juniorReactive Systems
What is an Observable?
Updated Apr 28, 2026
Short answer
A data producer that emits items over time to an observer that reacts to them.
Deep explanation
Reactive systems are designed to handle the uncertainty of distributed environments. While reactive programming (like RxJS) helps manage local state changes, reactive systems focus on the whole architecture. The message-driven nature is the foundation that enables elasticity and resilience.
Real-world example
A search bar that provides suggestions as you type without freezing the UI.
Common mistakes
- Confusing 'Elasticity' (dynamic scaling) with 'Scalability' (capability to grow).
Follow-up questions
- How does backpressure prevent OutOfMemory errors?