Explain Cold vs Hot Observables.
Updated Apr 28, 2026
Short answer
Cold observables start producing data upon subscription; Hot observables produce data regardless of subscribers (like a radio broadcast).
Deep explanation
Mid-level reactive architecture moves into distributed coordination. The Actor model is a classic implementation of the message-driven trait. Actors encapsulate state and behavior, and because they only communicate via messages, they can be easily scaled across a cluster (Location Transparency).
Real-world example
A microservice architecture where the 'Orders' service can crash without affecting the 'User Profile' service (Resilience via Bulkheading).
Common mistakes
- Sharing mutable objects between actors, which breaks the isolation principle.
Follow-up questions
- What is the difference between a Task and an Actor?