TCP .NET（對於開發者的運行原理）

1. 可靠性

TCP 使用序列號、確認和重傳等技術來保證可靠的數據傳送。 發送者發送數據包，然後等待接收者確認數據包已成功傳送。 如果在預定時間內未收到確認，則發送方將重新傳送數據包。這種可靠性機制有助於避免傳輸時數據遺失或損壞。

2. 面向連線通訊

在發送數據之前，TCP 協定會在發送方和接收方之間建立連接。 為了建立同步和決定通信設定，發送方和接收方在連接設置期間進行了三次握手過程。數據可以在雙方之間來回傳送，直到連接被斷開。

3. 流量管理

TCP 使用流量控制方法來管理從發送方到接收方的數據傳送速度。 流量控制使用滑動窗口方法來阻止發送方向接收方發送過多的數據。 發送者可以藉由回應接收者廣告的可用緩衝區大小來調整其傳輸速度。 通過這種方式，可以有效使用網路資源，並避免擁塞或緩衝區溢出。

TCP 代碼分為兩部分：一部分是伺服器，另一部分是客戶端。 伺服器代碼使用 IP 位址和埠發送訊息給客戶端，客戶端接收資料並相應處理。

TCP 伺服器代碼

// Basic TCP Server Code in C#
using System;
using System.Net;
using System.Net.Sockets;
using System.IO;

class TcpServer
{
    static void Main()
    {
        // Set up the server endpoint with localhost IP address and a specified port
        var endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 57472);

        // Create a new TcpListener and start listening for incoming connections
        TcpListener listener = new TcpListener(endPoint);
        listener.Start();
        Console.WriteLine("Server listening...");

        // Accept a TcpClient once a connection attempt is made
        TcpClient client = listener.AcceptTcpClient();
        Console.WriteLine("Client connected");

        // Obtain a NetworkStream object for reading and writing data
        NetworkStream stream = client.GetStream();
        StreamWriter writer = new StreamWriter(stream);

        // Write a message to the client's stream and flush to ensure it's sent
        writer.WriteLine("Hello from the server");
        writer.Flush();

        Console.WriteLine("Message sent from server");
        // Close the client connection
        client.Close();

        // Stop the server listener after communication
        listener.Stop();
    }
}

// Basic TCP Server Code in C#
using System;
using System.Net;
using System.Net.Sockets;
using System.IO;

class TcpServer
{
    static void Main()
    {
        // Set up the server endpoint with localhost IP address and a specified port
        var endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 57472);

        // Create a new TcpListener and start listening for incoming connections
        TcpListener listener = new TcpListener(endPoint);
        listener.Start();
        Console.WriteLine("Server listening...");

        // Accept a TcpClient once a connection attempt is made
        TcpClient client = listener.AcceptTcpClient();
        Console.WriteLine("Client connected");

        // Obtain a NetworkStream object for reading and writing data
        NetworkStream stream = client.GetStream();
        StreamWriter writer = new StreamWriter(stream);

        // Write a message to the client's stream and flush to ensure it's sent
        writer.WriteLine("Hello from the server");
        writer.Flush();

        Console.WriteLine("Message sent from server");
        // Close the client connection
        client.Close();

        // Stop the server listener after communication
        listener.Stop();
    }
}

在此伺服器代碼中，我們正在創建一個將資料包發送到連接的客戶端的 TCP 伺服器代碼。 伺服器接受來自 TCP 套接字的傳入連接並發送訊息。

TCP 客戶端代碼

// TCP client code
using System;
using System.Net;
using System.Net.Sockets;
using System.IO;

class TcpClientExample
{
    static void Main()
    {
        // Set up the client to connect to the same endpoint as the server
        var endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 57472);

        // Initialize a new TcpClient and connect to the server endpoint
        TcpClient client = new TcpClient();
        client.Connect(endPoint);

        // Use a NetworkStream to read data received from the server
        NetworkStream stream = client.GetStream();
        StreamReader reader = new StreamReader(stream);

        // Read the response sent by the server and display it
        string response = reader.ReadLine();
        Console.WriteLine($"Message from server: {response}");

        // Close the connection once done
        client.Close();
    }
}

// TCP client code
using System;
using System.Net;
using System.Net.Sockets;
using System.IO;

class TcpClientExample
{
    static void Main()
    {
        // Set up the client to connect to the same endpoint as the server
        var endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 57472);

        // Initialize a new TcpClient and connect to the server endpoint
        TcpClient client = new TcpClient();
        client.Connect(endPoint);

        // Use a NetworkStream to read data received from the server
        NetworkStream stream = client.GetStream();
        StreamReader reader = new StreamReader(stream);

        // Read the response sent by the server and display it
        string response = reader.ReadLine();
        Console.WriteLine($"Message from server: {response}");

        // Close the connection once done
        client.Close();
    }
}

在上述客戶端代碼中，連接到 TCP 套接字並讀取從 TCP 伺服器接收到的字串訊息，然後它在主控台上顯示訊息。 此範例說明了在 .NET 環境下基本的 TCP 客戶端伺服器通信。