=per #15429 Rewrite persistence documentation and samples for 2.3.4 changes
(cherry picked from commit 02351e32f110a8c4a249f0f3f84bae5898d1a836) Conflicts: akka-samples/akka-sample-persistence-java-lambda/tutorial/index.html akka-samples/akka-sample-persistence-java/tutorial/index.html akka-samples/akka-sample-persistence-scala/build.sbt akka-samples/akka-sample-persistence-scala/src/main/scala/sample/persistence/ConversationRecoveryExample.scala akka-samples/akka-sample-persistence-scala/src/main/scala/sample/persistence/PersistentActorExample.scala akka-samples/akka-sample-persistence-scala/src/main/scala/sample/persistence/ProcessorChannelExample.scala akka-samples/akka-sample-persistence-scala/src/main/scala/sample/persistence/ProcessorChannelRemoteExample.scala akka-samples/akka-sample-persistence-scala/src/main/scala/sample/persistence/SnapshotExample.scala akka-samples/akka-sample-persistence-scala/src/main/scala/sample/persistence/StreamExample.scala akka-samples/akka-sample-persistence-scala/tutorial/index.html
This commit is contained in:
Patrik Nordwall
parent
062d304b73
commit
d6ffdf521c
35 changed files with 1091 additions and 2276 deletions
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@ -136,27 +136,31 @@ public class LambdaPersistenceDocTest {
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}
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//#recovery-completed
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class MyProcessor5 extends AbstractProcessor {
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public MyProcessor5() {
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receive(ReceiveBuilder.
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match(RecoveryCompleted.class, r -> {
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recoveryCompleted();
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getContext().become(active);
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}).
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build()
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);
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class MyPersistentActor5 extends AbstractPersistentActor {
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@Override public PartialFunction<Object, BoxedUnit> receiveRecover() {
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return ReceiveBuilder.
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match(String.class, this::handleEvent).build();
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}
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@Override public PartialFunction<Object, BoxedUnit> receiveCommand() {
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return ReceiveBuilder.
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match(RecoveryCompleted.class, r -> {
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recoveryCompleted();
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}).
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match(String.class, s -> s.equals("cmd"),
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s -> persist("evt", this::handleEvent)).build();
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}
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private void recoveryCompleted() {
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// perform init after recovery, before any other messages
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// ...
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}
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PartialFunction<Object, BoxedUnit> active =
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ReceiveBuilder.
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match(Persistent.class, message -> {/* ... */}).
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build();
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private void handleEvent(String event) {
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// update state
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// ...
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}
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}
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//#recovery-completed
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@ -1,76 +0,0 @@
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/**
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* Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
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*/
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package sample.persistence;
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import akka.actor.ActorRef;
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import akka.actor.ActorSystem;
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import akka.actor.Props;
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import akka.japi.pf.ReceiveBuilder;
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import akka.persistence.*;
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import scala.PartialFunction;
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import scala.runtime.BoxedUnit;
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public class ConversationRecoveryExample {
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public static String PING = "PING";
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public static String PONG = "PONG";
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public static class Ping extends AbstractProcessor {
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final ActorRef pongChannel = context().actorOf(Channel.props(), "pongChannel");
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int counter = 0;
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public Ping() {
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receive(ReceiveBuilder.
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match(ConfirmablePersistent.class, cp -> cp.payload().equals(PING), cp -> {
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counter += 1;
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System.out.println(String.format("received ping %d times", counter));
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cp.confirm();
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if (!recoveryRunning()) {
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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pongChannel.tell(Deliver.create(cp.withPayload(PONG), sender().path()), self());
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}).
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match(String.class,
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s -> s.equals("init"),
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s -> pongChannel.tell(Deliver.create(Persistent.create(PONG), sender().path()), self())).build()
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);
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}
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}
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public static class Pong extends AbstractProcessor {
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private final ActorRef pingChannel = context().actorOf(Channel.props(), "pingChannel");
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private int counter = 0;
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public Pong() {
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receive(ReceiveBuilder.
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match(ConfirmablePersistent.class, cp -> cp.payload().equals(PONG), cp -> {
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counter += 1;
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System.out.println(String.format("received pong %d times", counter));
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cp.confirm();
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if (!recoveryRunning()) {
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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pingChannel.tell(Deliver.create(cp.withPayload(PING), sender().path()), self());
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}).build()
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);
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}
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}
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public static void main(String... args) throws Exception {
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final ActorSystem system = ActorSystem.create("example");
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final ActorRef ping = system.actorOf(Props.create(Ping.class), "ping");
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final ActorRef pong = system.actorOf(Props.create(Pong.class), "pong");
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ping.tell("init", pong);
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}
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}
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@ -73,43 +73,46 @@ class ExampleState implements Serializable {
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}
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}
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class ExampleProcessor extends AbstractPersistentActor {
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class ExamplePersistentActor extends AbstractPersistentActor {
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private ExampleState state = new ExampleState();
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public int getNumEvents() {
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return state.size();
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}
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@Override
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public PartialFunction<Object, BoxedUnit> receiveRecover() {
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@Override
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public PartialFunction<Object, BoxedUnit> receiveRecover() {
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return ReceiveBuilder.
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match(Evt.class, state::update).
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match(SnapshotOffer.class, ss -> state = (ExampleState) ss.snapshot()).build();
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}
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@Override
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public PartialFunction<Object, BoxedUnit> receiveCommand() {
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return ReceiveBuilder.match(Cmd.class, c -> {
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final String data = c.getData();
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final Evt evt1 = new Evt(data + "-" + getNumEvents());
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final Evt evt2 = new Evt(data + "-" + (getNumEvents() + 1));
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persist(asList(evt1, evt2), (Evt evt) -> {
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state.update(evt);
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if (evt.equals(evt2)) {
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context().system().eventStream().publish(evt);
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}
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});
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}).
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@Override
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public PartialFunction<Object, BoxedUnit> receiveCommand() {
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return ReceiveBuilder.
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match(Cmd.class, c -> {
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final String data = c.getData();
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final Evt evt1 = new Evt(data + "-" + getNumEvents());
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final Evt evt2 = new Evt(data + "-" + (getNumEvents() + 1));
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persist(asList(evt1, evt2), (Evt evt) -> {
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state.update(evt);
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if (evt.equals(evt2)) {
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context().system().eventStream().publish(evt);
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}
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});
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}).
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match(String.class, s -> s.equals("snap"), s -> saveSnapshot(state.copy())).
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match(String.class, s -> s.equals("print"), s -> System.out.println(state)).build();
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match(String.class, s -> s.equals("print"), s -> System.out.println(state)).
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build();
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}
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}
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//#persistent-actor-example
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public class PersistentActorExample {
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public static void main(String... args) throws Exception {
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final ActorSystem system = ActorSystem.create("example");
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final ActorRef processor = system.actorOf(Props.create(ExampleProcessor.class), "processor-4-java8");
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final ActorRef processor = system.actorOf(Props.create(ExamplePersistentActor.class), "processor-4-java8");
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processor.tell(new Cmd("foo"), null);
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processor.tell(new Cmd("baz"), null);
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processor.tell(new Cmd("bar"), null);
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@ -0,0 +1,74 @@
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/**
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* Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
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*/
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package sample.persistence;
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import akka.actor.ActorRef;
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import akka.actor.ActorSystem;
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import akka.actor.Props;
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import akka.japi.pf.ReceiveBuilder;
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import akka.persistence.AbstractPersistentActor;
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import scala.PartialFunction;
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import scala.runtime.BoxedUnit;
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import java.util.ArrayList;
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public class PersistentActorFailureExample {
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public static class ExamplePersistentActor extends AbstractPersistentActor {
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private ArrayList<Object> received = new ArrayList<Object>();
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@Override
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public PartialFunction<Object, BoxedUnit> receiveCommand() {
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return ReceiveBuilder.
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match(String.class, s -> s.equals("boom"), s -> {throw new RuntimeException("boom");}).
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match(String.class, s -> s.equals("print"), s -> System.out.println("received " + received)).
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match(String.class, s -> {
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persist(s, evt -> {
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received.add(evt);
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});
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}).
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build();
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}
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@Override
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public PartialFunction<Object, BoxedUnit> receiveRecover() {
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return ReceiveBuilder.
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match(String.class, s -> received.add(s)).
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build();
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}
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}
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public static void main(String... args) throws Exception {
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final ActorSystem system = ActorSystem.create("example");
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final ActorRef persistentActor = system.actorOf(Props.create(ExamplePersistentActor.class), "persistentActor-2");
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persistentActor.tell("a", null);
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persistentActor.tell("print", null);
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persistentActor.tell("boom", null);
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persistentActor.tell("print", null);
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persistentActor.tell("b", null);
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persistentActor.tell("print", null);
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persistentActor.tell("c", null);
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persistentActor.tell("print", null);
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// Will print in a first run (i.e. with empty journal):
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// received [a]
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// received [a, b]
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// received [a, b, c]
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// Will print in a second run:
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// received [a, b, c, a]
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// received [a, b, c, a, b]
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// received [a, b, c, a, b, c]
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// etc ...
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Thread.sleep(1000);
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system.shutdown();
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}
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}
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@ -14,11 +14,11 @@ import scala.PartialFunction;
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import scala.runtime.BoxedUnit;
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public class ProcessorChannelExample {
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public static class ExampleProcessor extends AbstractProcessor {
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public static class ExamplePersistentActor extends AbstractProcessor {
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private ActorRef destination;
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private ActorRef channel;
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public ExampleProcessor(ActorRef destination) {
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public ExamplePersistentActor(ActorRef destination) {
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this.destination = destination;
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this.channel = context().actorOf(Channel.props(), "channel");
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@ -47,7 +47,7 @@ public class ProcessorChannelExample {
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public static void main(String... args) throws Exception {
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final ActorSystem system = ActorSystem.create("example");
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final ActorRef destination = system.actorOf(Props.create(ExampleDestination.class));
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final ActorRef processor = system.actorOf(Props.create(ExampleProcessor.class, destination), "processor-1");
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final ActorRef processor = system.actorOf(Props.create(ExamplePersistentActor.class, destination), "processor-1");
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processor.tell(Persistent.create("a"), null);
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processor.tell(Persistent.create("b"), null);
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@ -1,71 +0,0 @@
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/**
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* Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
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*/
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package sample.persistence;
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import akka.actor.ActorRef;
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import akka.actor.ActorSystem;
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import akka.actor.Props;
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import akka.japi.pf.ReceiveBuilder;
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import akka.persistence.AbstractProcessor;
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import akka.persistence.Persistent;
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import scala.Option;
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import java.util.ArrayList;
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public class ProcessorFailureExample {
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public static class ExampleProcessor extends AbstractProcessor {
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private ArrayList<Object> received = new ArrayList<Object>();
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public ExampleProcessor() {
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receive(ReceiveBuilder.
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match(Persistent.class, p -> p.payload().equals("boom"), p -> {throw new RuntimeException("boom");}).
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match(Persistent.class, p -> !p.payload().equals("boom"), p -> received.add(p.payload())).
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match(String.class, s -> s.equals("boom"), s -> {throw new RuntimeException("boom");}).
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match(String.class, s -> s.equals("print"), s -> System.out.println("received " + received)).build()
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);
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}
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@Override
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public void preRestart(Throwable reason, Option<Object> message) {
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if (message.isDefined() && message.get() instanceof Persistent) {
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deleteMessage(((Persistent) message.get()).sequenceNr(), false);
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}
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super.preRestart(reason, message);
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}
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}
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public static void main(String... args) throws Exception {
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final ActorSystem system = ActorSystem.create("example");
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final ActorRef processor = system.actorOf(Props.create(ExampleProcessor.class), "processor-2");
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processor.tell(Persistent.create("a"), null);
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processor.tell("print", null);
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processor.tell("boom", null);
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processor.tell("print", null);
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processor.tell(Persistent.create("b"), null);
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processor.tell("print", null);
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processor.tell(Persistent.create("boom"), null);
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processor.tell("print", null);
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processor.tell(Persistent.create("c"), null);
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processor.tell("print", null);
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// Will print in a first run (i.e. with empty journal):
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// received [a]
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// received [a, b]
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// received [a, b, c]
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// Will print in a second run:
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// received [a, b, c, a]
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// received [a, b, c, a, b]
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// received [a, b, c, a, b, c]
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// etc ...
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Thread.sleep(1000);
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system.shutdown();
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}
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}
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@ -8,7 +8,7 @@ import akka.actor.ActorRef;
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import akka.actor.ActorSystem;
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import akka.actor.Props;
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import akka.japi.pf.ReceiveBuilder;
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import akka.persistence.AbstractProcessor;
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import akka.persistence.AbstractPersistentActor;
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import akka.persistence.Persistent;
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import akka.persistence.SnapshotOffer;
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import scala.PartialFunction;
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@ -43,36 +43,47 @@ public class SnapshotExample {
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}
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}
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public static class ExampleProcessor extends AbstractProcessor {
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public static class ExamplePersistentActor extends AbstractPersistentActor {
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private ExampleState state = new ExampleState();
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public ExampleProcessor() {
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receive(ReceiveBuilder.
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match(Persistent.class, p -> state.update(String.format("%s-%d", p.payload(), p.sequenceNr()))).
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match(SnapshotOffer.class, s -> {
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ExampleState exState = (ExampleState) s.snapshot();
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System.out.println("offered state = " + exState);
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state = exState;
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}).
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@Override
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public PartialFunction<Object, BoxedUnit> receiveCommand() {
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return ReceiveBuilder.
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match(String.class, s -> s.equals("print"), s -> System.out.println("current state = " + state)).
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match(String.class, s -> s.equals("snap"), s ->
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// IMPORTANT: create a copy of snapshot
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// because ExampleState is mutable !!!
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saveSnapshot(state.copy())).build()
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);
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saveSnapshot(state.copy())).
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match(String.class, s -> {
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persist(s, evt -> {
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state.update(evt);
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});
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}).
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build();
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}
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@Override
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public PartialFunction<Object, BoxedUnit> receiveRecover() {
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return ReceiveBuilder.
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match(String.class, evt -> state.update(evt)).
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match(SnapshotOffer.class, ss -> {
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System.out.println("offered state = " + ss);
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state = (ExampleState) ss.snapshot();
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}).
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build();
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}
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}
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public static void main(String... args) throws Exception {
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final ActorSystem system = ActorSystem.create("example");
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final ActorRef processor = system.actorOf(Props.create(ExampleProcessor.class), "processor-3-java");
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final ActorRef persistentActor = system.actorOf(Props.create(ExamplePersistentActor.class), "persistentActor-3-java");
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processor.tell(Persistent.create("a"), null);
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processor.tell(Persistent.create("b"), null);
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processor.tell("snap", null);
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processor.tell(Persistent.create("c"), null);
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processor.tell(Persistent.create("d"), null);
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processor.tell("print", null);
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persistentActor.tell("a", null);
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persistentActor.tell("b", null);
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persistentActor.tell("snap", null);
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persistentActor.tell("c", null);
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persistentActor.tell("d", null);
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persistentActor.tell("print", null);
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Thread.sleep(1000);
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system.shutdown();
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@ -17,25 +17,35 @@ import scala.runtime.BoxedUnit;
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import java.util.concurrent.TimeUnit;
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public class ViewExample {
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public static class ExampleProcessor extends AbstractProcessor {
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public static class ExamplePersistentActor extends AbstractPersistentActor {
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private int count = 1;
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@Override
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public String processorId() {
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return "processor-5";
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public String persistenceId() {
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return "persistentActor-5";
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}
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public ExampleProcessor() {
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receive(ReceiveBuilder.
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match(Persistent.class,
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p -> System.out.println(String.format("processor received %s (sequence nr = %d)",
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p.payload(),
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p.sequenceNr()))).build()
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);
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@Override
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public PartialFunction<Object, BoxedUnit> receiveCommand() {
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return ReceiveBuilder.
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match(String.class, s -> {
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System.out.println(String.format("persistentActor received %s (nr = %d)", s, count));
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persist(s + count, evt -> {
|
||||
count += 1;
|
||||
});
|
||||
}).
|
||||
build();
|
||||
}
|
||||
|
||||
@Override
|
||||
public PartialFunction<Object, BoxedUnit> receiveRecover() {
|
||||
return ReceiveBuilder.
|
||||
match(String.class, s -> count += 1).
|
||||
build();
|
||||
}
|
||||
}
|
||||
|
||||
public static class ExampleView extends AbstractView {
|
||||
private final ActorRef destination = context().actorOf(Props.create(ExampleDestination.class));
|
||||
private final ActorRef channel = context().actorOf(Channel.props("channel"));
|
||||
|
||||
private int numReplicated = 0;
|
||||
|
||||
|
|
@ -46,19 +56,16 @@ public class ViewExample {
|
|||
|
||||
@Override
|
||||
public String persistenceId() {
|
||||
return "processor-5";
|
||||
return "persistentActor-5";
|
||||
}
|
||||
|
||||
public ExampleView() {
|
||||
receive(ReceiveBuilder.
|
||||
match(Persistent.class, p -> {
|
||||
numReplicated += 1;
|
||||
System.out.println(String.format("view received %s (sequence nr = %d, num replicated = %d)",
|
||||
System.out.println(String.format("view received %s (num replicated = %d)",
|
||||
p.payload(),
|
||||
p.sequenceNr(),
|
||||
numReplicated));
|
||||
channel.tell(Deliver.create(p.withPayload("replicated-" + p.payload()), destination.path()),
|
||||
self());
|
||||
}).
|
||||
match(SnapshotOffer.class, so -> {
|
||||
numReplicated = (Integer) so.snapshot();
|
||||
|
|
@ -71,30 +78,16 @@ public class ViewExample {
|
|||
}
|
||||
}
|
||||
|
||||
public static class ExampleDestination extends AbstractActor {
|
||||
|
||||
public ExampleDestination() {
|
||||
receive(ReceiveBuilder.
|
||||
match(ConfirmablePersistent.class, cp -> {
|
||||
System.out.println(String.format("destination received %s (sequence nr = %s)",
|
||||
cp.payload(),
|
||||
cp.sequenceNr()));
|
||||
cp.confirm();
|
||||
}).build()
|
||||
);
|
||||
}
|
||||
}
|
||||
|
||||
public static void main(String... args) throws Exception {
|
||||
final ActorSystem system = ActorSystem.create("example");
|
||||
final ActorRef processor = system.actorOf(Props.create(ExampleProcessor.class));
|
||||
final ActorRef persistentActor = system.actorOf(Props.create(ExamplePersistentActor.class));
|
||||
final ActorRef view = system.actorOf(Props.create(ExampleView.class));
|
||||
|
||||
system.scheduler()
|
||||
.schedule(Duration.Zero(),
|
||||
Duration.create(2, TimeUnit.SECONDS),
|
||||
processor,
|
||||
Persistent.create("scheduled"),
|
||||
persistentActor,
|
||||
"scheduled",
|
||||
system.dispatcher(),
|
||||
null);
|
||||
system.scheduler()
|
||||
|
|
|
|||
|
|
@ -12,12 +12,10 @@ This tutorial contains examples that illustrate a subset of
|
|||
<a href="http://doc.akka.io/docs/akka/2.4-SNAPSHOT/java/lambda-persistence.html" target="_blank">Akka Persistence</a> features.
|
||||
</p>
|
||||
<ul>
|
||||
<li>Processors and channels</li>
|
||||
<li>Processsor snapshots</li>
|
||||
<li>Eventsourced processors</li>
|
||||
<li>Processor failure handling</li>
|
||||
<li>Processor views</li>
|
||||
<li>Processor conversation recovery</li>
|
||||
<li>persistent actor</li>
|
||||
<li>persistent actor snapshots</li>
|
||||
<li>persistent actor recovery</li>
|
||||
<li>persistent actor views</li>
|
||||
</ul>
|
||||
|
||||
<p>
|
||||
|
|
@ -27,47 +25,13 @@ Custom storage locations for the journal and snapshots can be defined in
|
|||
</div>
|
||||
|
||||
<div>
|
||||
<h2>Processors and channels</h2>
|
||||
<h2>Persistent actor</h2>
|
||||
<p>
|
||||
<a href="#code/src/main/java/sample/persistence/ProcessorChannelExample.java" class="shortcut">ProcessorChannelExample.java</a>
|
||||
defines an <code>ExampleProcessor</code> and an <code>ExampleDestination</code>. The processor sends messages to a
|
||||
destination via a channel. The destination confirms the delivery of these messages so that replayed messages aren't
|
||||
redundantly delivered to the destination. Repeated runs of the application demonstrates that the processor receives
|
||||
both replayed and new messages whereas the channel only receives new messages, sent by the application. The processor
|
||||
also receives replies from the destination, demonstrating that a channel preserves sender references.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and run the application main class
|
||||
<b><code>sample.persistence.ProcessorChannelExample</code></b> several times.
|
||||
</p>
|
||||
</div>
|
||||
|
||||
<div>
|
||||
<h2>Processor snapshots</h2>
|
||||
<p>
|
||||
<a href="#code/src/main/java/sample/persistence/SnapshotExample.java" class="shortcut">SnapshotExample.java</a>
|
||||
demonstrates how processors can take snapshots of application state and recover from previously stored snapshots.
|
||||
Snapshots are offered to processors at the beginning of recovery, before any messages (younger than the snapshot)
|
||||
are replayed.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and run the application main class
|
||||
<b><code>sample.persistence.SnapshotExample</code></b> several times. With every run, the state offered by the
|
||||
most recent snapshot is printed to <code>stdout</code>, followed by the updated state after sending new persistent
|
||||
messages to the processor.
|
||||
</p>
|
||||
</div>
|
||||
|
||||
<div>
|
||||
<h2>Eventsourced processors</h2>
|
||||
<p>
|
||||
<a href="#code/src/main/java/sample/persistence/EventsourcedExample.java" class="shortcut">EventsourcedExample.java</a>
|
||||
is described in detail in the <a href="http://doc.akka.io/docs/akka/2.4-SNAPSHOT/java/lambda-persistence.html#event-sourcing" target="_blank">Event sourcing</a>
|
||||
section of the user documentation. With every application run, the <code>ExampleProcessor</code> is recovered from
|
||||
<a href="#code/src/main/java/sample/persistence/PersistentActorExample.java" class="shortcut">PersistentActorExample.java</a>
|
||||
is described in detail in the <a href="http://doc.akka.io/docs/akka/2.3-SNAPSHOT/java/lambda-persistence.html#event-sourcing-java-lambda" target="_blank">Event sourcing</a>
|
||||
section of the user documentation. With every application run, the <code>ExamplePersistentActor</code> is recovered from
|
||||
events stored in previous application runs, processes new commands, stores new events and snapshots and prints the
|
||||
current processor state to <code>stdout</code>.
|
||||
current persistent actor state to <code>stdout</code>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
|
|
@ -77,60 +41,48 @@ To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and
|
|||
</div>
|
||||
|
||||
<div>
|
||||
<h2>Processor failure handling</h2>
|
||||
<h2>Persistent actor snapshots</h2>
|
||||
<p>
|
||||
<a href="#code/src/main/java/sample/persistence/ProcessorFailureExample.java" class="shortcut">ProcessorFailureExample.java</a>
|
||||
shows how a processor can delete persistent messages from the journal if they threw an exception. Throwing an exception
|
||||
restarts the processor and replays messages. In order to prevent that the message that caused the exception is replayed,
|
||||
it is marked as deleted in the journal (during invocation of <code>preRestart</code>). This is a common pattern in
|
||||
command-sourcing to compensate write-ahead logging of messages.
|
||||
<a href="#code/src/main/java/sample/persistence/SnapshotExample.java" class="shortcut">SnapshotExample.java</a>
|
||||
demonstrates how persistent actors can take snapshots of application state and recover from previously stored snapshots.
|
||||
Snapshots are offered to persistent actors at the beginning of recovery, before any messages (younger than the snapshot)
|
||||
are replayed.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and run the application main class
|
||||
<b><code>sample.persistence.ProcessorFailureExample</code></b> several times.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
<a href="http://doc.akka.io/docs/akka/2.4-SNAPSHOT/java/lambda-persistence.html#event-sourcing" target="_blank">Event sourcing</a>
|
||||
on the other hand, does not persist commands directly but rather events that have been derived from received commands
|
||||
(not shown here). These events are known to be successfully applicable to current processor state i.e. there's
|
||||
no need for deleting them from the journal. Event sourced processors usually have a lower throughput than command
|
||||
sourced processors, as the maximum size of a write batch is limited by the number of persisted events per received
|
||||
command.
|
||||
<b><code>sample.persistence.SnapshotExample</code></b> several times. With every run, the state offered by the
|
||||
most recent snapshot is printed to <code>stdout</code>, followed by the updated state after sending new persistent
|
||||
messages to the persistent actor.
|
||||
</p>
|
||||
</div>
|
||||
|
||||
<div>
|
||||
<h2>Processor views</h2>
|
||||
<h2>Persistent actor recovery</h2>
|
||||
<p>
|
||||
<a href="#code/src/main/java/sample/persistence/PersistentActorFailureExample.java" class="shortcut">PersistentActorFailureExample.java</a>
|
||||
shows how a persistent actor can throw an exception, restart and restore the state by replaying the events.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and run the application main class
|
||||
<b><code>sample.persistence.PersistentActorFailureExample</code></b> several times.
|
||||
</p>
|
||||
</div>
|
||||
|
||||
<div>
|
||||
<h2>Persistent actor views</h2>
|
||||
<p>
|
||||
<a href="#code/src/main/java/sample/persistence/ViewExample.java" class="shortcut">ViewExample.java</a> demonstrates
|
||||
how a view (<code>ExampleView</code>) is updated with the persistent message stream of a processor
|
||||
(<code>ExampleProcessor</code>). Messages sent to the processor are read from <code>stdin</code>. Views also support
|
||||
snapshotting and can be used in combination with channels in the same way as processors.
|
||||
how a view (<code>ExampleView</code>) is updated with the persistent message stream of a persistent actor
|
||||
(<code>ExamplePersistentActor</code>). Messages sent to the persistent actor are scheduled periodically. Views also support
|
||||
snapshotting to reduce recovery time.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and run the application main class
|
||||
<b><code>sample.persistence.ViewExample</code></b>.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
Views can also receive events that have been persisted by event sourced processors (not shown).
|
||||
</p>
|
||||
</div>
|
||||
|
||||
<div>
|
||||
<h2>Processor conversation recovery</h2>
|
||||
<p>
|
||||
<a href="#code/src/main/java/sample/persistence/ConversationRecoveryExample.java" class="shortcut">ConversationRecoveryExample.java</a>
|
||||
defines two processors that send messages to each other via channels. The reliable delivery properties of channels,
|
||||
in combination with processors, allow these processors to automatically resume their conversation after a JVM crash.
|
||||
</p>
|
||||
<p>
|
||||
To run this example, go to the <a href="#run" class="shortcut">Run</a> tab, and run the application main class
|
||||
<b><code>sample.persistence.ConversationRecoveryExample</code></b> several times.
|
||||
</p>
|
||||
</div>
|
||||
|
||||
</body>
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue