Notifications Engine

Relevant source files

The following files were used as context for generating this wiki page:

• src/main/java/com/example/demo/controllers/NotificationController.java
• src/main/java/com/example/demo/services/NotificationService.java
• src/main/java/com/example/demo/entity/Notification.java
• src/main/java/com/example/demo/services/CommentService.java
• src/main/resources/static/js/api.js
• src/main/resources/templates/projects.html
• src/main/resources/static/js/projects.js

The Notifications Engine is a core service within the Dashboard Task Management (DTM) project designed to alert users about critical task-related events. It facilitates real-time-like communication by tracking events such as task assignments, status changes, new comments, user mentions, and overdue deadlines.

The system encompasses a backend architecture built on Spring Boot for persistence and business logic, and a frontend integration using Thymeleaf and JavaScript to display alerts and manage user interactions with notifications.

Architecture and Data Flow

The engine follows a standard service-oriented architecture. Events triggered in other modules (like CommentService) call the NotificationService to persist alerts in a PostgreSQL database. Users then retrieve these notifications via a REST API.

Logic Flow for Notification Creation

When a significant event occurs (e.g., a new comment is added), the system identifies the relevant participants and creates notification records for each.

Data Model

The Notification entity stores the state of an alert, linking it to a specific user and, optionally, a specific task.

Field	Type	Description
id	Long	Primary key
user	User	Recipient of the notification
type	String	Categories: TASK_ASSIGNED, STATUS_CHANGED, NEW_COMMENT, MENTION, TASK_OVERDUE
task	Task	Optional link to the relevant task
message	String	Descriptive text of the notification
isRead	boolean	Read status (default: false)
createdAt	LocalDateTime	Timestamp of creation

Sources: src/main/java/com/example/demo/entity/Notification.java:13-39, README.md:144-150

Backend Components

NotificationService

The service layer manages the business logic for creating, retrieving, and marking notifications as read.

• notifyTaskParticipants: Sends notifications to the task creator and all assignees, excluding the user who performed the action.
• markTaskNotificationsAsRead: Automatically clears notifications for a specific task when a user opens that task's detail page.
• wasOverdueNotificationSentToday: A check used by schedulers to prevent duplicate overdue alerts within the same day.

Sources: src/main/java/com/example/demo/services/NotificationService.java:33-100

NotificationController (REST API)

Exposes endpoints for the frontend to interact with the notifications.

Method	Endpoint	Description
GET	/api/notifications	Retrieves all notifications for the current user
GET	/api/notifications/unread	Retrieves only unread notifications
GET	/api/notifications/count	Returns a count of unread notifications for the UI badge
PATCH	/api/notifications/{id}/read	Marks a specific notification as read
PATCH	/api/notifications/read-all	Marks all user notifications as read
DELETE	/api/notifications/{id}	Deletes a notification (ADMIN only)

Sources: src/main/java/com/example/demo/controllers/NotificationController.java:25-65

Frontend Integration

The user interface features a "bell" icon in the navbar that displays an unread count badge. Clicking this icon opens a dropdown list of recent alerts.

Sequence: Loading and Viewing Notifications

The following sequence illustrates how the frontend retrieves and displays notifications.

Implementation Detail: The Notif-Badge

The unread count is injected via Thymeleaf and managed dynamically via JavaScript:

<button class="notif-btn" onclick="toggleNotif()" title="Уведомления">
    🔔
    <span class="notif-badge" th:text="${unreadCount}"
          th:style="${unreadCount == 0} ? 'display:none' : ''">0</span>
</button>

Sources: src/main/resources/templates/projects.html:21-24

Summary

The Notifications Engine provides an automated way to keep users informed of project activity. By integrating deeply with the CommentService and task status updates, it ensures that participants are notified of changes in real-time. The system supports administrative cleanup and provides a streamlined user experience through automatic "read" marking and centralized notification management.