BAEL-711 Guide_to_Microservices_using_lagom_framework Changes (#1495)
* BAEL_711_Guide_to_Microservices_using_lagom_framework Changes * BAEL_711_Guide_to_Microservices_using_lagom_framework_v2 * BAEL_711_Guide_to_Microservices_using_lagom-Review Comments
This commit is contained in:
Nikhil Khatwani
pedja4
parent
c73c252924
commit
4daef51161
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greeting-impl/logs/*
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lagom-hello-world/greeting-impl/bin/classes/*
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lagom-hello-world/logs/application.log
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lagom-hello-world/weather-impl/logs/application.log
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Steps to setup from scratch
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1) Create sbt build file "build.sbt"
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2) Create plugins file project/plugins.sbt
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3) Create build properties file project/build.properties
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4) Run sbt command from project root to generate project directories, generated projects at target/lagom-dynamic-projects
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Service Locator project: lagom-internal-meta-project-service-locator
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cassandra project: lagom-internal-meta-project-cassandra
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5) Create folders in all projects to follow maven like directory structure layout for project source code: src/main/java and src/main/java/resources and test folders.
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6) Weather microservice
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a) WeatherService Interface with method:
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weatherStatsForToday()
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b) WeatherServiceImpl to return weatherstats from a random list of weather stats
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7) Greeting Microservice
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GreetingService Interface:
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handleGreetFrom(String user)
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a) Reply back to user with greeting message("Hello") along with weather stats fetched from weather microservice
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b) Update the greeting message("Hello Again") for an existing user.
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8) GreetingEntity: PersistentEntity<GreetingCommand, GreetingEvent, GreetingState>
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a) handles ReceivedGreetingCommand
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b) Stores ReceivedGreetingEvent events to cassandra
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c) Processes ReceivedGreetingEvent to update GreetingState("Hello" to "Hello Again") if required.
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9) Register modules with lagom using application.conf files.
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10) Run project: sbt lagom:runAll
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Sample Run:
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curl http://localhost:9000/api/greeting/Nikhil;
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Hello Nikhil! Today's weather stats: Going to be very humid, Take Water
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curl http://localhost:9000/api/greeting/Nikhil;
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Hello Again Nikhil! Today's weather stats: Going to Rain, Take Umbrella
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organization in ThisBuild := "org.baeldung"
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// the Scala version that will be used for cross-compiled libraries
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scalaVersion in ThisBuild := "2.11.7"
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lagomKafkaEnabled in ThisBuild := false
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lazy val greetingApi = project("greeting-api")
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.settings(
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version := "1.0-SNAPSHOT",
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libraryDependencies ++= Seq(
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lagomJavadslApi
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)
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)
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lazy val greetingImpl = project("greeting-impl")
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.enablePlugins(LagomJava)
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.settings(
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version := "1.0-SNAPSHOT",
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libraryDependencies ++= Seq(
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lagomJavadslPersistenceCassandra
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)
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)
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.dependsOn(greetingApi, weatherApi)
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lazy val weatherApi = project("weather-api")
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.settings(
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version := "1.0-SNAPSHOT",
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libraryDependencies ++= Seq(
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lagomJavadslApi
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)
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)
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lazy val weatherImpl = project("weather-impl")
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.enablePlugins(LagomJava)
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.settings(
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version := "1.0-SNAPSHOT"
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)
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.dependsOn(weatherApi)
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def project(id: String) = Project(id, base = file(id))
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package org.baeldung.lagom.helloworld.greeting.api;
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import static com.lightbend.lagom.javadsl.api.Service.named;
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import static com.lightbend.lagom.javadsl.api.Service.restCall;
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import com.lightbend.lagom.javadsl.api.Descriptor;
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import com.lightbend.lagom.javadsl.api.Service;
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import com.lightbend.lagom.javadsl.api.ServiceCall;
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import com.lightbend.lagom.javadsl.api.transport.Method;
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import akka.NotUsed;
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public interface GreetingService extends Service {
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public ServiceCall<NotUsed, String> handleGreetFrom(String user);
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@Override
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default Descriptor descriptor() {
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return named("greetingservice").withCalls(
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restCall(Method.GET, "/api/greeting/:fromUser", this::handleGreetFrom)
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).withAutoAcl(true);
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}
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}
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play.modules.enabled += org.baeldung.lagom.helloworld.greeting.impl.GreetingServiceModule
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play.modules.enabled += org.baeldung.lagom.helloworld.greeting.impl.GreetingServiceModule
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package org.baeldung.lagom.helloworld.greeting.impl;
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import com.fasterxml.jackson.annotation.JsonCreator;
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import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
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import com.google.common.base.Preconditions;
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import com.lightbend.lagom.javadsl.persistence.PersistentEntity;
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import com.lightbend.lagom.serialization.CompressedJsonable;
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import com.lightbend.lagom.serialization.Jsonable;
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public interface GreetingCommand extends Jsonable {
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@SuppressWarnings("serial")
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@JsonDeserialize
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public final class ReceivedGreetingCommand implements GreetingCommand,
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CompressedJsonable, PersistentEntity.ReplyType<String> {
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private final String fromUser;
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@JsonCreator
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public ReceivedGreetingCommand(String fromUser) {
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this.fromUser = Preconditions.checkNotNull(fromUser, "fromUser");
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}
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public String getFromUser() {
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return fromUser;
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}
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}
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}
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package org.baeldung.lagom.helloworld.greeting.impl;
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import java.util.Optional;
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import org.baeldung.lagom.helloworld.greeting.impl.GreetingCommand.ReceivedGreetingCommand;
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import org.baeldung.lagom.helloworld.greeting.impl.GreetingEvent.ReceivedGreetingEvent;
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import com.lightbend.lagom.javadsl.persistence.PersistentEntity;
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public class GreetingEntity extends PersistentEntity<GreetingCommand,
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GreetingEvent, GreetingState> {
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@Override
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public Behavior initialBehavior(Optional<GreetingState> snapshotState) {
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BehaviorBuilder b = newBehaviorBuilder(new GreetingState("Hello "));
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b.setCommandHandler(ReceivedGreetingCommand.class,
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(cmd, ctx) -> {
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String fromUser = cmd.getFromUser();
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String currentGreeting = state().getMessage();
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return ctx.thenPersist(
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new ReceivedGreetingEvent(fromUser),
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evt -> ctx.reply(currentGreeting + fromUser + "!"));
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});
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b.setEventHandler(ReceivedGreetingEvent.class,
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// We simply update the current state
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evt -> state().withMessage("Hello Again "));
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return b.build();
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}
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}
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package org.baeldung.lagom.helloworld.greeting.impl;
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import com.fasterxml.jackson.annotation.JsonCreator;
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import com.lightbend.lagom.serialization.Jsonable;
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public interface GreetingEvent extends Jsonable {
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class ReceivedGreetingEvent implements GreetingEvent {
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private final String fromUser;
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@JsonCreator
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public ReceivedGreetingEvent(String fromUser) {
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this.fromUser = fromUser;
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}
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public String getFromUser() {
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return fromUser;
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}
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}
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}
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package org.baeldung.lagom.helloworld.greeting.impl;
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import java.util.concurrent.CompletableFuture;
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import java.util.concurrent.ExecutionException;
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import org.baeldung.lagom.helloworld.greeting.api.GreetingService;
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import org.baeldung.lagom.helloworld.greeting.impl.GreetingCommand.ReceivedGreetingCommand;
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import org.baeldung.lagom.helloworld.weather.api.WeatherService;
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import org.baeldung.lagom.helloworld.weather.api.WeatherStats;
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import com.google.inject.Inject;
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import com.lightbend.lagom.javadsl.api.ServiceCall;
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import com.lightbend.lagom.javadsl.persistence.PersistentEntityRef;
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import com.lightbend.lagom.javadsl.persistence.PersistentEntityRegistry;
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import akka.NotUsed;
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public class GreetingServiceImpl implements GreetingService {
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private final PersistentEntityRegistry persistentEntityRegistry;
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private final WeatherService weatherService;
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@Inject
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public GreetingServiceImpl(PersistentEntityRegistry persistentEntityRegistry, WeatherService weatherService) {
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this.persistentEntityRegistry = persistentEntityRegistry;
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this.weatherService = weatherService;
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persistentEntityRegistry.register(GreetingEntity.class);
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}
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@Override
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public ServiceCall<NotUsed, String> handleGreetFrom(String user) {
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return request -> {
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// Look up the hello world entity for the given ID.
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PersistentEntityRef<GreetingCommand> ref = persistentEntityRegistry.refFor(GreetingEntity.class, user);
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CompletableFuture<String> greetingResponse = ref.ask(new ReceivedGreetingCommand(user))
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.toCompletableFuture();
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CompletableFuture<WeatherStats> todaysWeatherInfo =
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(CompletableFuture<WeatherStats>) weatherService.weatherStatsForToday().invoke();
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try {
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return CompletableFuture.completedFuture(greetingResponse.get() +
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" Today's weather stats: " + todaysWeatherInfo.get().getMessage());
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} catch (InterruptedException | ExecutionException e) {
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return CompletableFuture.completedFuture("Sorry Some Error at our end, working on it");
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}
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};
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}
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}
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package org.baeldung.lagom.helloworld.greeting.impl;
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import org.baeldung.lagom.helloworld.greeting.api.GreetingService;
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import org.baeldung.lagom.helloworld.weather.api.WeatherService;
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import com.google.inject.AbstractModule;
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import com.lightbend.lagom.javadsl.server.ServiceGuiceSupport;
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/**
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* The module that binds the GreetingService so that it can be served.
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*/
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public class GreetingServiceModule extends AbstractModule implements ServiceGuiceSupport {
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@Override
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protected void configure() {
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bindServices(serviceBinding(GreetingService.class, GreetingServiceImpl.class));
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bindClient(WeatherService.class);
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}
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}
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package org.baeldung.lagom.helloworld.greeting.impl;
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import com.fasterxml.jackson.annotation.JsonCreator;
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import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
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@JsonDeserialize
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public class GreetingState {
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private final String message;
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@JsonCreator
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public GreetingState(String message) {
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this.message = message;
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}
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GreetingState withMessage(String message) {
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return new GreetingState(message);
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}
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public String getMessage() {
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return message;
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}
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}
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play.modules.enabled += org.baeldung.lagom.helloworld.greeting.impl.GreetingServiceModule
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sbt.version=0.13.11
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addSbtPlugin("com.lightbend.lagom" % "lagom-sbt-plugin" % "1.3.1")
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addSbtPlugin("com.typesafe.sbteclipse" % "sbteclipse-plugin" % "3.0.0")
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package org.baeldung.lagom.helloworld.weather.api;
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import static com.lightbend.lagom.javadsl.api.Service.named;
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import static com.lightbend.lagom.javadsl.api.Service.*;
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import com.lightbend.lagom.javadsl.api.Descriptor;
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import com.lightbend.lagom.javadsl.api.Service;
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import com.lightbend.lagom.javadsl.api.ServiceCall;
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import com.lightbend.lagom.javadsl.api.transport.Method;
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import akka.NotUsed;
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/**
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* WeatherService Interface.
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*/
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public interface WeatherService extends Service {
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// Fetch Today's Weather Stats service call
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public ServiceCall<NotUsed, WeatherStats> weatherStatsForToday();
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@Override
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default Descriptor descriptor() {
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return named("weatherservice").withCalls(
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restCall(Method.GET, "/api/weather", this::weatherStatsForToday)
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).withAutoAcl(true);
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}
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}
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package org.baeldung.lagom.helloworld.weather.api;
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import java.util.Arrays;
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import java.util.Collections;
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import java.util.List;
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import java.util.Random;
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public enum WeatherStats {
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STATS_RAINY("Going to Rain, Take Umbrella"), STATS_HUMID("Going to be very humid, Take Water");
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private final String message;
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private static final List<WeatherStats> VALUES = Collections.unmodifiableList(Arrays.asList(values()));
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private static final int SIZE = VALUES.size();
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private static final Random RANDOM = new Random();
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WeatherStats(String msg) {
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this.message = msg;
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}
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public static WeatherStats forToday() {
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return VALUES.get(RANDOM.nextInt(SIZE));
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}
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public String getMessage() {
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return message;
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}
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}
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play.modules.enabled += org.baeldung.lagom.helloworld.weather.impl.WeatherServiceModule
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package org.baeldung.lagom.helloworld.weather.impl;
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import java.util.concurrent.CompletableFuture;
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import org.baeldung.lagom.helloworld.weather.api.WeatherService;
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import org.baeldung.lagom.helloworld.weather.api.WeatherStats;
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import com.lightbend.lagom.javadsl.api.ServiceCall;
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import akka.NotUsed;
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public class WeatherServiceImpl implements WeatherService {
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@Override
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public ServiceCall<NotUsed, WeatherStats> weatherStatsForToday() {
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return (req) -> CompletableFuture.completedFuture(WeatherStats.forToday());
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}
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}
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package org.baeldung.lagom.helloworld.weather.impl;
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import org.baeldung.lagom.helloworld.weather.api.WeatherService;
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import com.google.inject.AbstractModule;
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import com.lightbend.lagom.javadsl.server.ServiceGuiceSupport;
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/**
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* The module that binds the GreetingService so that it can be served.
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*/
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public class WeatherServiceModule extends AbstractModule implements ServiceGuiceSupport {
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@Override
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protected void configure() {
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bindServices(serviceBinding(WeatherService.class, WeatherServiceImpl.class));
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}
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}
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play.modules.enabled += org.baeldung.lagom.helloworld.weather.impl.WeatherServiceModule
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