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I'm trying to understand the difference between "observer" vs. "notify" in Polymer properties block, and also how they differ from "observers" and "listeners". The online documentation does not seem to elaborate on them.
Could someone explain this to me?
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The pattern also does not deal with recording when change notifications are sent or guaranteeing that they are being received. These concerns are typically handled in message queueing systems of which the observer pattern is only a small part. Related patterns: Publish–subscribe pattern, mediator, singleton .
In those systems, the subject is usually named a "stream of events" or "stream source of events", while the observers are called "sinks of events". The stream nomenclature alludes to a physical setup where the observers are physically separated and have no control over the emitted events from the subject/stream-source.
The responsibility of observers is to register (and unregister) themselves on a subject (to get notified of state changes) and to update their state (synchronize their state with the subject's state) when they are notified. This makes subject and observers loosely coupled.
The responsibility of observers is to register (and unregister) themselves on a subject (to get notified of state changes) and to update their state (synchronize their state with the subject's state) when they are notified. This makes subject and observers loosely coupled. Subject and observers have no explicit knowledge of each other.
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