dubbo user guider notes of the two Quick start

Quick start

This section is relatively simple, but we, as a beginner, we'd better get knock. Deepen our understanding of the whole process and structure.

The most common way is to run it in the spring Dubbo framework. The following contents will guide you use spring xml configuration to develop a Dubbo application. Of course also be configured to use the API.

Service provider

Defining service interfaces

DemoService.java ：

package org.apache.dubbo.demo;

public interface DemoService {
    String sayHello(String name);

}

The project structure should look like this:

.
├── dubbo-demo-api
│   ├── pom.xml
│   └── src
│       └── main
│           └── java
│               └── org
│                   └── apache
│                       └── dubbo
│                           └── demo
│                               └── DemoService.java

Implement interface in service provider

DemoServiceImpl.java ：

package org.apache.dubbo.demo.provider;
import org.apache.dubbo.demo.DemoService;

public class DemoServiceImpl implements DemoService {
    public String sayHello(String name) {
        return "Hello " + name;
    }
}

Exposing service with Spring configuration

provider.xml：

<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">

    <!-- provider's application name, used for tracing dependency relationship -->
    <dubbo:application name="demo-provider"/>
    <!-- use multicast registry center to export service -->
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <!-- use dubbo protocol to export service on port 20880 -->
    <dubbo:protocol name="dubbo" port="20880"/>
    <!-- service implementation, as same as regular local bean -->
    <bean id="demoService" class="org.apache.dubbo.demo.provider.DemoServiceImpl"/>
    <!-- declare the service interface to be exported -->
    <dubbo:service interface="org.apache.dubbo.demo.DemoService" ref="demoService"/>
</beans>

This demo uses a simple multicast as a registration center

Configure the logging system

Dubbo default log4j as a logging system, it also supports slf4j, Apache Commons Logging, and JUL logging.
Simple configuration is as follows:
log4j.properties

###set log levels###
log4j.rootLogger=info, stdout
###output to the console###
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%d{dd/MM/yy hh:mm:ss:sss z}] %t %5p %c{2}: %m%n

Bootstrap the service provider

Provider.java

package org.apache.dubbo.demo.provider;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Provider {

    public static void main(String[] args) throws Exception {
        System.setProperty("java.net.preferIPv4Stack", "true");
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-provider.xml"});
        context.start();
        System.out.println("Provider started.");
        System.in.read(); // press any key to exit
    }
}

Finally, the project structure should look like this:

├── dubbo-demo-provider
│   ├── pom.xml
│   └── src
│       └── main
│           ├── java
│           │   └── org
│           │       └── apache
│           │           └── dubbo
│           │               └── demo
│           │                   └── provider
│           │                       ├── DemoServiceImpl.java
│           │                       └── Provider.java
│           └── resources
│               ├── META-INF
│               │   └── spring
│               │       └── dubbo-demo-provider.xml
│               └── log4j.properties

Service consumer

Using the Spring configuration to reference a remote service

consumer.xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
       http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd">

    <!-- consumer's application name, used for tracing dependency relationship (not a matching criterion),
    don't set it same as provider -->
    <dubbo:application name="demo-consumer"/>
    <!-- use multicast registry center to discover service -->
    <dubbo:registry address="multicast://224.5.6.7:1234"/>
    <!-- generate proxy for the remote service, then demoService can be used in the same way as the
    local regular interface -->
    <dubbo:reference id="demoService" check="false" interface="org.apache.dubbo.demo.DemoService"/>
</beans>

Bootstrap the consumer

Consumer.java ：

import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.apache.dubbo.demo.DemoService;
 
public class Consumer {
    public static void main(String[] args) throws Exception {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[] {"META-INF/spring/dubbo-demo-consumer.xml"});
        context.start();
        // Obtaining a remote service proxy
        DemoService demoService = (DemoService)context.getBean("demoService");
        // Executing remote methods
        String hello = demoService.sayHello("world");
        // Display the call result
        System.out.println(hello);
    }
}

Config the logging system

This is the same as how to config it on provider side.

Finally, the project structure should be look like this:

├── dubbo-demo-consumer
│   ├── pom.xml
│   └── src
│       └── main
│           ├── java
│           │   └── org
│           │       └── apache
│           │           └── dubbo
│           │               └── demo
│           │                   └── consumer
│           │                       └── Consumer.java
│           └── resources
│               ├── META-INF
│               │   └── spring
│               │       └── dubbo-demo-consumer.xml
│               └── log4j.properties

Start the demo

Start service provider

Run the org.apache.dubbo.demo.provider.Provider class to start the provider.

Start service consumer

Run the org.apache.dubbo.demo.provider.Consumer class to start the consumer, and you should be able to see the following result:

Hello world