Flow.Subscription (Java SE 12 & JDK 12 )

Enclosing class:

Flow
```
public static interface Flow.Subscription
```
Message control linking a Flow.Publisher and Flow.Subscriber. Subscribers receive items only when requested, and may cancel at any time. The methods in this interface are intended to be invoked only by their Subscribers; usages in other contexts have undefined effects.

Method Summary

Modifier and Type	Method	Description
`void`	`cancel()`	Causes the Subscriber to (eventually) stop receiving messages.
`void`	`request(long n)`	Adds the given number `n` of items to the current unfulfilled demand for this subscription.

- Method Detail
  - request
```
void request(long n)
```
    Adds the given number n of items to the current unfulfilled demand for this subscription. If n is less than or equal to zero, the Subscriber will receive an onError signal with an IllegalArgumentException argument. Otherwise, the Subscriber will receive up to n additional onNext invocations (or fewer if terminated).
    
    Parameters:
    
    n - the increment of demand; a value of Long.MAX_VALUE may be considered as effectively unbounded
  - cancel
```
void cancel()
```
    Causes the Subscriber to (eventually) stop receiving messages. Implementation is best-effort -- additional messages may be received after invoking this method. A cancelled subscription need not ever receive an onComplete or onError signal.