Notification System

Goal

• User should be able to receive notification

Functional Requirement

• Should support multi channel delivery

• Should support personalization

• Should respect user preference

• Should have delivery guarantees

• Retry on delivery failure

Non Functional Requirement

• CAP

  • Availablilty and Partition Tolerance

• Scalability

  • Should scale upto 1 million notification/minute

    • Should have 70(critical)-30(promo) split.

• Fault Tolerance

  • Retry on failure, to ensure atleast once delivery semantics

• Durability

  • Notification delivery Logs

  • User preference

• Latency

  • Urgent Notificaiton : 1-5s

  • Standard Notification: 10 - 15s

  • Promotional Notification: upto 20-30s

• Security

  • In transit encryption data when sending from Notification Service to App via Providers.

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• Regional Compliance

• Observability

Core Entities

• Client

• User Preference

• Notification

• Template

API Interface

• Send Notification //No SQL

  POST /notification
  {
      "notificationId" : "",
      "userId" : "1234",
      "templateId" : "1234",
      "body": "<Noitification>" //json
      "channels" : ["EMAIL", "PUSH"],
      "key": "<idempotency>",
      "status": "PENDING/INPROGRESS/NOTIFIED",
      "priority": "HIGH/MEDIUM/LOW",
      "from": "Client Name",
      "creationTimeStamp": "",
  }

• Template //NoSQL

  {
      "templateId": "",
      "content": ""
  }

• User Preference // Nosql

  {
      "userPrefId": "",
      "userId": "",
      "emailPref": enabled/disable <boolean>,
      "smsPref": enabled/disable <boolean>,
      "appPref": enabled/disable <boolean>
  }