How to implement sockets in C#

Socket is a type of communication channel to help different systems communicate with each other. Socket programming is a way of developing programs where systems can exchange messages through sockets. It is implemented in multiple languages, including C, Java, Ruby, and JavaScript etc. 

There are two sides to socket programming: client and server.

Server-side

Server is the system that fulfills the request of a client. It provides resources to the clients and ensures communication between multiple clients through sending and receiving messages.

We can implement a socket on a server using the following

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
Importing libraries

  • We import all the necessary namespaces.

public class Server
{
    public static void Main()
    {
Creating Server class with Main method

  • We create our Server class and declare a Main method in it that executes our code.

IPAddress serverAddress = IPAddress.Parse("12.0.0.7");
int serverPort = 8000;
Defining IP address and port number of our server

  • We store the IP address and port number used by our server.

Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
Creating socket

  • We create our socket using the socket class. The parameters in the class: AddressFamily.InterNetwork tells that our socket uses IPv4 address, SocketType.Stream and ProtocolType.cp tells that the connection type is TCP.

serverSocket.Bind(new IPEndPoint(serverAddress, serverPort));
Binding IP address and port number to the server

  • We connect our socket with the IP address and port of the server using the Bind function.

serverSocket.Listen(5);
Making server active and ready to listen

  • The Listen method makes the server active and ready to accept incoming client connections. The parameter in the function denotes the maximum number of pending connections that the serverSocket can line up before it starts rejecting new connections.

Socket clientSocket = serverSocket.Accept();
Accepting client's request

  • We call the function Accept to accept the incoming client connection. This function returns the connected shared socket between the client and the server stored in variable clientSocket.

byte[] temp = new byte[1024];
int clientBytes = clientSocket.Receive(temp);
string clientMessage = Encoding.ASCII.GetString(temp, 0, clientBytes);
Receiving message from client

  • We create a byte array temp to store bytes sent by the client. The function Receive receives a message sent by the client. The message received is in byte format so it is converted to a string and stored in variable clientMessage.

string serverMessage = "Hello, client!";
byte[] temp2 = Encoding.ASCII.GetBytes(serverMessage);
clientSocket.Send(temp2);
Sending message to client

  • The string serverMessage contains the message to be sent to the client by the server. It is converted to byte format and stored in byte array temp2. The Send function, sends the message to the client in the byte format.

clientSocket.Shutdown(SocketShutdown.Both);
clientSocket.Close();
serverSocket.Close();
Closing connection

  • In the last step, we use the Shutdown and Close method to discontinue the connection between the client and the server and then close the sockets of the client and server, respectively.

Client-side

The client sends the request to the server to use its services. After establishing a connection between the client and server, they can exchange messages and data.

We can implement a socket on the client-side using the following steps.

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
Importing libraries

  • We import all the necessary namespaces.

public class Client
{
    public static void Main()
    {
Creating client class and Main method

  • We create our Client class and declare a Main method in it that executes our code.

IPAddress serverAddress = IPAddress.Parse("12.0.0.7");
int serverPort = 8000;
Defining IP address and port number of the server

  • We store the IP address and port number used by our server. We will use this information to send a request to this specific server.

Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
Creating socket

  • We create our socket using the socket class. The parameters in the class: AddressFamily.InterNetwork tell that the socket uses IPv4 address, SocketType.Stream and ProtocolType.cp tells that the connection type is TCP.

clientSocket.Connect(new IPEndPoint(serverIP, serverPort));
Connecting client with IP address and port number of the server

  • We send a connection request to the server using the Connect function. We send the port number and IP address of the server as the parameter.

string clientMessage = "Hello, server!";
byte[] temp = Encoding.ASCII.GetBytes(clientMessage);
clientSocket.Send(temp);
Sending message to server

  • The string clientMessage contains the message we send to the server. It is converted to byte format and stored in the byte array temp. The function Send sends the message to the client in the byte format.

byte[] temp2 = new byte[1024];
int serverBytes = clientSocket.Receive(temp2);
string serverMessage = Encoding.ASCII.GetString(temp2, 0, serverBytes);
Receiving message from server

  • We create a byte array temp2 to store bytes sent by the server. We read the client's message using the Receive function. The message received is in byte format so it is converted to a string ans stored in variable serverMessage.

clientSocket.Shutdown(SocketShutdown.Both);
clientSocket.Close();
Closing connection

  • In the last step, we use the Shutdown and Close method to discontinue the connection between the client and the server and then close the client's socket respectively.

Implementation

The following code example shows the working of the client-server model we learned above in the Answer. 

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

public class Client
{
    public static void Main()
    {
        // Setting up the server IP address and port number
        IPAddress serverAddress = IPAddress.Parse("127.0.0.7");
        int serverPort = 8000;


         // Creating our client socket
        Socket clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

        // Connecting to the server
        clientSocket.Connect(new IPEndPoint(serverAddress,serverPort));
        Console.WriteLine("Connected to server!");

        // Sending message to the server
        string clientMessage = "Hello, server!";
        byte[] temp = Encoding.ASCII.GetBytes(clientMessage);
        clientSocket.Send(temp);

        // Receiving message from the server
        byte[] temp2 = new byte[1024];
        int serverBytes = clientSocket.Receive(temp2);
        string serverMessage = Encoding.ASCII.GetString(temp2, 0, serverBytes);
        Console.WriteLine("Received response from server: " + serverMessage);

        // Closing the connection
        clientSocket.Shutdown(SocketShutdown.Both);
        clientSocket.Close();
    }
}
Implementation of client server model in c#

Conclusion

Socket programming in C# allows the developers to communicate between different systems over a network. They can establish connections and exchange messages using the server and client side.

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