Mastering Sync Communication

Synchronous communication is easy to reason about but can lead to Cascading Failures. If Service A waits for Service B, and B is slow, Service A will eventually crash too.

1. HTTP vs gRPC

• HTTP/JSON: Best for Public APIs. It's human-readable and universal. However, JSON parsing is slow and text-heavy.
• gRPC (HTTP/2): Industry standard for internal service-to-service communication. It uses binary serialization (Protobuf), which is 5x-10x faster than JSON. It also supports streaming and bi-directional communication.

2. The Service Mesh (Istio / Linkerd)

A Service Mesh is an infrastructure layer that handles communication for you. It provides **Automatic Retries**, **Mutual TLS**, and **Observability** without you writing any code in your .NET service. It essentially puts a 'Sidecar' proxy next to every pod to manage the network traffic.

4. Interview Mastery

Q: "When should you NOT use gRPC?"

Architect Answer: "gRPC is difficult for browsers to use directly (requires gRPC-Web). If your primary client is a Frontend/Mobile app, a normal REST/HTTP API is often better. Use gRPC for 'Backend-to-Backend' communication where performance and type safety are critical, but keep your public-facing gateway on REST."