Quarkus Insights 2023-03-06

Transcript

1. java.util.stream.*
   java.util.concurrent.Flow.*
   2 kinds of “stream” APIs
   Efficient in-memory
   
   
   data stream processing
   Backpressured async I/O
   
   
   data stream processing
   

   View Slide

2. “Reactive Streams is an initiative to provide a
   standard for asynchronous stream
   processing with non-blocking back pressure.”
   
   
   — https:/
   /www.reactive-streams.org/
   Mutiny!
   Photo by Arno Senoner on Unsplash
   

   View Slide

3. org.reactivestreams.*
   
   
   (Java 6 legacy)
   java.util.concurrent.Flow.*
   
   
   (since JDK 9)
   Back-pressured, asynchronous, non-blocking
   
   
   (see Reactive Streams TCK)
   < your own library / client / driver / … >
   APIs
   Protocol
   User-facing
   
   
   APIs
   

   View Slide

4. return flux
   
   
   .filter(n
   ->
   n % 2
   ==
   0)
   
   
   .map(n
   ->
   "[" + n + "]")
   
   
   .flatMap(Database
   ::
   record)
   
   
   .retry(5);
   return multi
   
   
   .select().where(n
   ->
   n % 2
   ==
   0)
   
   
   .onItem().transform(n
   ->
   "[" + n + "]")
   
   
   .onItem().transformToUniAndMerge(Database
   ::
   record)
   
   
   .onFailure()
   
   
   .retry()
   
   
   .withBackOff(Duration.ofSeconds(1))
   
   
   .atMost(5);
   
   
   RxJava / Reactor Mutiny
   Functional dialect,
   fl
   at 100+ methods list
   Event-based dialect,
   group-based api
   

   View Slide

5. Ok, 4 interfaces. Must be easy, right?
   Publisher Subscriber
   Processor Subscription
   

   View Slide

6. View Slide

7. View Slide

8. View Slide

9. View Slide

10. View Slide

11. Migrate to Flow
    Use adapters
    Strategies: from legacy to Flow
    Support both APIs
    New APIs. Same TCK.
    Best for 3rd-party libraries
    
    
    that haven’t migrated yet.
    
    
    Virtually no-cost.
    Transition for user code:
    
    
    RESTEasy Reactive,
    
    
    Reactive Messaging, …
    

    View Slide

12. Mutiny Zero
    (44 Kilobytes JAR)
    RS <-> Flow
    
    
    Mutiny Zero Adapters
    Vert.x -based
    
    
    stream publishers
    Mutiny Zero
    
    
    — minimal helper libraries to make publishers
    

    View Slide