HappyHeadlines

Comment Service

Fault Isolation: Retry and Circuit Breaker Patterns in CommentService using Polly

The CommentService depends on the ProfanityService to filter comment text before storing it. We've implemented a circuit breaker pattern into the CommentService to take over if the ProfanityService is no longer available.

Policies with Polly

We use Polly to protect calls:

1. Retry Policy

   • Retries up to 3 times with exponential backoff (200ms, 400ms, 800ms).
   • Covers transient network issues or short hiccups.

2. Circuit Breaker Policy

   • Trips after 2 consecutive failures.
   • Remains OPEN for 10 seconds (fail-fast).
   • While OPEN, all calls fail immediately with 503 Service Unavailable.
   • After 10s, transitions to HALF-OPEN → allows a single trial request.
   • If the trial succeeds, the breaker closes (normal traffic resumes).
   • If it fails, the breaker reopens for another 10s.

Client Behavior

• Normal (Closed) → Comments are filtered, persisted, and returned.
• Failure (Breaker Open) → Requests fail immediately with:

  { "error": "ProfanityService unavailable. Please try again shortly." }
  
  

Profanity Service

The ProfanityService filters comment text from profanity words and returns a clean profanity free comment to CommentService.