The observer pattern is a Gang of Four design pattern and one of the most interesting patterns in design pattern. this pattern listed under Behavioral Patterns.
Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.This pattern suitable push-based notifications.
you can watch youtube video related observer design pattern’s logic.I recommend this.
and you can find a great technical post via codeproject.In this post you’ll see example blog subscriber with observer pattern.I made three example for this.
you can examine implementation observer pattern with generic structure
have a good codeday 😀