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.

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.