Payamresan

A Distributed Java Socket-Based Messaging System

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📖 Introduction

Payamresan (Persian for "Messenger") is a robust, multi-component messaging application built entirely from scratch using Java Sockets.
It features a distributed architecture designed for scalability, separating coordination, execution, and user interaction into distinct, independent applications.

This project demonstrates core concepts of network programming, multithreading, and system design in Java, providing a practical example of how a distributed messaging service can be architected.

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✨ Features

• Distributed Architecture
  Composed of three independent applications:

  1. Central Server
  2. Host Server(s)
  3. Clients

• User Authentication
  Secure registration and login system.

• Dynamic Chat Rooms (Workspaces)
  Users can create isolated chat environments.

• Real-Time One-on-One Messaging
  Instant text communication inside workspaces.

• Chat History & Management

  • get-chats: View all conversations and unread counts.
  • get-messages: Retrieve full conversation history.

• Data Persistence
  JSON-based state saving for Central & Host Servers on shutdown, auto-loaded on startup.

• Command-Line Interface (CLI)
  User-friendly terminal-based interface.

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🏗️ System Architecture

The architecture is modular and scalable. Core components:

1️⃣ Central Server (The Brain)

• Runs on port 8000.
• Manages user registration, authentication, and workspace allocation.
• Registers Host Servers and assigns workspaces.
• Provides workspace connection details to clients.
• Does not handle chat messages directly.

2️⃣ Host Server (The Workhorse)

• Multiple instances can run on different machines.
• Registers itself with the Central Server (port range provided).
• Manages multiple isolated workspaces.
• Handles:
  • Message routing
  • Storage
  • History retrieval

3️⃣ Client (The User Interface)

• CLI app for user interaction.
• Communicates with Central Server for authentication & workspace info.
• Connects directly to Host Server for chat.
• Sends/receives real-time messages.
• Manages session state.

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🛠️ Tech Stack

• Language: Java (JDK 21)
• Build Tool: Apache Maven
• Networking: Java Sockets API
• Concurrency: Java Threads, ExecutorService
• Data Storage: JSON (Google Gson)
• Logging: SLF4J + Logback
• Boilerplate Reduction: Lombok

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🚀 How to Run

Prerequisites

• Java JDK 21+
• Apache Maven
• Git

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1. Clone the Repository

git clone https://github.com/your-username/payamresan-project.git
cd payamresan-project