Under the Hood of Reactive Data Access

Slides to the presentation I gave at Spring I/O 2018

Conference page: https://2018.springio.net/sessions/under-the-hood-of-reactive-data-access
GitHub repository: https://github.com/mp911de/under-the-hood-reactive

Transcript

1. Mark Paluch @mp911de UNDER THE HOOD OF REACTIVE DATA ACCESS
2. Spring Data Modules JPA
3. Reactive Spring Data Modules JPA
4. What about… JDBC? JPA?
5. Relational Databases •Not a good fit for reactive access •Limited scalability •Resource synchronization •ACID Transactions
6. JDBC •Fully blocking API •Non-blocking API announced: ADBA 
 (JDK-8188051) http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/ • JDK-8188051: http://hg.openjdk.java.net/jdk/sandbox/shortlog/JDK-8188051-branch
7. Query Behavior
8. Query by Time Transport
9. Synchronous Data Access Data store App Data store App Data store
10. Reactive Data Access Data store App Data store Data store Data store App
11. Differences to imperative Data Access •Drivers require threading infrastructure •Timeout handling different
12. Synchronous Timeouts Socket.setSoTimeout(…) ⏱
13. Aynchronous Timeouts •Active timeout tracking required
14. Reactive Drivers •End-to-end nonblocking •Asynchronous request-response processing •Non-blocking pooling •Non-blocking connect
15. Application Driver Application Request Server selection Queueing Write Response decoding Response buffering Request completion Response
16. Reactive NoSQL drivers
17. MongoDB •Reactive-over-async driver •Cursor lifecycle •Pluggable I/O •Pooled connections Java.NIO
18. Query by Time Request Response (chunk) Response (complete) Prefetch (cont.d) Query Emit elements Result processing
19. MongoDB Driver Fetching Operator MongoDB Subscriber request(Long.MAX_VALUE) request(Long.MAX_VALUE)
20. MongoDB Driver Fetching Filter MongoDB Subscriber request(Long.MAX_VALUE) request(Long.MAX_VALUE)
21. MongoDB Driver Fetching Filter MongoDB Subscriber request(Long.MAX_VALUE) request(1) Dropped element
22. Specific Features •Cursor size derived from demand •Tailable Cursors (@Tailable) •MongoDB 3.6: Change Streams
23. Redis •Reactive driver (Lettuce 5) •Based on Netty and Project Reactor •Singleton connection •Optionally: Pooled connections
24. Command by Time Request Command Command (subscription) Response (chunk) Response (complete)
25. Specifics •Use ByteBuffer instead byte[] •null handling: Emission of empty buffers •Suspend reading if no demand
26. Apache Cassandra •Reactive bridge over async driver •Netty-based driver (Datastax) •Pooled connections
27. Query by Time Request Response (chunk) Response (complete) Query Emit elements Result processing Next page
28. Outlook •Cassandra driver 4.0 in the works •Likely support for reactive execution model •Emit items as they are received https://github.com/datastax/java-driver/tree/4.x • https://datastax-oss.atlassian.net/browse/JAVA-1505
29. Couchbase •Reactive driver driver •Based on Netty and RxJava 1 •Multiple connection schemes
30. Key-Value, DCP •Request •Response •Emit results
 Search, Query, View •Request •Response streaming
31. Command by Time Request Command Command (subscription) Response (chunk) Response (complete)
32. Outlook •Couchbase driver likely to move to RxJava 2 •No tickets/decisions yet
33. Imperative and Reactive Together
34. Blocking with Imperative Programming
35. Blocking with Reactive Programming
36. Imperative and Reactive @Component public class ApplicationInitializer { ReactiveMongoOperations ops; @PostConstruct public void postConstruct() { ops.remove(Person.class).all().block(); } }
37. Imperative and Reactive @Component public class ApplicationInitializer { ReactiveMongoOperations ops; @PostConstruct public void postConstruct() { ops.remove(Person.class).all().block(); } }
38. Event Loop Event Loop (single Thread)
39. Event Loop Event Loop (single Thread)
40. Event Loop Process next item Callback Register Callback Return Work Database Computation File I/O Event Loop (single Thread) Work Queue Work Request Callback
41. Event Loop Process next item Callback Work Event Loop (single Thread) Work Queue Request Callback
42. Event Loop Event Loop (single Thread) Work Queue Process next item Work Callback Work Wait for Request completion Return Request Request Callback
43. Event Loop Event Loop (single Thread) Work Queue Process next item Work Callback Work Wait for Request completion Return Request Request Callback
44. Thou shalt not block
45. Resources •Slides – mp911.de/uhd-springio18 •Example Code – mp911.de/uhd-code •Spring Data Examples – Repository @ Github •Find us on Gitter!
46. Mark Paluch @mp911de THANKS!