🎉 Online Auction System

Final Assignment – A robust, enterprise-grade Online Auction System built with Jakarta EE, packaged as an EAR, leveraging ActiveMQ for async messaging and tested using JMeter and VisualVM.

---

🏗️ Project Overview

This system enables users to list items for auction, place bids in real time, and receive notifications when auctions conclude. Key features:

• Modular Architecture: Core entities, EJB business logic, web APIs, and EAR packaging.
• Asynchronous Messaging: Notify winners and sellers via JMS queue (ActiveMQ).
• Performance Testing: Validate scalability with Apache JMeter and profile JVM with VisualVM.

---

📦 Architecture & Modules

The repository follows an Enterprise Archive (EAR) structure:

Online-Auction-System/
├── core/         # JAR: JPA entities (User, Item, Auction, Bid), DTOs, DAOs
├── ejb/          # EJB JAR: Stateless beans (AuctionServiceBean, BidServiceBean), JMS producers
├── web/          # WAR: JAX-RS REST endpoints under /api (UserResource, AuctionResource, BidResource)
├── ear/          # EAR: Aggregates core, ejb, web; contains application.xml & JMS resource descriptors
├── pom.xml       # Parent POM defining modules & dependency management
├── .gitignore
└── README.md     # This document

Core Module (core)

• Entities: User, Item, Auction, Bid with JPA annotations.
• DAOs: Generic CRUD operations via EntityManager.
• DTOs: Data transfer objects for REST payloads.

EJB Module (ejb)

• AuctionServiceBean (@Stateless): Create auctions, close auctions.

• BidServiceBean (@Stateless): Place bids with concurrency control.

• JMS Producer: Sends messages to notify users when auctions close.

  @Resource(lookup = "jms/AuctionConnectionFactory")
  private ConnectionFactory cf;
  @Resource(lookup = "jms/AuctionQueue")
  private Queue queue;
  
  public void notifyAuctionEnd(Auction auction) {
      try (JMSContext context = cf.createContext()) {
          context.createProducer()
                 .send(queue, auction.getId().toString());
      }
  }

Web Module (web)

• JAX-RS Resources:

  • UserResource for registration and login.
  • AuctionResource to list/create auctions.
  • BidResource to place bids (POST /api/auctions/{id}/bids).

• Security: Basic authentication (EJB interceptor or Jakarta Security).

EAR Module (ear)

• application.xml: Defines modules and context roots.

• JMS Resources: Included in META-INF for server configuration:

  <resource-ref>
    <res-ref-name>jms/AuctionQueue</res-ref-name>
    <res-type>javax.jms.Queue</res-type>
  </resource-ref>

---

🚦 ActiveMQ Integration

Apache ActiveMQ is our JMS broker for reliable, asynchronous messaging.

1. Setup Broker:

   brew install activemq            # MacOS, or download ZIP for Windows/Linux
   activemq start                   # Starts broker at tcp://localhost:61616

2. Define Resources in broker.xml:

   <queue physicalName="AuctionQueue" />

3. Producer Example: See ejb/src/main/java/.../AuctionServiceBean.java above.

4. Consumer Example: A separate EJB MDB listening on jms/AuctionQueue:

   @MessageDriven(activationConfig = {
     @ActivationConfigProperty(propertyName="destination", propertyValue="AuctionQueue"),
     @ActivationConfigProperty(propertyName="destinationType", propertyValue="javax.jms.Queue")
   })
   public class AuctionNotificationMDB implements MessageListener {
     public void onMessage(Message msg) {
       String auctionId = msg.getBody(String.class);
       // Lookup winning bid and email user...
     }
   }

---

🧪 Testing & Profiling

📊 Apache JMeter

Load-test REST endpoints to simulate high traffic:

1. Design Test Plan: Thread Group → HTTP Requests → Listeners.

2. Sample Command (Non-GUI):

   jmeter -n -t AuctionTest.jmx \
         -l AuctionResults.jtl -e -o AuctionReport

3. Key Metrics: Throughput, Response Time, Error Rate.

4. Importance: Validates scalability, identifies bottlenecks.

🖥️ VisualVM

Profile JVM performance in real time:

1. Launch VisualVM: bundled with JDK or standalone.
2. Attach to running App Server process.
3. Monitor: CPU, Heap, Threads, and perform Heap Dumps.
4. Profiler: Drill down into hot methods in EJBs and DAOs.
5. Importance: Detect memory leaks, thread contention, and heavy CPU usage.

---

🚀 Deployment & Quick Start

1. Build All Modules:

   mvn clean install

2. Deploy EAR:

   asadmin deploy ear/OnlineAuctionSystem.ear

3. Start ActiveMQ (see above).

4. Access API: http://localhost:8080/auction-web/api

---

---

📄 License & Contact

MIT © 2025 Tharindu714 Questions? Email: contact@example.com

---

Ready to bid? 🏷️ Happy coding and good luck on your final assignment!