Building Reactive Microservices - SouJava

1. Building Reactive Microservices with Vert.x
Claudio Eduardo de Oliveira

2. About me
Claudio Eduardo de Oliveira
Developer @ Daitan Group
Bacharel em Ciência da Computação
Cursando MBA em Arquitetura de Soluções em
Tecnologia (DeVry/Metrocamp)
Entusiasta Docker / Spring / Vert.x Contatos:
Email: claudioed.oliveira@gmail.com
Linkedin: https://br.linkedin.com/in/claudioedoliveira
Twitter: @claudioed

3. Agenda
● Microservices
○ Definition
○ Patterns
● Reactive Manifesto
○ Reactive Systems
○ Reactive Programming
● Vert.x

4. Definition
The term "Microservice Architecture" has sprung up over the last
few years to describe a particular way of designing software
applications as suites of independently deployable services.
While there is no precise definition of this architectural style,
there are certain common characteristics around organization
around business capability, automated deployment, intelligence in
the endpoints, and decentralized control of languages and data.
microservices
https://martinfowler.com/articles/microservices.html

5. Example microservices
https://cdn.wp.nginx.com/wp-content/uploads/2016/04/Richardson-microservices-part1-2_microservices-architecture.png

6. Microservices Patterns
● Circuit Breakers
● Service Discovery
microservices

7. Circuit Breaker microservices
“The basic idea behind the circuit breaker is very simple. You
wrap a protected function call in a circuit breaker object,
which monitors for failures”
https://martinfowler.com/bliki/CircuitBreaker.html

8. Service Discovery microservices
Service discovery is the automatic detection of devices and
services offered by these devices on a computer network
https://en.wikipedia.org/wiki/Service_discovery

9. reactiveReactive Manifesto
http://www.reactivemanifesto.org/

10. Reactive Systems
as defined by the Reactive Manifesto—is a set of
architectural design principles for building modern
systems that are well prepared to meet the
increasing demands that applications face today.
https://www.lightbend.com/reactive-programming-versus-reactive-systems
reactive

11. Reactive Programming
In computing, reactive programming is an
asynchronous programming paradigm
concerned with data streams and the
propagation of change
https://en.wikipedia.org/wiki/Reactive_programming
reactive

12. We will talk about Reactive Systems….
reactive

13. Some JVM players reactive

16. Definition
Eclipse Vert.x is a toolkit for building
reactive applications on the JVM
vert.x
http://vertx.io/

17. Highlights
● Non-Blocking (vert.x
core)
● Polyglot
● Event Bus
● General purpose
● Unopinionated
vert.x

18. NO Black Magic - Spring Way vert.x
@SpringBootApplication
@EnableHystrix
public class MusicRecommendationApplication {
public static void main(String[] args) {
SpringApplication
.run(MusicRecommendationApplication.class, args);
}
}

19. NO Black Magic vert.x
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(excludeFilters = {
@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
public @interface SpringBootApplication {
…….}

20. Vert.x Way vert.x
public class EventLoopVerticle extends AbstractVerticle {
private static final Logger LOGGER = LoggerFactory.getLogger(EventLoopVerticle.class);
public void start() {
final Router router = Router.router(vertx);
router.get("/test").handler(req -> {
LOGGER.info(" receiving request");
req.response()
.putHeader("content-type","text/plain")
.end(NormalProcess.process());
});
vertx.createHttpServer().requestHandler(router::accept).listen(8080);
}
}

21. Dependencies - Maven vert.x
<dependency>
<groupId>io.vertx</groupId>
<artifactId>vertx-dependencies</artifactId>
<version>${vertx.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>io.vertx</groupId>
<artifactId>vertx-core</artifactId>
</dependency>
<dependency>
<groupId>io.vertx</groupId>
<artifactId>vertx-web</artifactId>
</dependency>

22. Core Concepts
Verticle
vert.x
Event Bus

23. Verticle vert.x
● Small Vert Unit
● Regular Verticle
● Worker Verticle
● Multi Threaded Worker
● Automatic node discovery

24. Reactor Pattern
The reactor pattern is one implementation technique of event-
driven architecture. In simple terms, it uses a single threaded
event loop blocking on resource-emitting events and
dispatches them to corresponding handlers and callbacks
vert.x
https://dzone.com/articles/understanding-reactor-pattern-thread-based-and-eve

25. Regular Verticle - Event Loop vert.x

26. Reactor Pattern - Vert.x vert.x

27. Demo vert.x

28. Regular Verticle
● Golden Rule - Don’t block me!
● Event Loop (more than one)
● Multi Reactor Pattern
● High throughput (i.e http)
vert.x

29. public class EventLoopVerticle extends AbstractVerticle {
public void start() {
final Router router = Router.router(vertx);
router.get("/test").handler(req -> {
req.response()
.putHeader("content-type","text/plain")
.end(NormalProcess.process());
});
vertx.createHttpServer().requestHandler(router::accept).listen(8080);
}
}
Regular Verticle - Example vert.x

30. Don't do this !!!! vert.x
public class EventLoopBlockerVerticle extends AbstractVerticle {
public void start() {
final Router router = Router.router(vertx);
router.get("/test").handler(req -> {
LongRunningProcess.longProcess();
final String date = LocalDateTime.now().toString();
req.response()
.putHeader("content-type","text/plain")
.end(String.format("TDC 2017 %s", date));
});
vertx.createHttpServer().requestHandler(router::accept).listen(8081);
}
}

31. Worker Verticle
● Vert.x worker thread pool
● Execute blocking code
● They are never executed by more than one thread
● Background tasks
vert.x

32. Worker Verticle vert.x
public class EventLoopBusVerticle extends AbstractVerticle {
public void start() {
this.vertx.deployVerticle(new BusVerticle(),
new DeploymentOptions().setWorker(true));
this.vertx.deployVerticle(new RequestResourceVerticle());
}
}

33. Multi Threaded Verticle
● Based on worker verticle
● Can be executed concurrently by different threads
● Hard to code because you need to maintain states
between verticles
● Specific needs
vert.x

34. Event Bus
● Nervous system of Vert.x
● Publish / Subscribe
● Point to Point
● Request Response
● Can be distributed
vert.x

35. Event Bus vert.x
http://allegro.tech/2015/11/real-time-web-application-with-websockets-and-vert-x.html

36. Event Bus vert.x
public class RequestResourceVerticle extends AbstractVerticle {
private static final Logger LOGGER = LoggerFactory.getLogger(BusVerticle.class);
public void start() {
final EventBus eventBus = vertx.eventBus();
final Router router = Router.router(vertx);
router.get("/test").handler(req -> {
eventBus.send("data-stream", new JsonObject(), responseBus -> {
if (responseBus.succeeded()) {
req.response()
.putHeader("content-type", "text/plain")
.end(responseBus.result().body().toString());
}
});
});
vertx.createHttpServer().requestHandler(router::accept).listen(8082);
}
}

37. Service Discovery
This component provides an infrastructure to publish and
discover various resources, such as service proxies, HTTP
endpoints, data sources…​
vert.x
http://vertx.io/docs/vertx-service-discovery/java/

38. Service Discovery
Service provider
Publish / Unpublish service record
Update the status of a service
vert.x
http://vertx.io/docs/vertx-service-discovery/java/

39. Service Discovery
Service consumer
Lookup service
Bind to a selected service
Release the service
Listen for arrival and departure
vert.x
http://vertx.io/docs/vertx-service-discovery/java/

40. Service Discovery - Backend vert.x
final ServiceDiscoveryOptions serviceDiscoveryOptions = new ServiceDiscoveryOptions()
.setBackendConfiguration(
new JsonObject()
.put("host", "127.0.0.1")
.put("port", "6379")
);
ServiceDiscovery sd = ServiceDiscovery.create(vertx,serviceDiscoveryOptions);

41. Service Discovery - Publish vert.x
vertx.createHttpServer().requestHandler(router::accept)
.rxListen(8083)
.flatMap(httpServer -> discovery
.rxPublish(HttpEndpoint.createRecord("product", "localhost", 8083, "/")))
.subscribe(rec -> LOGGER.info("Product Service is published"));

42. Service Discovery - Consumer vert.x
final ServiceDiscoveryOptions serviceDiscoveryOptions = new ServiceDiscoveryOptions()
.setBackendConfiguration(
new JsonObject()
.put("host", "127.0.0.1")
.put("port", "6379")
);
ServiceDiscovery discovery = ServiceDiscovery.create(vertx,serviceDiscoveryOptions);
….
HttpEndpoint.rxGetWebClient(discovery, rec -> rec.getName().endsWith("product"))
.flatMap(client -> client.get("/product/" + id).as(BodyCodec.string()).rxSend())
.subscribe(response -> req.response()
.putHeader("content-type", "application/json")
.end(response.body()));
});

43. Service Discovery
● Consul
● Kubernetes
● Redis
● Docker
vert.x

44. Circuit Breaker vert.x
https://www.oreilly.com/ideas/microservices-antipatterns-and-pitfalls

45. breaker.executeWithFallback(
future -> {
vertx.createHttpClient().getNow(8080, "localhost", "/", response -> {
if (response.statusCode() != 200) {
future.fail("HTTP error");
} else {
response
.exceptionHandler(future::fail)
.bodyHandler(buffer -> {
future.complete(buffer.toString());
});
}
});
}, v -> {
// Executed when the circuit is opened
return "Hello";
})
.setHandler(ar -> {
// Do something with the result
});
Circuit Breaker vert.x

46. Relational Database Integrations
● MySQL
● PostgreSQL
● JDBC
vert.x

47. NoSQL Database Integrations
● Redis
● MongoDB
● Cassandra
● OrientDB
vert.x

48. Messaging
● Kafka
● MQTT
● ZeroMQ
● RabbitMQ
● AMQP 1.0
vert.x

49. vert.xDemo

50. Demo vert.x

52. References
http://vertx.io/docs/guide-for-java-devs/
https://www.oreilly.com/ideas/reactive-programming-vs-reactive-systems
https://dzone.com/articles/understanding-reactor-pattern-thread-based-and-eve
https://developers.redhat.com/promotions/building-reactive-microservices-in-java/
https://github.com/claudioed/travel-helper