Socket Communication Project

Overview

This project demonstrates inter-process communication using network sockets in .NET. It consists of a socket server and client application that communicate over TCP/IP, implementing core socket programming concepts.

Project Structure

├── SocketServer/
│   └── Program.cs    // Server implementation
└── SocketClient/
    └── Program.cs    // Client implementation

Features

• TCP/IP socket communication
• Client-server architecture
• Bi-directional message exchange
• Multi-client support with threaded connections
• Connection management and cleanup

Technologies

• .NET Core/6.0+
• System.Net.Sockets namespace
• TCP/IP networking

Socket Implementation Comparison: .NET vs C

Feature	.NET Implementation	C Implementation
Socket Creation	new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)	socket(AF_INET, SOCK_STREAM, 0)
Binding	socket.Bind(ipEndPoint)	bind(sockfd, (struct sockaddr*)&address, sizeof(address))
Listening	socket.Listen(backlog)	listen(sockfd, backlog)
Connection	socket.Connect(endPoint)	connect(sockfd, (struct sockaddr*)&address, sizeof(address))
Accepting	Socket client = serverSocket.Accept()	clientfd = accept(sockfd, (struct sockaddr*)&client_addr, &addr_len)
Sending	socket.Send(buffer)	send(sockfd, buffer, length, flags)
Receiving	socket.Receive(buffer)	recv(sockfd, buffer, length, flags)
Threading	Task or Thread	pthread_create()
Error Handling	Exceptions	Error codes and errno
Address Structure	IPEndPoint	struct sockaddr_in
Memory Management	Automatic	Manual

Key Concepts Learned

• Socket lifecycle (create, bind, listen, accept, receive/send, close)
• Difference between Unix domain sockets and internetwork sockets
• Port usage and management (server fixed ports vs client ephemeral ports)
• TCP connection identification via 4-tuple (source IP, source port, destination IP, destination port)
• Resource limitations in socket connections
• Thread management for multiple client connections

Running the Project

Server

cd SocketServer
dotnet run

Client

cd SocketClient
dotnet run

Understanding Sockets: Unix vs TCP

What Are Sockets?

Sockets are communication endpoints that enable processes to exchange data, whether on the same machine or across a network. They provide a standardized API for network and inter-process communication in operating systems.

How Sockets Work

Sockets follow a client-server model where:

1. A server creates a socket, binds it to an address, and listens for connections
2. A client creates a socket and connects to the server's address
3. Once connected, both sides can send and receive data bidirectionally
4. When communication is complete, either side can close the connection

Socket Types Comparison

Feature	Unix Domain Sockets	TCP/IP Sockets
Communication Scope	Same machine only	Local or across networks
Addressing Mechanism	File system paths	IP address + port number
Address Format	/path/to/socket	192.168.1.100:8080
Performance	Higher (avoids network stack)	Lower (requires protocol overhead)
Address Family	AF_UNIX / AddressFamily.Unix	AF_INET / AddressFamily.InterNetwork
Connection Identification	File descriptor	4-tuple (source IP, source port, destination IP, destination port)
Security	File system permissions	Network-level security
Use Cases	Fast IPC between local processes	Communication between processes on different machines
Port Usage	No concept of ports	Requires port allocation
Durability	Socket file remains until explicitly removed	Terminates when process ends

Key Distinctions

Unix Domain Sockets

• Use file paths as addresses
• Don't require network protocol overhead
• Provide higher performance for local communication
• Limited to processes on the same machine
• File permissions control access

TCP/IP Sockets

• Use IP addresses and ports
• Work across network boundaries
• Client connections use ephemeral ports assigned by OS
• Support thousands of concurrent connections via unique 4-tuple identifiers
• Require more system resources and overhead

Common Applications

• Unix Sockets: Database engines (PostgreSQL, MySQL), X Window System, Container communications
• TCP Sockets: Web servers/browsers, email clients/servers, remote login, file transfers

Both socket types follow similar programming patterns but differ in how they're addressed and the scope of their communication capabilities.

Future Enhancements

• Implement asynchronous socket operations
• Add protocol definition for structured messages
• Improve error handling and recovery
• Implement connection pooling
• Add configuration options for IP/port
• Create performance benchmarks

Resources

• Microsoft Docs: Socket Class
• TCP/IP Network Programming in C#
• .NET Socket Programming Guide

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This project was created as a learning exercise to understand socket communication in .NET.