SubscribeOn

specify the Scheduler on which an Observable will operate

SubscribeOn

Many implementations of ReactiveX use Schedulers” to govern an Observable’s transitions between threads in a multi-threaded environment. You can instruct an Observable to do its work on a particular Scheduler by calling the Observable’s SubscribeOn operator.

The ObserveOn operator is similar, but more limited. It instructs the Observable to send notifications to observers on a specified Scheduler.

In some implementations there is also an UnsubscribeOn operator.

ObserveOn and SubscribeOn

By default, an Observable and the chain of operators that you apply to it will do its work, and will notify its observers, on the same thread on which its Subscribe method is called. The SubscribeOn operator changes this behavior by specifying a different Scheduler on which the Observable should operate. The ObserveOn operator specifies a different Scheduler that the Observable will use to send notifications to its observers.

As shown in this illustration, the SubscribeOn operator designates which thread the Observable will begin operating on, no matter at what point in the chain of operators that operator is called. ObserveOn, on the other hand, affects the thread that the Observable will use below where that operator appears. For this reason, you may call ObserveOn multiple times at various points during the chain of Observable operators in order to change on which threads certain of those operators operate.

See Also

Language-Specific Information:

subscribeOn

To specify on which Scheduler the Observable should operate, use the subscribeOn operator, passing it the appropriate Scheduler.

To specify which Scheduler observers will use to unsubscribe from an Observable, use the unsubscribeOn operator, passing it the appropriate Scheduler.

subscribeOn

To specify on which Scheduler the Observable should operate, use the subscribeOn operator, passing it the appropriate Scheduler.

To specify which Scheduler observers will use to unsubscribe from an Observable, use the unsubscribeOn operator, passing it the appropriate Scheduler.

subscribeOn

To specify on which Scheduler the Observable should operate, use the subscribeOn operator, passing it the appropriate Scheduler.

Sample Code

/* Change from immediate scheduler to timeout */
var source = Rx.Observable.return(42, Rx.Scheduler.immediate)
    .subscribeOn(Rx.Scheduler.timeout);

var subscription = source.subscribe(
    function (x) { console.log('Next: ' + x); },
    function (err) { console.log('Error: ' + err); },
    function () { console.log('Completed'); });
Next: 42
Completed

subscribeOn is found in each of the following distributions:

  • rx.js
  • rx.all.js
  • rx.all.compat.js
  • rx.compat.js
  • rx.lite.js
  • rx.lite.compat.js