Going Reactive with gRPC

GOING REACTIVE
WITH GRPC
ANDRES ALMIRAY
@AALMIRAY
ANDRESALMIRAY.COM

@aalmiray
JCP Executive Committee Associate Seat
Committer
Committer
JSR377 Specification Lead

@aalmiray
STATE
Imperative Programming (Procedural)
var a := b + c
println a
Declarative Programming (Functional)
(println (sum(b, c))

@aalmiray
TIME
Imperative Programming
var a := b + c
println a
Reactive Programming
var a := b + c
a.done( v -> println v)

@aalmiray
SYNC VS ASYNC
Synchronous operations block the flow until they yield a
result (success or error).
Asynchronous operations DO NOT block the flow, rather they
allow the program to continue. Results (or errors) will be
handled at a later point in time, typically using functions
(callbacks).

@aalmiray
FUTURES AND PROMISES
They describe an object that acts as mediator for a value that
may be unknown at init time.
The terms Future and Promise are normally used
interchangeably but there’s a difference:
• A Future is a read-only reference of the expected value.
• A Promise is a write-once container that sets the value of
the Future.
https://en.wikipedia.org/wiki/Futures_and_promises

@aalmiray
Futures in Java are synchronous, this can be demonstrated
by the following method signatures found in
java.util.concurrent.Future
V get()
V get(long timeout, TimeUnit unit)

@aalmiray
Java 8 added a new type, CompletableFuture, that
implements CompletableStage, which in turns defines the
contract of a Promise, such as
thenAccept(Consumer<? Super T> action)
whenComplete(BiConsumer<? super T,? super Throwable>
action)
exceptionally(Function<Throwable,? extends T> fn)
… and many others

@aalmiray
JDeferred offers a different API that allows better function
composition
Promise<D, F, P> then(DoneCallback<D> doneCallback)
Promise<D, F, P> done(DoneCallback<D> callback)
Promise<D, F, P> fail(FailCallback<F> callback)
Promise<D, F, P> always(AlwaysCallback<D, F> callback)

@aalmiray
DATA STREAMS
A sequence of values calculated over time.
Values are emitted when ready; they are computed without
blocking consumers.
Consumers listen to changes in the data stream and react to
said changes (hence the name Reactive Programming).
Push vs pull model.

@aalmiray
OBSERVABLE/OBSERVER
Data streams are of type Observable while consumer are of
type Observer.
The Observable type exposes multiple operations that allow
value composition, combinations, filtering, and other value
transformations.
NOTE: many operations from RxJava/Reactor generate a new
Observable (decorator pattern)

@aalmiray
OPERATIONS
(A SMALL SAMPLE OF)

@aalmiray
HTTP://RXMARBLES.COM

@aalmiray
HTTP://REACTIVEX.IO/RXJAVA/2.X/JAVADOC/INDEX.HTML

@aalmiray
HTTPS://GRPC.IO/
gRPC is a modern, open source, high-performance remote
procedure call (RPC) framework that can run anywhere. It
enables client and server applications to communicate
transparently, and makes it easier to build connected
systems.

@aalmiray
RXGRPC
https://github.com/salesforce/reactive-grpc
Combines gRPC with Reactive Streams
Encapsulates gRPC’s API
Producers/Consumers only see Rx API

@aalmiray
DEMO
HTTPS://GITHUB.COM/AALMIRAY/HELLO-GRPC/

@aalmiray
RESOURCES
http://download.java.net/java/jdk9/docs/api/java/util/concurrent/Flow.ht
ml
http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/Completab
leFuture.html
http://jdeferred.org/
http://andresalmiray.com/articles/jdeferred-simple-handling-of-
promises-and-futures/
http://andresalmiray.com/articles/testing-rxjava2/
https://www.infoq.com/articles/rxjava2-by-example

@aalmiray
REACTIVE
PROGRAMMING
IMPLIES AND
PARADIGM
CHANGE!

@aalmiray
HTTP://ANDRESALMIRAY.COM/NEWSLETTER
HTTP://ANDRESALMIRAY.COM/EDITORIAL

THANK YOU!
ANDRES ALMIRAY
@AALMIRAY
ANDRESALMIRAY.COM

Going Reactive with gRPC

Going Reactive with gRPC

Recommended

More Related Content

What's hot

What's hot(7)

Similar to Going Reactive with gRPC

Similar to Going Reactive with gRPC(20)

More from Andres Almiray

More from Andres Almiray(20)

Recently uploaded

Recently uploaded(20)

Going Reactive with gRPC