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The "Reactive with Observables" Lesson is part of the full, Reactive Angular 2 with ngrx course featured in this preview video. Here's what you'd learn in this lesson:

In the observer pattern, an object (called the subject) maintains a list of its dependents (called observers). These observers are notified automatically of any changes in state. After giving a brief explanation of observers, Scott introduces the RxJS library and shares a basic code example that uses a few of the RxJS operations.

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