🗜️ Network File Compression System

IT432 – Network Programming | Assiut University
A multi-threaded TCP client-server system that compresses files over the network using GZip.

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📌 Overview

This project is a two-application system built in C# Windows Forms (.NET):

Application	Role
CompressionServer	Listens for clients, receives files, compresses them with GZip, sends them back
CompressionClient	Connects to the server, sends a file, receives the compressed result, saves it automatically

The server handles multiple clients simultaneously — each client connection runs on its own thread, so many clients can compress files at the same time without blocking each other.

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✨ Features

• ✅ Multi-threaded server — handles unlimited simultaneous clients
• ✅ Real-time client counter on the server GUI ("Clients Connected: N")
• ✅ Persistent TCP session — Connect once, send many files
• ✅ Heartbeat system — client detects if server goes down and shows a warning
• ✅ Session ID system — stopping and restarting the server kills ghost threads immediately
• ✅ GZip compression in-memory using System.IO.Compression.GZipStream
• ✅ Auto-save — compressed file saved as originalname.ext.gz next to the original
• ✅ Activity log on both server and client windows
• ✅ Clean WinForms GUI — drag-and-drop designer compatible

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🏗️ Project Structure

NetworkCompressionSystem/
├── CompressionServer/
│   └── CompressionServer/
│       └── Form1.cs          ← Server logic (all code here)
├── CompressionClient/
│   └── CompressionClient/
│       └── Form1.cs          ← Client logic (all code here)
└── README.md

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🚀 How to Run

Prerequisites

• Windows OS
• Visual Studio 2019 or later
• .NET Framework 4.7.2+ or .NET 6+

Step 1 — Open the Projects

Open two separate Visual Studio instances:

1. Open CompressionServer/CompressionServer.sln
2. Open CompressionClient/CompressionClient.sln

Or open both .csproj files inside one solution.

Step 2 — Build the GUI (Designer)

Each project needs its form controls added via the WinForms Designer.
See the Designer Reference section below for the exact control names.

Step 3 — Run

1. Start the server first → click Start Server
2. Start the client → enter the server IP → click Connect
3. Browse for any file → click Send File
4. The compressed .gz file is saved automatically next to the original

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🔌 Communication Protocol

CLIENT  ──── "CONNECT" (10 bytes) ────────────────►  SERVER
CLIENT  ◄─── "OK"      (2 bytes)  ────────────────   SERVER

CLIENT  ──── "PING"    (4 bytes)  ────────────────►  SERVER   (every 3 sec)
CLIENT  ◄─── "PONG"    (4 bytes)  ────────────────   SERVER

CLIENT  ──── "SEND"    (4 bytes)  ────────────────►  SERVER
CLIENT  ──── fileSize  (4 bytes)  ────────────────►  SERVER
CLIENT  ──── fileData  (N bytes)  ────────────────►  SERVER
CLIENT  ◄─── compSize  (4 bytes)  ────────────────   SERVER
CLIENT  ◄─── compData  (M bytes)  ────────────────   SERVER

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🧰 Designer Reference

Server — CompressionServer/Form1.cs

Control	Type	Name	Default Text
Server status	Label	lblStatus	"Stopped"
Client counter	Label	lblClients	"Clients Connected: 0"
Port input	TextBox	txtPort	"9050"
Start button	Button	btnStart	"Start Server"
Stop button	Button	btnStop	"Stop Server"
Activity log	ListBox	lstLog	(empty)

Event wiring: btnStart → btnStart_Click · btnStop → btnStop_Click

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Client — CompressionClient/Form1.cs

Control	Type	Name	Default Text
Server IP	TextBox	txtServerIP	"127.0.0.1"
Port	TextBox	txtPort	"9050"
Connect	Button	btnConnect	"Connect"
Disconnect	Button	btnDisconnect	"Disconnect"
File path	TextBox	txtFilePath	(ReadOnly)
Browse	Button	btnBrowse	"Browse File"
Send	Button	btnSend	"Send File"
Status	Label	lblStatus	"Not connected."
Original size	Label	lblOriginal	"Original size: —"
Compressed size	Label	lblCompressed	"Compressed size: —"
Activity log	ListBox	lstLog	(empty)

Event wiring: btnConnect → btnConnect_Click · btnDisconnect → btnDisconnect_Click · btnBrowse → btnBrowse_Click · btnSend → btnSend_Click

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🧪 Testing Multiple Clients

To test the multi-threading capability with 3 simultaneous clients:

1. Build the client project
2. Navigate to the output folder:

   CompressionClient\bin\Debug\net6.0-windows\
   

3. Double-click CompressionClient.exe three times → three separate windows open
4. Connect all three → send different files at the same time
5. Watch the server log show all three sessions running concurrently and the counter show Clients Connected: 3

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📚 Concepts Used

Concept	Where Used
TcpListener / TcpClient	Server accept loop & client connect
NetworkStream	All data transfer
Thread (one per client)	Server concurrency
GZipStream	In-memory file compression
Thread.IsBackground = true	Auto-cleanup on app exit
Control.Invoke()	Cross-thread UI updates in WinForms
Session ID pattern	Killing ghost threads on server restart
Heartbeat (PING/PONG)	Detecting server disconnection on client side

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📖 References

• Book: Hands-On Network Programming with C# and .NET Core (2019)
• Book: TCP/IP Sockets in C# – Practical Guide for Programmers
• Book: C# Network Programming – Richard Blum
• Course: IT432 – Network Programming, Assiut University

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👨‍💻 Author

[Khaled Ibrahim]
IT432 – Network Programming
Faculty of Computers and Information, Assiut University

Supervised by:
Dr. Ali Hussein Ahmed
IT432 – Network Programming
Faculty of Computers and Information, Assiut University

📄 License

This project is for educational purposes as part of the IT432 course at Assiut University.