Dubbo

 

Overview

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Serving 1,000+ services with 1,000,000,000+ invocations everyday, Dubbo becomes the key part of Alibaba's SOA solution and has been deployed to the whole alibaba.com family:

So, What is Dubbo?

Dubbo [] is a distributed service framework enpowers applications with service import/export capability with high performance RPC.

It's composed of three kernel parts:

• Remoting: a network communication framework provides sync-over-async and request-response messaging.
• Clustering: a remote procedure call abstraction with load-balancing/failover/clustering capabilities.
• Registry: a service directory framework for service registration and service event publish/subscription

Dubbo can:

• Integrate different types of RPC solutions(RMI/Hessian...) with unified behavior by the abstraction layer of RPC
• Support out-of-box, plug-able load balancing and fault tolerance strategies.
• Achieve graceful service upgrade/downgrade with service registry.

Quick Start

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Dubbo also support usage WITHOUT spring, please refer to: API Reference

Service Provider

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See: Demo Provider Installation

Define the service interface:

DemoService.java

package com.alibaba.dubbo.demo;   public interface DemoService {        String sayHello(String name);   }

Provide the service implementation

DemoServiceImpl.java

package com.alibaba.dubbo.demo.provider;   import com.alibaba.dubbo.demo.DemoService;   public class DemoServiceImpl implements DemoService {        public String sayHello(String name) {          return "Hello " + name;      }   }

Setup the spring configuration

provider.xml

<? xml version = "1.0" encoding = "UTF-8" ?> < beans xmlns = "http://www.springframework.org/schema/beans"      xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"      xmlns:dubbo = "http://code.alibabatech.com/schema/dubbo"      xsi:schemaLocation="http://www.springframework.org/schema/beans          http://www.springframework.org/schema/beans/spring-beans.xsd          http://code.alibabatech.com/schema/dubbo          http://code.alibabatech.com/schema/dubbo/dubbo.xsd          ">        <!-- Application name -->      < dubbo:application name = "hello-world-app"  />        <!-- registry address, used for service to register itself -->      < dubbo:registry address = "multicast://224.5.6.7:1234" />        <!-- expose this service through dubbo protocol, through port 20880 -->      < dubbo:protocol name = "dubbo" port = "20880" />        <!-- which service interface do we expose? -->      < dubbo:service interface = "com.alibaba.dubbo.demo.DemoService" ref = "demoService" />        <!-- designate implementation -->      < bean id = "demoService" class = "com.alibaba.dubbo.demo.provider.DemoServiceImpl" />   </ beans >

Kick it off with following java code

Provider.java

import org.springframework.context.support.ClassPathXmlApplicationContext;   public class Provider {        public static void main(String[] args) throws Exception {          ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext( new String[] { "provider.xml" });          context.start();            System.out.println( "Press any key to exit." );          System.in.read();      }   }

Congrats! The DemoService now is exported by dubbo and waiting for incoming requests at port 20880.

Service Consumer

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See: Demo Consumer Installation

Setup the spring XML

consumer.xml

<? xml version = "1.0" encoding = "UTF-8" ?> < beans xmlns = "http://www.springframework.org/schema/beans"      xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"      xmlns:dubbo = "http://code.alibabatech.com/schema/dubbo"      xsi:schemaLocation="http://www.springframework.org/schema/beans          http://www.springframework.org/schema/beans/spring-beans.xsd          http://code.alibabatech.com/schema/dubbo          http://code.alibabatech.com/schema/dubbo/dubbo.xsd          ">        <!-- consumer application name -->      < dubbo:application name = "consumer-of-helloworld-app"  />        <!-- registry address, used for consumer to discover services -->      < dubbo:registry address = "multicast://224.5.6.7:1234" />        <!-- which service to consume? -->      < dubbo:reference id = "demoService" interface = "com.alibaba.dubbo.demo.DemoService" />   </ beans >

Client side java code.

Consumer.java

import org.springframework.context.support.ClassPathXmlApplicationContext; import com.alibaba.dubbo.demo.DemoService;   public class Consumer {        public static void main(String[] args) throws Exception {          ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext( new String[] { "consumer.xml" });          context.start();            DemoService demoService = (DemoService)context.getBean( "demoService" ); // get service invocation proxy          String hello = demoService.sayHello( "world" ); // do invoke!            System.out.println( hello ); // cool, how are you~      }   }

For more, please click here for a complete user guide.