Akka 实践之(三) 远程部署

比眉伴天荒 2022-07-15 01:22 249阅读 0赞

Akka 可以支持客户端和服务端远程部署，这点对与高并发分布式调用非常有利。 在上篇的代码基础上，新增2个类，LookupActor和LookupApplication.java

# 1、首先看一下类图 #

![Image 1][]

# 2、 源码 #

在本例中，将远程创建CalculatorActor 对象，然后通过指定path的方式创建这个对象的远程Actor（其实我认为是这个对象的代理）

final String path = "akka.tcp://CalculatorSystem@127.0.0.1:8552/user/calculator";
 final ActorRef actor = system.actorOf( Props.create(LookupActor.class, path), "lookupActor");

LookupActor和 LookupApplication的源码如下，重点关注是如何创建远程对象，以及如何获取对远程对象的使用。

package com.cwqsolo.study.akka.demo;
 
 import static java.util.concurrent.TimeUnit.SECONDS;
 import scala.concurrent.duration.Duration;
 import akka.actor.ActorRef;
 import akka.actor.ActorIdentity;
 import akka.actor.Identify;
 import akka.actor.Terminated;
 import akka.actor.UntypedActor;
 import akka.actor.ReceiveTimeout;
 import akka.japi.Procedure;
 
 public class LookupActor extends UntypedActor {
 
 private final String path;
 private ActorRef calculator = null;
 
 public LookupActor(String path) {
 this.path = path;
 sendIdentifyRequest();
 }
 
 private void sendIdentifyRequest() {
 getContext().actorSelection(path).tell(new Identify(path), getSelf());
 getContext()
 .system()
 .scheduler()
 .scheduleOnce(Duration.create(3, SECONDS), getSelf(),
 ReceiveTimeout.getInstance(), getContext().dispatcher(), getSelf());
 }
 
 @Override
 public void onReceive(Object message) throws Exception {
 if (message instanceof ActorIdentity) {
 calculator = ((ActorIdentity) message).getRef();
 if (calculator == null) {
 System.out.println("Remote actor not available: " + path);
 } else {
 getContext().watch(calculator);
 getContext().become(active, true);
 }
 
 } else if (message instanceof ReceiveTimeout) {
 sendIdentifyRequest();
 
 } else {
 System.out.println("Not ready yet");
 
 }
 }
 
 Procedure<Object> active = new Procedure<Object>() {
 @Override
 public void apply(Object message) {
 if (message instanceof Op.MathOp) {
 // send message to server actor
 calculator.tell(message, getSelf());
 
 } else if (message instanceof Op.AddResult) {
 Op.AddResult result = (Op.AddResult) message;
 System.out.printf("Add result: %d + %d = %d\n", result.getN1(),
 result.getN2(), result.getResult());
 
 } else if (message instanceof Op.SubtractResult) {
 Op.SubtractResult result = (Op.SubtractResult) message;
 System.out.printf("Sub result: %d - %d = %d\n", result.getN1(),
 result.getN2(), result.getResult());
 
 } else if (message instanceof Terminated) {
 System.out.println("Calculator terminated");
 sendIdentifyRequest();
 getContext().unbecome();
 
 
 
 } else if (message instanceof ReceiveTimeout) {
 // ignore
 
 } else {
 unhandled(message);
 }
 
 }
 };
 }

可以看到LookupActor 与上节中的CreationActor类没有什么区别，重点是LookupApplication类源码。

package com.cwqsolo.study.akka.demo;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
 import java.util.Random;
 
 //import scala.concurrent.duration.Duration;
 //import akka.actor.ActorRef;
 //import akka.actor.ActorSystem;
 //import akka.actor.Props;
 import com.typesafe.config.ConfigFactory;
 
 import java.util.Arrays; 
 import java.util.concurrent.Callable; 
 import scala.concurrent.*;
 import scala.concurrent.duration.Duration;
 import akka.actor.ActorRef; 
 import akka.actor.ActorSystem; 
 import akka.actor.Props; 
 
 public class LookupApplication {
 public static void main(String[] args) {
 if (args.length == 0 || args[0].equals("Calculator"))
 startRemoteCalculatorSystem();
 if (args.length == 0 || args[0].equals("Lookup"))
 startRemoteLookupSystem();
 
 }
 
 public static void startRemoteCalculatorSystem() {
 final ActorSystem system = ActorSystem.create("CalculatorSystem",
 ConfigFactory.load(("calculator")));
 final ActorRef calActor = system.actorOf(Props.create(CalculatorActor.class), "calculator");
 //calActor.
 System.out.println("Started CalculatorSystem");
 }
 
 public static void startRemoteLookupSystem() {
 
 final ActorSystem system = ActorSystem.create("LookupSystem",
 ConfigFactory.load("remotelookup"));
 final String path = "akka.tcp://CalculatorSystem@127.0.0.1:8552/user/calculator";
 final ActorRef actor = system.actorOf(
 Props.create(LookupActor.class, path), "lookupActor");
 
 System.out.println("Started LookupSystem");
 final Random r = new Random();
 system.scheduler().schedule(Duration.create(1, SECONDS),
 Duration.create(1, SECONDS), new Runnable() {
 @Override
 public void run() {
 if (r.nextInt(100) % 2 == 0) {
 actor.tell(new Op.Add(r.nextInt(100), r.nextInt(100)), null);
 } else {
 actor.tell(new Op.Subtract(r.nextInt(100), r.nextInt(100)), null);
 }
 
 }
 }, system.dispatcher());
 
 }
 }

标红代码这里要注意，这里是关键，而且可以看到，这里用到了配置文件（一开始，这里没有搞懂，运行起来都是无法找到远程对象）

配置文件有3个

common.conf

[root@archive akka]# cat common.conf
 akka { 
 actor { 
 provider = "akka.remote.RemoteActorRefProvider" 
 } 
 
 remote { 
 enabled-transports = ["akka.remote.netty.tcp"] 
 netty.tcp { 
 hostname = "127.0.0.1" 
 } 
 } 
 }

[root@archive akka]# cat calculator.conf
 include "common" 
 
 akka { 
 # LISTEN on tcp port 2552 
 remote.netty.tcp.port = 8552 
 }

[root@archive akka]# cat remotelookup.conf 
 include "common"
 
 akka {
 remote.netty.tcp.port = 2553
 }

从上面的配置文件可以看到， calculator对象在8552端口进行监听，  lookup对象通过remotelookup创建了 2553端口的监听，lookup对象通过path 获取

到calculator对象的引用（代理），然后就可以进行对象间的调用。

# 3、执行结果 #

\[root@archive akka\]\# sh  ./start.sh  
java version "1.7.0\_80"  
Java(TM) SE Runtime Environment (build 1.7.0\_80-b15)  
Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)  
\[INFO\] \[10/27/2016 16:48:26.956\] \[main\] \[Remoting\] Starting remoting  
\[INFO\] \[10/27/2016 16:48:27.234\] \[main\] \[Remoting\] Remoting started; listening on addresses :\[akka.tcp://CalculatorSystem@127.0.0.1:8552\]  
\[INFO\] \[10/27/2016 16:48:27.236\] \[main\] \[Remoting\] Remoting now listens on addresses: \[akka.tcp://CalculatorSystem@127.0.0.1:8552\]  
Started CalculatorSystem  
\[INFO\] \[10/27/2016 16:48:27.311\] \[main\] \[Remoting\] Starting remoting  
\[INFO\] \[10/27/2016 16:48:27.339\] \[main\] \[Remoting\] Remoting started; listening on addresses :\[akka.tcp://LookupSystem@127.0.0.1:2553\]  
\[INFO\] \[10/27/2016 16:48:27.339\] \[main\] \[Remoting\] Remoting now listens on addresses: \[akka.tcp://LookupSystem@127.0.0.1:2553\]  
Started LookupSystem  
Calculating 9 - 61  
Sub result: 9 - 61 = -52  
Calculating 51 - 86  
Sub result: 51 - 86 = -35  
Calculating 64 - 30  
Sub result: 64 - 30 = 34  
Calculating 38 + 71  
Add result: 38 + 71 = 109  
Calculating 51 - 73  
Sub result: 51 - 73 = -22  
Calculating 29 + 12  
Add result: 29 + 12 = 41

# 4、注意内容 #

4.1 因为引入了配置文件，需要使用google的配置文件类protobuf-java-2.5.0.jar

4.2 打包运行

我是eclipse环境中调试后，放centos执行的，一开始把代码和依赖库打包在一起，执行会报错。最后是将依赖库单独在centos上建一个lib，只打包代码部分，这样执行才没有问题。

![Center][]

[root@archive akka]# Exception in thread "main" com.typesafe.config.ConfigException$Missing: No configuration setting found for key 'akka.version'
 at com.typesafe.config.impl.SimpleConfig.findKey(SimpleConfig.java:124)
 at com.typesafe.config.impl.SimpleConfig.find(SimpleConfig.java:145)

或者是这样

![Center 1][]

Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)
 [root@archive akka]# Exception in thread "main" java.lang.NoClassDefFoundError: scala/concurrent/ExecutionContext
 at java.lang.Class.getDeclaredMethods0(Native Method)
 at java.lang.Class.privateGetDeclaredMethods(Class.java:2625)
 at java.lang.Class.getMethod0(Class.java:2866)
 at java.lang.Class.getMethod(Class.java:1676)

最后通过只打包自己的代码， lib库单独放置的方式解决

[Image 1]: 
[Center]: /images/20220715/43d55c0e53cb44809461b4c0588ce1bb.png
[Center 1]: /images/20220715/b9801ba50bae4dfcb76a53d96268fe17.png