1. Reactive Extensions
for .NET
Andrei Marukovich
contact@lunarfrog.com
twitter: @amarukovich

2. Rx is a library for composing
asynchronous and event-based
programs using observable sequences
and LINQ-style query operators.
Rx = Observables + LINQ + Schedulers

3. Observables
• IObservable<T>
• IObserver<T>

4. Enumerables
interface IEnumerable<out T>
{
IEnumerator<T> GetEnumerator();
}
interface IEnumerator<out T> : IDisposable
{
T Current { get; }
bool MoveNext();
void Reset();
}

5. Pull and Push
Consumer
Pull
Any new data?
IEnumerable
•
•
•
•
Sensors
UI events
Web services
Social media
Source
IObservable
Push
New data available!

6. Observables
interface IObservable<out T>
{
IDisposable Subscribe(IObserver<T> observer);
}
interface IObserver<out T>
{
void OnNext(T value);
void OnError(Exception error);
void OnCompleted();
}

7. Using observables
IObservable
IObserver
Subscribe
OnNext
OnNext
OnComplete

8. Contract
OnNext* [OnComplete | OnError]
1
2
1
3
2
1
2
1
2 3
4
3
3
4
4
5
6

9. Demo: Observable sequences
• Subject<T>
• Observable
• Never, Empty, Return, Throw, Create
• Range, Generate, Repeat
• Interval, Timer

10. LINQ
Filtering
• Where, Distinct, Skip(While|Last|Until), Take
Inspection
• Any, All
Aggregation and transformation
• Count, Min, Max, Average, Select

11. Demo: LINQ
• Common LINQ operators
• Combining sequences
• Pairing
• Sequentially
• Concurrently

12. Rx bridges
• Observable.FromAsync()
• Observable.FromEvent()
• Observable.FromEventPattern()

13. Demo: LINQ to events
• Time shifting
• Throttle
• Sample
• Buffer
• Delay

14. Concurrency
SubscribeOn
• Invocation of the subscription
ObserveOn
• Observing of notifications

15. Demo: Concurrency
• Schedulers

16. Schedulers
• ImmediateScheduler
• CurrentThreadScheduler
• DispatcherScheduler
• EventLoopScheduler
• NewThreadScheduler
• Thread/Task Pool
• TestScheduler

17. Flavors of Rx
.NET
• WinForms, WPF, Silverlight
• Windows Phone, WinRT
• ASP
.NET
Beyond .NET
• RxJS, RxCpp
• RxPy, Rx.rb

18. Resources
• http://rx.codeplex.com/
• http://bit.ly/Rx-Home

19. Thank you!
Andrei Marukovich
contact@lunarfrog.com
twitter: @amarukovich