndPoint`	Gets the local endpoint to which the `Socket` is bound.
`ProtocolType`	Gets the protocol type of the `Socket`.

Methods

Name	Description
`Bind(EndPoint localEP)`	Binds the `Socket` to a local endpoint.
`Connect(EndPoint remoteEP)`	Establishes a connection to a remote host.
`Listen(int backlog)`	Puts a listening `Socket` into a listening state.
`Accept()`	Accepts an incoming connection attempt and creates a new `Socket` to handle remote host communication.
`Send(byte[] buffer)`	Sends the entire buffer containing data to the remote host.
`Receive(byte[] buffer)`	Receives data from the network into the specified buffer.
`Close()`	Releases all resources used by the `Socket`.

Note: The Socket class is powerful but can be complex to use directly. For many common networking scenarios, higher-level classes like TcpClient and UdpClient offer a simpler abstraction.

`TcpClient` Class

Provides a client side of a TCP service. This class simplifies the implementation of network-aware applications by providing a managed wrapper around the Socket class for TCP connections.

Establishes TCP connections to remote hosts.
Provides access to the underlying Socket for advanced control.
Offers GetStream() to get a NetworkStream for sending and receiving data.

`UdpClient` Class

Provides support for User Datagram Protocol (UDP) network services. This class simplifies sending and receiving UDP datagrams.

Sends and receives UDP datagrams.
Does not require a connection to be established before sending data.
Useful for broadcasting or sending small amounts of data where reliability is not critical.

Common Use Cases

Server Development: Implementing listening sockets to accept incoming connections.
Client Development: Creating sockets to connect to remote servers.
Data Transfer: Sending and receiving raw byte data over the network.
Low-Level Network Programming: When fine-grained control over network packets and protocols is required.

Example: Simple TCP Echo Client

This example demonstrates a basic TCP client that connects to a server and sends a message, then receives the echoed response.


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

public class SimpleTcpClient
{
    public static void Main(string[] args)
    {
        string serverIp = "127.0.0.1"; // Replace with your server's IP
        int port = 8080; // Replace with your server's port
        string messageToSend = "Hello, Server!";

        try
        {
            using (TcpClient client = new TcpClient(serverIp, port))
            {
                Console.WriteLine($"Connected to {serverIp}:{port}");

                NetworkStream stream = client.GetStream();

                // Send message
                byte[] dataToSend = Encoding.ASCII.GetBytes(messageToSend);
                stream.Write(dataToSend, 0, dataToSend.Length);
                Console.WriteLine($"Sent: {messageToSend}");

                // Receive response
                byte[] buffer = new byte[1024];
                int bytesRead = stream.Read(buffer, 0, buffer.Length);
                string responseData = Encoding.ASCII.GetString(buffer, 0, bytesRead);
                Console.WriteLine($"Received: {responseData}");
            }
        }
        catch (Exception e)
        {
            Console.WriteLine($"Error: {e.Message}");
        }
        Console.WriteLine("Press Enter to exit.");
        Console.ReadLine();
    }
}

Tip: Always wrap network operations in try-catch blocks to handle potential network errors, connection issues, or timeouts gracefully.

.NET Documentation

System.Net.Sockets Namespace

Key Classes

Socket Class

Properties

Methods

TcpClient Class

UdpClient Class

Common Use Cases

Example: Simple TCP Echo Client

`Socket` Class

`TcpClient` Class

`UdpClient` Class