Notification Application

• Send Reddit Notification Email

Start application

• run the docker-compose available in the root directory.
• To start run below command

docker-compose up -d

• To Stop run below

docker-compose down

• Either you can remove the volume path from docker-compose but data will be lost if container is stopped, Or change it to your local path.

• Create Sendgrid Api key and set it in the Application.yml

    api:
      key: {Please add your Sendgrid API key}

• Then run the application directly from your id. Application starts at 8081 port.

High Level Design of Application

User recieve below Email

Resources

******** User API ********

• Create User Account
• URL

http://localhost:8081/api/user/create/

• PUTRequest

{
	"fullName":"Umesh Verma",
	"emailId":"TestEmail@gmail.com",
	"countryCode": "DE",
	"notificationStatus": "SUBSCRIBED"
}

Add User profile

• GETRequest with Path Param {emailId}
• URL

http://localhost:8081/api/user/fetch/{emailId}

• Response Format : Please Note UserId is essential for further API call

{
    "userId": "dd178821-15c6-45c2-9b97-7df4d1ce73d1",
    "emailId": "TestEmail@gmail.com",
    "notificationStatus": "SUBSCRIBED"
}

Enable Subscription for USER by default it is enabled

• URL

http://localhost:8081/api/user/enableSubscription

• PUTRequest

{ 
    "userId": "8b065a35-b305-49e9-b601-2e7ecbe84f4f"
}

Disable Subscription for USER

• URL

http://localhost:8081/api/user/disableSubscription

• PUTRequest

{ 
    "userId": "8b065a35-b305-49e9-b601-2e7ecbe84f4f"
}

******** Subscription API for USER: ********

Add channels. By default, notification is enabled for USERS. Use user API to disable.

• URL

http://localhost:8081/api/subscribe/addChannel

• PUTRequest

{
    "userId": "dd178821-15c6-45c2-9b97-7df4d1ce73d1",
    "redditChannel": "technology"
}

Update user channel:

• This API removes all the old subscribed channels and Add new updated channel.

• URL

http://localhost:8081/api/subscribe/updateChannel

• PUTRequest

{
    "userId": "dd178821-15c6-45c2-9b97-7df4d1ce73d1",
    "redditChannel": "technology"
}

******** Email Notification ********

send Email notification to user at any time.

• This API will send the email to list of user provided they have notification enabled and have valid channel subscribed.

• URL

http://localhost:8081/api/email/send

• PUTRequest

  [
    "dd178821-15c6-45c2-9b97-7df4d1ce73d1",
    "8b065a35-b305-49e9-b601-2e7ecbe84f4f",
    "97095a32-h602-47b2-l205-6h0ecke24j4j"
    ]
    

Assumption

• Application will be Running in UTC TimeZone
• I will be having some Api to identify Users Local TimeZone and equivalent UTC time.
• User always sending correct Channel names during Adding channel, no validation done for checking valid channel names.
• No failure in third party system (Ahh!!! this is big one)

Improvement Required in current implementation

• Proper exception handling.
• Proper User response during exception in API.
• Using Circuit breaker during calling third party API.
• Fault tolerance, handle failure scenario.
• Retry logic during failure.
• Transaction handling.
• Code refactoring.
• Proper Logging for debugging.
• Monitoring and health check dashboard the API.
• API documentation as code.
• Executor service to send email in parallel to the USER.
• Adding Integration test.
• Add more Unit Test.