ReaperGT (@reaper_gt)

Don't blink.

Architecture

Component Index

1. Event Trigger & Dispatch

• 1. EventBridge – 1m
  Triggers a Lambda every minute to start the scraping cycle.

• 2. Lambda – Dispatcher
  Fetches all CRNs from DynamoDB and dispatches each one to the scrape queue.

2. Scraper Service

• 3. SQS – Scrape Queue
  Queue for CRNs to be scraped.

• 4. Lambda – Scraper
  Scrapes the course page for availability and forwards open CRNs to the notify queue.

3. Notification Service

• 5. SQS – Notify Queue
  Queue for open CRNs awaiting user notification.

• 6. Lambda – Notifier
  Looks up subscribers and sends alerts to the Telegram bot.

4. Console Service

• 7. Telegram
  Primary interface for users to subscribe, unsubscribe, or list CRNs.

• 8. REST API (API Gateway)
  Handles incoming webhook messages from Telegram.

• 9. Lambda – Console
  Parses commands and updates user/CRN data in DynamoDB.

5. Data Layer

• 10. Secrets Manager
  Stores secrets for the application.

• 11. DynamoDB – crns
  Stores course metadata and CRN subscription info.

• 12. DynamoDB – users
  Stores user info and the CRNs they are subscribed to.

Features

• Serverless architecture using AWS Lambda and SQS
• Real-time CRN alerts via Telegram
• Fully decoupled and scalable services
• Telegram command interface for user interaction
• Simple infrastructure with no Redis or EC2 instances

Example Commands

• /add 29333 – Subscribe to a CRN
• /rem 29333 – Unsubscribe
• /list – List currently subscribed CRNs

Deployment Notes

• Polling interval: 60 seconds via EventBridge
• Secrets and config stored in AWS Secrets Manager
• All services are stateless and scale independently

Future Improvements

• Add web interface for user management
• TTL support in DynamoDB to auto-clean expired CRNs
• Waitlist parsing and advanced notification rules