Flowable and back pressure

Backpressure : 

The process of handling a fast item producer means it allows to control how fast a source emits items


RxJava 2 introduced Flowable to represent backpressure-aware sources using a dedicated class

Flowable : 

It is type of observables which emits 0 or n items and terminates with an success or an error event.
Supports backpressure.

Creating Flowables :

Simple Flowable : 

1. We can create a Flowable using the just() method.

Flowable from Observable : 

1.  Observable we can be easily transform to Flowable using the toFlowable() method.

Flowable from FlowableOnSubscribe : 

1. RxJava 2 introduced a functional interface FlowableOnSubscribe, which represents a Flowable that starts emitting events after the consumer subscribes to it.

Backpressure Strategy:

Dropping

1. Discards the unrequested items if it exceeds the buffer size.

Latest : 

1. Preserve the latest item
2. It is type of observables which emits 0 or n items and terminates with an success or an error event.
3. Supports backpressure.

Buffring : 

1. Buffers all the items from the producer, watch for OOMs.
2. Error throws a MissingBackpressureException in case of over emission

Missing: 

1. No strategy, it would throw a MissingBackpressureException sooner or later somewhere on the downstream

Reactive Pull

In reactive pull, subscriber requests required number of items from observable by calling request()