Apache Dubbo, a Java-Based RPC Framework, Graduates to Top ...

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The Apache Software Foundation recently announced Apache Dubbo as a top-level project. Apache Dubbo is an open source, remote procedure call framework based on Java. It was originally developed at Alibaba, open-sourced in 2011, and entered the Apache Incubator in February 2018. Dubbo brings key functionalities such as interface-based remote call, fault tolerance and load balancing, and automatic service registration and discovery.

The Dubbo architecture is shown below:

(Image taken from https://dubbo.apache.org/ )


     Container

is responsible for launching, loading, and running the service


     Provider


     Provider

registers its services to


     Register

during its initialization


     Consumer

subscribes the services it needs from the


     Register

when it starts


     Register

returns the


     Provider

s list to


     Consumer

, and when a change occurs, the


     Register

push the changed data to


     Consumer

Based on a soft load balancing algorithm, the


     Consumer

will select one of the


     Provider

s and executes the invocation, automatically choose another


     Provider

when a fail occurs.

Both


     Consumer

and


     Provider

will count the number service invocations and time-consuming in memory, and send the statistics to


     Monitor

every minute.

Apache Dubbo features include:

A transparent interface based RPC

Intelligent load balancing, which supports multiple load balancing strategies out of the box

Automatic service registration and discovery

High extensibility, micro-kernel and plugin design which ensures that it can easily be extended by third party implementation across core features like protocol, transport, and serialization

Runtime traffic routing, which can be configured at runtime so that traffic can be routed according to different rules, making it easy to support features such as blue-green deployment, data center aware routing, etc

Visualized service governance, which provides rich tools for service governance and maintenance such as querying service metadata, health status, and statistics

To get started using Dubbo, developers first add the Maven dependency:


    <dependencies>
    <dependency>
        <groupId>org.apache.dubbo</groupId>
        <artifactId>dubbo</artifactId>
        <version>2.7.2<</version>
    </dependency>
    <dependency>
        <groupId>org.apache.dubbo</groupId>
        <artifactId>dubbo-dependencies-zookeeper</artifactId>
        <version>2.7.2<</version>
        <type>pom</type>
    </dependency>
</dependencies>
    
     Next, a service interface is defined and implemented in the provider:
    
    
     package org.apache.dubbo.samples.api;
//service interface
public interface GreetingService {
    String sayHello(String name);
//provider, implementation of service interface
public class GreetingServiceImpl implements GreetingService {
    @Override
    public String sayHello(String name) {
        return "Hello " + name;
     
      The provider would be configured as follows:
     
     
      package org.apache.dubbo.demo.provider;
import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.apache.dubbo.config.ServiceConfig;
import org.apache.dubbo.samples.api.GreetingService;
import java.io.IOException;
public class Application {
    public static void main(String[] args) throws IOException {
        ServiceConfig
      
       serviceConfig = new ServiceConfig
       
        ();
        serviceConfig.setApplication(new ApplicationConfig("first-dubbo-provider"));
        serviceConfig.setRegistry(new RegistryConfig("multicast://224.5.6.7:1234"));
        serviceConfig.setInterface(GreetingService.class);
        serviceConfig.setRef(new GreetingServiceImpl());
        serviceConfig.export();
        System.in.read();
        
         And then built and run:
        
        
         # mvn clean package
# mvn -Djava.net.preferIPv4Stack=true -Dexec.mainClass=org.apache.dubbo.demo.provider.Application exec:java
         
          The following code snippets show how to create a consumer:
         
         
          package org.apache.dubbo.demo.consumer;
import org.apache.dubbo.config.ApplicationConfig;
import org.apache.dubbo.config.ReferenceConfig;
import org.apache.dubbo.config.RegistryConfig;
import org.apache.dubbo.samples.api.GreetingService;
public class Application {
    public static void main(String[] args) {
        ReferenceConfig
          
           referenceConfig = new ReferenceConfig
           
            ();
        referenceConfig.setApplication(new ApplicationConfig("first-dubbo-consumer"));
        referenceConfig.setRegistry(new RegistryConfig("multicast://224.5.6.7:1234"));
        referenceConfig.setInterface(GreetingService.class);
        GreetingService greetingService = referenceConfig.get();
        System.out.println(greetingService.sayHello("world"));
            
             Beginning a new project using Apache Dubbo is relatively simple; developers can follow the steps above, or by use Dubbo's Spring
             
              initializr
             
             , which is basically a fork of Spring initializr. In addition to Java, Dubbo supports
             
              Node.js
             
             ,
             
              Python
             
             , and
             
              PHP
             
             .
            
            
             Apache Dubbo is in use at companies such as Alibaba Group, China Life, China Telecom, Dangdang, Didi Chuxing, Haier, Industrial and Commercial Bank of China, NetEase, Qunar, and Youzan.
            
            
             More details about Dubbo can be found at
             
              https://dubbo.apache.org
             
             . Developers who want to contribute should access the
             
              contributor guide
             
             . There is also extensive
             
              documentation
             
             available.
            
            
             
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