Polly: Practical Patterns for Resilient .NET Applications

"Polly: Practical Patterns for Resilient .NET Applications" is a practical guide for software professionals who want to build resilient .NET systems that can withstand transient faults, partial outages, and the unpredictability of modern distributed architectures. The book introduces the core principles of resilience engineering, explains how Polly fits into the .NET ecosystem, and provides a clear foundation in error taxonomy, policy selection, and the patterns that make fault handling both intentional and effective. Readers will learn how to think about resilience not as an afterthought, but as a first-class design concern for microservices, serverless workloads, and cloud-native applications. From there, the book explores the most important resilience strategies in depth, including retries, circuit breakers, timeouts, bulkheads, and fallbacks. It shows how to combine these patterns thoughtfully to improve reliability without introducing unnecessary complexity, while also addressing critical topics such as idempotency, context-aware execution, dynamic configuration, and layered policy orchestration. Real-world examples and implementation guidance help readers apply these techniques confidently across a variety of scenarios, from latency-sensitive services to systems that must degrade gracefully under pressure. The final chapters focus on operating Polly effectively in production, with guidance on observability, diagnostics, telemetry, and performance-aware policy design. Readers will also find practical advice for testing resilience through fault injection, chaos engineering, and automated validation, along with strategies for deploying resilient policies at scale in Kubernetes, service meshes, and multi-region environments. By combining architectural insight with hands-on patterns and operational best practices, the book equips developers, architects, and operations teams to build and sustain robust .NET applications in the real world.