Reactive Data Access with RxJava... and N1QL!

Reactive Data Access with RxJava... and N1QL!

This talk, given at JDK.io (recording may be available through them at some point) is a whirlwind introduction to RxJava, N1QL and reactive programming in general. It also talks about resiliency and various patterns you are likely to need.

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Michael Nitschinger

September 14, 2016
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Transcript

  1. Reactive Data Access with RxJava …and N1QL! Michael Nitschinger, Couchbase

    Inc. @daschl
  2. ©2016 Couchbase Inc. 2 § New challenges §  React to user

    load §  React to failure §  Be responsive under load and failure § Need new solutions §  Decoupled, event-driven architectures §  Optimal resource utilization Reactive? 2
  3. ©2016 Couchbase Inc. 3 3

  4. ©2016 Couchbase Inc. 4 §  RxJava 1 §  Reactive Streams

    (http://www.reactive-streams.org/) §  RxJava 2 §  Reactor 3 §  Akka Streams The Reactive Landscape 4
  5. ©2016 Couchbase Inc. 5 Detour: N1QL 5 §  Declarative Query

    Language §  Extends SQL for JSON §  Query UI Built-In §  Full SDK Support §  Based on performant Global Secondary Indexes
  6. ©2016 Couchbase Inc. 6 Detour: N1QL 6

  7. ©2016 Couchbase Inc. 7 Detour: N1QL 7

  8. ©2016 Couchbase Inc. 8 Detour: Async Java Client Stack 8

  9. ©2016 Couchbase Inc. 9 Detour: Smart Batching Source: http://mechanical-sympathy.blogspot.co.at/2011/10/smart-batching.html 9

  10. ©2016 Couchbase Inc. 10 Detour: Smart Batching Source: http://mechanical-sympathy.blogspot.co.at/2011/10/smart-batching.html 10

  11. RxJava 101 A Gentle Introduction

  12. ©2016 Couchbase Inc. 12 §  Java implementation for Reactive Extensions

    https://github.com/ReactiveX §  A library to compose asynchronous and event-driven programs through observable sequences. RxJava: Introduction single multiple sync T Iterable<T> async Future<T> Observable<T> 12
  13. ©2016 Couchbase Inc. 13 §  Observables are the duals of

    Iterables §  They describe both Latency and Error side effects. RxJava: Introduction event Iterable<T> (pull) Observable<T> (push) data retrieval T next() onNext(T) error discovery throws Exception onError(Exception) completion returns onCompleted() 13
  14. ©2016 Couchbase Inc. 14 Consuming Observables 14 §  The Subscriber

    subscribes and receives events. §  A cold Observable starts when subscribed. §  onNext can be called 0..N times
  15. ©2016 Couchbase Inc. 15 Single 15 §  Behaves like an

    Observable §  Emits only a single successful value or an error
  16. ©2016 Couchbase Inc. 16 Completable 16 §  Signals Completion or

    Error for a deferred computation.
  17. ©2016 Couchbase Inc. 17 RxJava: Creating Observables just 17

  18. ©2016 Couchbase Inc. 18 RxJava: Creating Observables 18

  19. ©2016 Couchbase Inc. 19 RxJava: Creating Observables 19

  20. ©2016 Couchbase Inc. 20 RxJava: Creating Observables 20

  21. ©2016 Couchbase Inc. 21 RxJava: Filtering Observables 21

  22. ©2016 Couchbase Inc. 22 RxJava: Filtering Observables 22

  23. ©2016 Couchbase Inc. 23 RxJava: Filtering Observables 23

  24. ©2016 Couchbase Inc. 24 RxJava: Filtering Observables 24

  25. ©2016 Couchbase Inc. 25 RxJava: Transforming Observables 25

  26. ©2016 Couchbase Inc. 26 RxJava: Transforming Observables 26

  27. ©2016 Couchbase Inc. 27 RxJava: Transforming Observables 27

  28. ©2016 Couchbase Inc. 28 RxJava: Transforming Observables 28

  29. ©2016 Couchbase Inc. 29 RxJava: Transforming Observables 29

  30. ©2016 Couchbase Inc. 30 RxJava: Transforming Observables 30

  31. ©2016 Couchbase Inc. 31 RxJava: Transforming Observables 31

  32. Reactive N1QL Cranking Queries up to Eleven!

  33. ©2016 Couchbase Inc. 33 § Simple §  Executes a single N1QL

    statement, no options available. § Parameterized §  Executes a parameterized query with positional or named params §  Prepared Query supported through adhoc(false) Query Types 33
  34. ©2016 Couchbase Inc. 34 § (Async) N1qlQueryResult §  Observable<AsyncN1qlQueryRow> rows() § 

    Observable<JsonObject> errors() §  Observable<N1qlMetrics> info() §  Observable<Object> signature() §  Observable<Boolean> finalSuccess() §  Observable<String> status() §  boolean parseSuccess() §  String requestId() §  String clientContextId() Query Response 34
  35. ©2016 Couchbase Inc. 35 Simple Query 35

  36. ©2016 Couchbase Inc. 36 Parameterized Query 36 § Named Params

  37. ©2016 Couchbase Inc. 37 Parametrized Query 37 § Positional Params

  38. ©2016 Couchbase Inc. 38 Index Handling 38

  39. ©2016 Couchbase Inc. 39 Index Handling 39

  40. ©2016 Couchbase Inc. 40 Conditional Index Creation 40

  41. ©2016 Couchbase Inc. 41 Transparent Query Caching 41

  42. Error Handling with RxJava

  43. ©2016 Couchbase Inc. 43 § Things will go wrong, so better

    plan for it § Do not trust integration points (including the SDK) § Synchronous retry & fallback is too damn hard § RxJava provides (almost) everything you need to §  fallback §  retry §  fail fast Preparing to Fail 43
  44. ©2016 Couchbase Inc. 44 Timeouts 44 § The network is unreliable

    § Servers fail § The SDK contains bugs § Always specify timeouts and deal with them! § The synchronous wrapper defines them for you all the time.
  45. ©2016 Couchbase Inc. 45 Timeouts: Simple 45

  46. ©2016 Couchbase Inc. 46 Timeouts: Synchronous API 46

  47. ©2016 Couchbase Inc. 47 Timeouts: Complex Example 47

  48. ©2016 Couchbase Inc. 48 Timeouts: Complex Example 48

  49. ©2016 Couchbase Inc. 49 Coordinated Retry 49 §  Fail fast

    §  Don’t let your system get stuck §  Shed load with backpressure § Retry §  immediately won’t help §  either linear or exponential back-off necessary §  have a strategy if retry also doesn’t work (Fallbacks!)
  50. ©2016 Couchbase Inc. 50 Coordinated Fallback 50

  51. ©2016 Couchbase Inc. 51 Coordinated Retry: Builder 51 §  Declarative

    API instead of complicated retryWhen
  52. Thank you.