Let's imagine we're building a crucial component for monitoring and maintaining the health of various microservices or external APIs within a larger system. This component, the "Endpoint Poller Service," is responsible for periodically invoking a specified endpoint (e.g., a REST API) and recording the response. Think of it as a heartbeat monitor that can be configured to check any URL at a defined interval. The responses could then be processed to create health dashboards or trigger alerts if an endpoint becomes unresponsive or returns an error.

This problem emphasizes a robust, extensible, and thread-safe design. How can we create a modular service that can accommodate various endpoint types (REST, GraphQL, etc.), authentication schemes, and response processing strategies without requiring significant code modifications? We need to think about how to manage multiple pollers concurrently, handle errors gracefully, and allow for future expansion with new endpoint types or response validation rules. Let's focus on designing the core poller logic, leaving the UI/configuration aspects out of scope.

Requirements