chamikathereal / J2EE-Timer

A simple Java EE project demonstrating EJB Timer Service for scheduling and managing automated tasks. Ideal for learning timer-based automation in enterprise applications.

🚀 J2EE-Timer

📝 Project Overview

J2EE-Timer is a simple Java EE project that demonstrates how to schedule and manage timed tasks using EJB Timer Service. This project showcases both programmatic and automatic timer creation, making it a practical reference for understanding scheduled background processing in enterprise Java applications. The implementation covers stateless session beans, timer callbacks, and integration with servlets for task management—all following best practices for reliability and scalability.

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📽️ Demo Video

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🗂️ Project Structure

J2EE-Timer/
├── src/
│   └── main/
│       ├── java/
│       │   └── lk.jlat.web.eetimer/
│       │       ├── ejb/
│       │       │   ├── remote/
│       │       │   ├── AutoTimerSessionBean
│       │       │   ├── TaskSessionBean
│       │       │   └── TimerSessionBean
│       │       ├── servlet/
│       │       │   ├── Task2
│       │       │   └── Test
│       │       └── timer/
│       │           └── Task
│       ├── resources/
│       └── webapp/
│           └── index.jsp
├── pom.xml

Modules & Key Files

🟦 ejb

• AutoTimerSessionBean
  Handles automatic scheduling using @Schedule annotation for recurring tasks.

• TaskSessionBean
  Demonstrates asynchronous task execution using a managed executor service.

• TimerSessionBean
  Manages programmatic timers, calendar-based scheduling, timer callbacks (@Timeout), and timer cancellation.

🟦 servlet

• Test
  Servlet to trigger and schedule a new timer task via TimerSessionBean.

• Task2
  Servlet to cancel an existing timer by referencing the scheduled task.

🟦 timer

• Task
  Serializable class representing a scheduled task's identity and metadata.

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⚙️ How It Works

• ✅ Automatic Timers:
  Use @Schedule in AutoTimerSessionBean to run methods at fixed intervals without manual intervention.

• ✅ Programmatic Timers:
  TimerSessionBean creates timers dynamically using TimerService, schedules tasks, and handles timeout events with @Timeout methods.

• ✅ Task Execution:
  TaskSessionBean leverages Java EE's managed executor service for asynchronous operations.

• ✅ Servlet Integration:
  The Test servlet triggers new timers and stores task info in the session, while Task2 cancels the timer based on task ID.

• ✅ Persistence & Configuration:
  Maven-based project setup with Java 11 and Jakarta EE 10 dependencies for modern, portable deployment.

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✨ Key Features

• ✅ Demonstrates both annotation-based and programmatic EJB timers
• ✅ Showcases timer callbacks and cancellation
• ✅ Integrates servlets for web-based task management
• ✅ Clean, modular code for easy learning and extension

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🛠️ Technologies Used

• Java 11
• Jakarta EE 10 (EJB, Servlet)
• Maven

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📚 Learning Outcomes

• ✅ Understand EJB Timer Service for scheduled and recurring tasks
• ✅ Learn to implement both automatic and programmatic timers
• ✅ Explore asynchronous processing in Java EE
• ✅ Gain hands-on experience with modular enterprise Java applications

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🧑‍💻 Author

Chamika Gayashan
Undergraduate Software Engineer | Sri Lanka
Linkedin: @chamikathereal
Current date: Saturday, June 21, 2025, 11:47 PM +0530