Polly is a .NET library that provides a framework for handling transient faults in an application. It allows developers to implement retry policies, circuit breakers, timeouts, and other fault-handling patterns in a clean, composable, and declarative way. In this post, we'll explore what Polly is, why it’s valuable, and how to use it in .NET Core applications to build resilient, fault-tolerant solutions.
What is Polly?
Polly is an open-source library that enables you to build fault-handling and resilience logic into your applications. It helps you manage faults and unexpected scenarios by providing a range of resilience policies. Polly works seamlessly with .NET Core and can be used across HTTP clients, database calls, message queues, and more. Here are the key policies Polly supports:
- Retry: Retry a failed operation multiple times before giving up.
- Circuit Breaker: Stop calling a failing service temporarily to give it time to recover.
- Timeout: Fail if an operation takes longer than a specified time.
- Fallback: Provide an alternative response or behavior when an operation fails.
- Bulkhead Isolation: Limit concurrent executions to avoid resource exhaustion.
- Cache: Cache responses to avoid repeated calls for the same result.
By combining these policies, Polly enables you to create robust and customizable resilience strategies tailored to your application’s needs.
Why Use Polly?
In any distributed application, you’ll inevitably encounter issues like network instability, service unavailability, or rate limiting. Polly allows you to handle these scenarios without excessive code and helps:
