| Interface | Description | 
|---|---|
| Completable | Interface that exposes a callback to indicate when an operation has been completed. | 
| Emitter<T> | Base interface for classes that emit data. | 
| Class | Description | 
|---|---|
| CompletionAwareSubscriber<T> | A  Subscriberthat tracks completion state using aAtomicBoolean. | 
| SingleThreadedBufferingSubscriber<T> | A  Subscriberdesigned to be used by a single thread that buffers incoming data for the purposes of managing
 back pressure. | 
| TypedSubscriber<T> | A subscriber that is aware of the target type. | 
| Enum | Description | 
|---|---|
| SingleThreadedBufferingSubscriber.BackPressureState | Back pressure state. |