TCP .NET（開發者使用指南）

1. 可靠性

序號、確認和重傳只是 TCP 用於保證可靠資料傳輸的幾種技術。 發送方發送資料包，然後等待接收方確認資料包已成功送達。 為確保資料包成功送達，如果在預定時間內未收到確認訊息，發送者會重新發送該資料包。這種可靠性機制有助於避免傳輸過程中出現資料遺失或損壞。

2. 以連結為導向的溝通

在發送資料之前，TCP協定會在發送方和接收方之間建立連線。 為了建立同步並確定通訊設置，發送方和接收方在連線建立過程中會進行三次握手。資料可以在雙方之間來回傳輸，直到連線斷開為止。

3. 流量管理

為了控制資料從發送方發送到接收方的速度，TCP 使用流量控制方法。 流量控制採用滑動視窗方法來防止發送方向接收方發送過多資料。 發送方可以透過回應接收方對其可用緩衝區空間的通告來修改其傳輸速率。 這樣做可以有效利用網路資源，避免網路擁塞或緩衝區溢位。

TCP 程式碼分為兩部分：一部分是伺服器端，另一部分是客戶端。 伺服器代碼使用 IP 位址和連接埠向客戶端發送訊息，客戶端接收資料並進行相應處理。

TCP伺服器程式碼

// 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();
    }
}

在本伺服器程式碼中，我們將建立一個 TCP 伺服器程式碼，該程式碼會將資料包傳送到已連線的用戶端。 伺服器接受傳入的連接，並透過 TCP 套接字發送訊息。

TCP客戶端程式碼

// 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();
    }
}

上述客戶端程式碼連接到 TCP 套接字並讀取從 TCP 伺服器接收的字串訊息，然後將該訊息顯示在控制台上。 本範例示範了 .NET 環境中基本的 TCP 用戶端-伺服器通訊。

TCP .NET（開發者使用指南）：圖 3