This document discusses reactive programming and asynchronous operations. It introduces Vert.x and examples of asynchronous database queries using Vert.x and MUTINY. MUTINY provides reactive streams APIs like Uni and Multi that allow expressing asynchronous logic through events like onItem, onFailure, and onCompletion without blocking or callback hell. Examples demonstrate reactive database querying and service APIs using MUTINY.

1. A Reactive MUTINY!

2. Why does
reactive matter?

6. Events, a LOT of
Events

7. sharing deployment density
Container Host
Threads
costs memory
cost lots of memory
cost CPU cycles
+ quotas = BOOM

8. Use resources
efficientlyNon-Blocking IO
On event X Do YEvent-driven

9. Non-Blocking IO (Netty)
Reactive Framework
Run on the IO Thread
} 1 Thread

10. How do we tame
the asynchronous
beast

11. vertx.createHttpServer()
.requestHandler(req -> // Async reaction
req.response().end("Reactive Greetings")
)
.listen(8080, ar -> { // Async operation
//...
});

12. Hell!
client.getConnection(conn -> {
if (conn.failed()) {/* failure handling */}
else {
SQLConnection connection = conn.result();
connection.query("SELECT * from PRODUCTS",
rs -> {
if (rs.failed()) {/* failure handling */}
else {
List<JsonArray> lines = rs.result().getResults();
for (JsonArray l : lines) { System.out.println(new Product(l)); }
connection.close(
done -> {
if (done.failed()) {/* failure handling */}
});
}
});
}
});

13. client.rxGetConnection() // Single(async op)
.flatMapPublisher(conn ->
conn
.rxQueryStream( "SELECT * from PRODUCTS")
.flatMapPublisher(SQLRowStream::toFlowable)
.doAfterTerminate(conn::close)
) // Flowable of Rows
.map(Product:: new) // Flowable of Products
.subscribe(System. out::println);

14. jungle
client.rxGetConnection() // Single(async op)
.flatMapPublisher(conn ->
conn
.rxQueryStream( "SELECT * from PRODUCTS")
.flatMapPublisher(SQLRowStream::toFlowable)
.doAfterTerminate(conn::close)
) // Flowable of Rows
.map(Product:: new) // Flowable of Products
.subscribe(System. out::println);

15. MUTINY!
Event-Driven
onItem()
onFailure()
onCancellation()
onCompletion()
Navigable
The API guides you
Number of methods
per class
EXPRESSIVENESS
Express your logic
Avoid maths

16. service.order(order)
.onItem().apply(i -> process(i))
.onFailure().recoverWithItem(fallback)
.subscribe().with(
item -> ...
);
MUTINY!
Uni
Uni
Uni
Sub.

17. Uni
1 item or failure
Async operation
MUTINY!
Events
MULTI
0..n item or 1 failure
Back-pressure
Item*,
Failure,
Completion
Subscription,
Cancellation,
Request
Upstream
Downstream

18. Show me
some CODE!

19. SUPES-DEMO!
Supes
Service
Mongo
Fight
Service
Stats
Service
SSE
endpoint
REST & SSE
endpoint
HTTP