🚀 Distributed Online Auction System

Welcome to the Distributed Online Auction System repository!
This project is a robust, modular, and scalable platform for conducting real-time online auctions, built with modern Java EE technologies and a distributed architecture.
It is designed to deliver a seamless, interactive, and transparent auction experience for both administrators and bidders.

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📝 Overview

The Distributed Online Auction System (DOAS) provides a virtual marketplace where users can register, view auction items, place bids in real time, and compete to win products. The system leverages a distributed, multi-module architecture to ensure scalability, responsiveness, and maintainability.
Key features include:

• Real-time bidding with live updates via WebSockets
• Admin panel for managing auction items and monitoring bids
• Secure user sessions and authentication
• Auction timers and automatic auction closure
• Modular architecture for easy extension and maintenance

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📽️ Demo Video

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🗂️ Project Structure

The project is organized as a Maven multi-module application:

Distributed-Online-Auction-System/
├── core/
├── ejb/
├── web/
├── ear/
├── pom.xml

Module	Description
core	Domain models (AuctionItem, Bid, User) and shared logic
ejb	Enterprise JavaBeans (EJB) for business logic, bid processing, session management, and broadcasting
web	Web frontend, servlets, JSPs, WebSocket endpoints, and static resources
ear	Enterprise Archive for deployment, aggregating all modules

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🧩 Module Descriptions

1. core – Domain Model Layer

Defines the core business entities:

• AuctionItem: Represents an item available for auction, including name, description, starting price, and expiry time.
• Bid: Represents a bid placed by a user, including bidder details, bid amount, and the associated auction item.
• User: Represents a registered user (bidder), including name and email.

This module is shared by both EJB and web modules to ensure consistency across the application.[2]

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2. ejb – Business Logic Layer

Implements the core business processes using EJBs:

• AuctionManagerBean: Manages auction items and bids, provides methods to add items, retrieve items, and fetch bids.
• BidManagerBean: Handles bid validation and placement, ensuring that each bid is higher than the current highest and that the auction is active.
• BroadcasterBean: Sends bid updates to the messaging system (JMS), enabling real-time notifications.
• UserSessionManagerBean: Manages user sessions, mapping HTTP sessions to user objects for authentication and authorization.

Key Features:

• Thread-safe, singleton beans for shared state
• JMS integration for scalable, asynchronous bid broadcasting
• Robust exception handling for invalid bids[4]

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3. web – Presentation & Real-Time Layer

Provides the user interface and real-time communication:

• Servlets:
  • HomeServlet: Displays auction items and live bids to users
  • LoginServlet / LogoutServlet: User authentication and session management
  • AdminServlet / AdminLoginServlet: Admin authentication and item management
  • PlaceBidServlet: Handles bid submissions
• WebSocket:
  • BidWebSocketEndpoint: Enables real-time bid and item updates to all connected clients
  • WebSocketBroadcaster: Broadcasts messages to active WebSocket sessions
• JSP Pages:
  • index.jsp, login.jsp, auction.jsp, admin.jsp, etc., for user and admin interfaces
• Static Assets:
  • CSS, JS (including auction.js for client-side WebSocket logic), fonts, and images

User Experience:

• Live auction and bid updates without page reloads
• Countdown timers for auction expiry
• Responsive, Bootstrap-based UI[1]

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4. ear – Deployment Aggregator

Packages all modules into a single deployable EAR (Enterprise Archive):

• Bundles the core, ejb, and web modules
• Provides deployment descriptors and configuration for application servers (e.g., Payara, GlassFish)
• Ensures seamless integration and deployment of all components[3]

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📂 Detailed Project Structure

Distributed-Online-Auction-System/
├── core/
│   └── src/main/java/io/github/chamikathereal/auction/core/model/
│       ├── AuctionItem.java
│       ├── Bid.java
│       └── User.java
├── ejb/
│   └── src/main/java/io/github/chamikathereal/auction/ejb/
│       ├── bean/
│       ├── exception/
│       └── remote/
├── web/
│   └── src/main/java/io/github/chamikathereal/auction/web/
│       ├── listener/
│       ├── servlet/
│       └── websocket/
│   └── src/main/webapp/
│       ├── assets/
│       ├── *.jsp
├── ear/
│   └── src/main/
└── pom.xml

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🏛️ System Architecture

• Domain Layer (core): Defines entities and shared logic.
• Business Layer (ejb): Handles auction logic, bid processing, and session management.
• Presentation Layer (web): User/admin interfaces, real-time updates, and static content.
• Deployment Layer (ear): Aggregates and deploys all modules as a single application.

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🔍 Module Responsibilities

Module	Key Classes / Files	Responsibilities
core	AuctionItem, Bid, User	Domain models, serialization, and business rules
ejb	AuctionManagerBean, BidManagerBean, BroadcasterBean, UserSessionManagerBean, InvalidBidException	Business logic, bid validation, messaging, user session management
web	HomeServlet, LoginServlet, PlaceBidServlet, AdminServlet, BidWebSocketEndpoint, WebSocketBroadcaster, JSPs, JS/CSS	Web interface, real-time updates, REST endpoints, WebSocket communication, static resources
ear	application.xml, pom.xml	Deployment descriptor, module aggregation, application server integration

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⚙️ How It Works

1. Admin adds auction items via the admin panel.
2. Users register/login and view live auction items.
3. Users place bids; each bid is validated and processed by the EJB layer.
4. Bids are broadcasted in real time to all connected clients via JMS and WebSockets.
5. Auction timers control the start and end of each auction, automatically closing bidding when expired.
6. All activities are logged for transparency and debugging.

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🖥️ Technologies Used

• Java 11
• Jakarta EE (EJB, JMS, Servlet, WebSocket)
• JSP, HTML5, CSS3, Bootstrap 5
• JavaScript (for real-time updates)
• Maven (multi-module project)
• Payara/GlassFish (application server)

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📦 Getting Started

1. Clone the repository
   git clone https://github.com/chamikathereal/Distributed-Online-Auction-System.git

2. Build the project
   mvn clean install

3. Deploy the EAR file to your Java EE application server (e.g., Payara, GlassFish).

4. Access the application

   • User: http://localhost:8080/plexusbid/
   • Admin: http://localhost:8080/plexusbid/admin-login.jsp

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🏷️ Key Features

• Real-time, distributed auctioning
• Modular, maintainable codebase
• Secure session and bid management
• Responsive and modern UI
• Extensible for new auction types or features

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🧑‍💻 Author

Chamika Gayashan
Undergraduate Software Engineer | Sri Lanka
Linkedin: @chamikathereal

Current date: Wednesday, June 11, 2025, 8:45 PM +0530

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Thank you for checking out the Distributed Online Auction System! If you have any questions or suggestions, feel free to open an issue or reach out via LinkedIn.