Overview

The Notification Service is the central orchestrator for all notifications, handling creation, preference evaluation, batching, and routing to appropriate delivery channels.

Key Responsibilities

Notification Processing

• Listen to domain events (TaskAssigned, CommentAdded, etc.)
• Evaluate user notification preferences
• Determine notification priority and urgency
• Apply batching rules for digest notifications
• Route to appropriate delivery channels

Preference Management

• Store user notification preferences
• Handle muting and quiet hours
• Manage channel-specific settings
• Process unsubscribe requests

Delivery Orchestration

• Queue notifications for delivery
• Coordinate with Email and Push services
• Track delivery status
• Handle delivery failures and retries

Technical Details

Technology Stack:

• Runtime: Node.js 20
• Framework: NestJS
• Database: PostgreSQL (preferences, delivery log)
• Queue: AWS SQS (notification queue)
• Cache: Redis (user preferences)
• Message Broker: Apache Kafka

SLA:

• Availability: 99.95%
• Notification Latency: < 5 seconds for immediate
• Email Delivery: < 30 seconds
• Batch Processing: Every 15 minutes

Notification Rules Engine

• Rule-based evaluation of events
• User preference matching
• Intelligent batching algorithms
• Priority escalation logic

Integration Points

• Email Service: Send email notifications
• Push Service: Send mobile/web push
• Slack/Teams: External integrations
• Analytics: Track notification metrics