The most common way to use Dubbo is to run it in Spring framework. The following content will guide you to develop a Dubbo application with Spring framework’s XML configuration.
If you don’t want to rely on Spring, you can try using API configuration.
First let’s create a root directory called dubbo-demo:
mkdir dubbo-demo
cd dubbo-demo
Next, we are going to create 3 sub-directories under root directory:
DemoService.java 1：
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
DemoServiceImpl.java 2：
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;
}
}
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>
The demo uses multicast as the registry since it is simple and does not require to extra installation. If you prefer a registry like zookeeper, please check out examples here.
Dubbo use log4j as logging system by default, it also support slf4j, Apache Commons Logging, and JUL logging.
Following is a sample configuration:
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
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
Complete installation steps, see：Consumer demo installation
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>
Consumer.java 3：
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);
}
}
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
Run the org.apache.dubbo.demo.provider.Provider class to start the provider.
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
You can find the complete example code in the Github repository.