[英]Akka distributed pub sub: Java implementation not working
订阅者的主类:Application.java
package com.mynamespace;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import akka.actor.ActorRef;
import akka.actor.ActorSystem;
import akka.actor.Props;
import akka.contrib.pattern.DistributedPubSubExtension;
import akka.contrib.pattern.DistributedPubSubMediator;
import com.mynamespace.actors.SubscriberActor;
@SpringBootApplication
@ComponentScan(basePackages = "com.mynamespace.*")
public class Application {
public static void main(String[] args) throws InterruptedException {
ApplicationContext ctx = SpringApplication.run(Application.class, args);
// get hold of the actor system
ActorSystem system = ctx.getBean(ActorSystem.class);
ActorRef mediator = DistributedPubSubExtension.get(system).mediator();
ActorRef subscriber = system.actorOf(
Props.create(SubscriberActor.class), "subscriber");
// subscribe to the topic named "content"
mediator.tell(new DistributedPubSubMediator.Put(subscriber), subscriber);
// subscriber.tell("init", null);
System.out.println("Running.");
Thread.sleep(5000l);
}
}
订阅者actor:SubscriberActor.java
package com.mynamespace.actors;
import java.util.ArrayList;
import java.util.List;
import akka.actor.UntypedActor;
import com.mynamespace.message.CategoryServiceRequest;
import com.mynamespace.message.CategoryServiceResponse;
public class SubscriberActor extends UntypedActor {
@Override
public void onReceive(Object msg) throws Exception {
if (msg instanceof CategoryServiceRequest) {
System.out.println("Request received for GetCategories.");
CategoryServiceResponse response = new CategoryServiceResponse();
List<String> categories = new ArrayList<>();
categories.add("Food");
categories.add("Fruits");
response.setCatgories(categories);
getSender().tell(response, getSelf());
} else if (msg instanceof String && msg.equals("init")) {
System.out.println("init called");
} else {
System.out
.println("Unhandelled message received for getCategories.");
}
}
}
订阅者的Application.conf
akka {
loglevel = INFO
stdout-loglevel = INFO
loggers = ["akka.event.slf4j.Slf4jLogger"]
extensions = ["akka.contrib.pattern.DistributedPubSubExtension"]
actor {
provider = "akka.cluster.ClusterActorRefProvider"
}
remote {
enabled-transports = ["akka.remote.netty.tcp"]
netty.tcp {
hostname = "127.0.0.1"
port = 0
}
}
cluster {
seed-nodes = [
"akka.tcp://mynamespace-actor-system@127.0.0.1:2551",
"akka.tcp://mynamespace-actor-system@127.0.0.1:2552"]
auto-down-unreachable-after = 10s
}
}
发布者的主要类:Application.java
package com.mynamespace;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import akka.actor.ActorRef;
import akka.actor.ActorSystem;
import akka.actor.Props;
import akka.contrib.pattern.DistributedPubSubExtension;
import akka.contrib.pattern.DistributedPubSubMediator;
import com.mynamespace.actors.PublisherActor;
@SpringBootApplication
@ComponentScan(basePackages = "com.mynamespace.*")
public class Application {
public static void main(String[] args) throws InterruptedException {
ApplicationContext ctx = SpringApplication.run(Application.class, args);
// get hold of the actor system
ActorSystem system = ctx.getBean(ActorSystem.class);
ActorRef mediator = DistributedPubSubExtension.get(system).mediator();
ActorRef publisher = system.actorOf(Props.create(PublisherActor.class),
"publisher");
mediator.tell(new DistributedPubSubMediator.Put(publisher), publisher);
Thread.sleep(5000);
publisher.tell("hi", publisher);
System.out.println("Running.");
}
}
PublisherActor.java
package com.mynamespace.actors;
import scala.concurrent.Future;
import akka.actor.ActorRef;
import akka.actor.UntypedActor;
import akka.contrib.pattern.DistributedPubSubExtension;
import akka.contrib.pattern.DistributedPubSubMediator;
import akka.dispatch.Mapper;
import akka.pattern.Patterns;
import akka.util.Timeout;
import com.mynamespace.message.CategoryServiceRequest;
import com.mynamespace.message.CategoryServiceResponse;
public class PublisherActor extends UntypedActor {
// activate the extension
ActorRef mediator = DistributedPubSubExtension.get(getContext().system())
.mediator();
public void onReceive(Object msg) {
if (msg instanceof String) {
Timeout timeOut = new Timeout(50000l);
mediator.tell(new DistributedPubSubMediator.Send(
"/user/subscriber", new CategoryServiceRequest()),
getSelf());
Future<Object> response = Patterns.ask(mediator,
new DistributedPubSubMediator.Send("/user/subscriber",
new CategoryServiceRequest()), timeOut);
Future<CategoryServiceResponse> finalresponse = response.map(
new Mapper<Object, CategoryServiceResponse>() {
@Override
public CategoryServiceResponse apply(Object parameter) {
CategoryServiceResponse responseFromRemote = (CategoryServiceResponse) parameter;
System.out.println("received:: list of size:: "
+ responseFromRemote.getCatgories().size());
return responseFromRemote;
}
}, getContext().system().dispatcher());
} else if (msg instanceof DistributedPubSubMediator.SubscribeAck) {
System.out.println("subscribbed.......");
} else {
unhandled(msg);
}
}
}
发布者的应用程序配置与订阅者相同。 两者都在同一系统上的不同端口上运行。
我在本地系统上定义并运行了两个种子节点。 不知何故,我无法通过DistributedPubSub Mediator从生产者(两者都在不同的节点上运行)ASK / TELL订阅者。
运行Subscriber然后发布者:我没有在stdout / logs中打印任何异常或任何死信引用。
是否有可能查看哪个actor引用了我的调解员?
需要帮助来查找问题或可能的问题。
我遇到了同样的问题,在@spam的评论和我自己的实验后,我可以推荐的是使用发布/订阅组和sendOneMessageToEachGroup=true
。
它是否应该只在本地发送? 如果是这样,文档没有明确说明。 但我也可以通过代码告诉我,文档的这个特定部分显然已经被忽略了(因为更改了类名,但是不调用它们,在之前的例子中调用前面的那些)
希望这可以帮助任何有这个问题的人,因为文档显然有点误导
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