How do ColdPublisher and HotPublisher differ in principles and application?

ColdPublisher and HotPublisher are concepts in reactive programming that describe the behavior of data streams (publishers) concerning subscribers.

ColdPublisher:

• Starts generating data only after subscription.
• Each subscriber receives the full data stream from the beginning.
• Example: Observable that starts emitting values anew upon subscription.

HotPublisher:

• Generates data independently of subscribers.
• Subscribers receive data from the current moment, skipping previous events.
• Example: a user interface event stream that constantly generates events.

Application:

• ColdPublisher is suitable for operations where each subscriber should receive the complete set of data (e.g., data loading).
• HotPublisher is used for events that occur constantly and do not depend on subscribers (e.g., UI updates, sensors).

Thus, the main difference is the moment of data generation start and whether subscribers receive the entire history or only current events.