dubbo user guider笔记之三配置方式详解

配置方式详解

目前dubbo提供了四种配置方式，他们分别是：

1. XML Configuration
2. Properties Configurtion
3. API Configuration
4. Annotation Configuration

下面我们来分别详细的介绍一下他们

XML Configuration

之前写过一个关于xml配置的入门demo，不妨先看看。

provider.xml demo

<?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://dubbo.apache.org/schema/dubbo"
    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">  
    
    <dubbo:application name="hello-world-app"  />  
    <dubbo:registry address="multicast://224.5.6.7:1234" />  
    <dubbo:protocol name="dubbo" port="20880" />  
    <dubbo:service interface="org.apache.dubbo.demo.DemoService" ref="demoServiceLocal" />  
    <dubbo:reference id="demoServiceRemote" interface="org.apache.dubbo.demo.DemoService" />  
</beans>

所有的标签都支持自定义的参数，所以我们可以满足不同扩展点的特殊配置需求，
例如：

<dubbo:protocol name="jms">
    <dubbo:parameter key="queue" value="your_queue" />
</dubbo:protocol>

or

 <dubbo:protocol name="jms" p:queue="your_queue" />  

关于这些标签的具体含义，暂时先不讲，现有一个大概映像即可。

The relations between configuration tags

标签名	目的（作用）	介绍
dubbo:service/	Service Export	Used to export service, define service metadata, export service with multiple protocols, register service to multiple registries
dubbo:reference/	Service Reference	Used to create a remote proxy, subscribe to multiple registries
dubbo:protocol/	Protocol Config	Configure the protocol for services on provider side, the consumer side follows.
dubbo:application/	Application Config	Applies to both provider and consumer.
dubbo:module/	Module Config	Optional.
dubbo:registry/	Registry Center	Registry info: address, protocol, etc.
dubbo:monitor/	Monitor Center	Monitor info: address, address, etc. Optional.
dubbo:provider/	Default Config for Providers	Default Config for ServiceConfigs. Optional.
dubbo:consumer/	Default Config for Consumers	Default Config for ReferenceConfigs. Optional.
dubbo:method/	Method level Config	Method level Config for ServiceConfig and ReferenceConfig.
dubbo:argument/	Argument Config	Used to specify the method parameter configuration.

Overrides and Priorities(属性的覆盖和优先级)

拿timeout做一个例子 (retries, loadbalance, actives 也适用)，从高到低的优先级如下所示：

• 方法级，接口级，默认/全局级
• 相同等级的情况下，consumer的优先级比provider的更高

provider端的配置会通过registry 传递给consumer 端。

provider 最好为每个服务都设置一个超时时间，因为provider能够准确的知道每个方法应该去执行多长时间。假如consumer 同时引入了多个服务，它并不需要关心每个服务超时时间的设置。

理论上，ReferenceConfig 所支持的所有的配置项都可以由 ConsumerConfig, ServiceConfig, ProviderConfig来配置（缺省使用的意思，如果没配，就用他们的）。

1. 需要spring 3.2.16+,
   详见公告：“xmlns:p="http://www.springframework.org/schema/p”
2. 引用bean默认是懒加载的，除非它被另外一个实例引用了。假如你需要提前初始化，这样配置【<dubbo:reference ... init="true" />】

Properties Configuration（属性文件配置）

对于不需要多注册中心，多协议的比较简单的应用，并且需要在spring container里共享配置的，我们可以使用dubbo.properties作为默认配置。

Dubbo将自动加载classpath根目录下的dubbo.properties文件，当让也可以使用JVM的参数-Ddubbo.properties.file=xxx.properties来指定地址。

Mapping Rules

属性文件配置跟xml的配置形式有一个简单的映射规则：即将xml的tag名和属性名组合起来，用【.】分隔即可。每个属性占一行。

• dubbo.application.name=foo 相当于 <dubbo:application name="foo" />
• dubbo.registry.address=10.20.153.10:9090 相当于 <dubbo:registry address="10.20.153.10:9090" />

如果xml配置中有多余一个的tags，我们可以使用id来区分开。如果你不指定一个id，ti将被应用到所有的tags。

• dubbo.protocol.rmi.port=1099 等同于 <dubbo:protocol id="rmi" name="rmi" port="1099" />
• dubbo.registry.china.address=10.20.153.10:9090 等同于 <dubbo:registry id="china" address="10.20.153.10:9090" />

一个典型的dubbo.properties配置如下：

dubbo.application.name=foo
dubbo.application.owner=bar
dubbo.registry.address=10.20.153.10:9090

Overrides and Priorities

优先级由高到低依次是：

• JVM -D参数，当你部署或者启动应用时，使用它可以很容易的覆盖掉配置，又比如改变buddo协议的端口
• XML, XML中的配置会覆盖dubbo.properties中的
• Properties，一般作为默认值，仅仅当以上俩者都没配置时它才生效

API Configuration

所有的API属性在XML中都有与之对应的配置，比如，ApplicationConfig.setName("xxx") 等同于 <dubbo:application name="xxx" />

Provider Side

import org.apache.dubbo.rpc.config.ApplicationConfig;
import org.apache.dubbo.rpc.config.RegistryConfig;
import org.apache.dubbo.rpc.config.ProviderConfig;
import org.apache.dubbo.rpc.config.ServiceConfig;
import com.xxx.XxxService;
import com.xxx.XxxServiceImpl;
 
// Implementation
XxxService xxxService = new XxxServiceImpl();
 
// Application Info
ApplicationConfig application = new ApplicationConfig();
application.setName("xxx");
 
// Registry Info
RegistryConfig registry = new RegistryConfig();
registry.setAddress("10.20.130.230:9090");
registry.setUsername("aaa");
registry.setPassword("bbb");
 
// Protocol
ProtocolConfig protocol = new ProtocolConfig();
protocol.setName("dubbo");
protocol.setPort(12345);
protocol.setThreads(200);
 
// NOTES: ServiceConfig holds the serversocket instance and keeps connections to registry, please cache it for performance.
 
// Exporting
ServiceConfig<XxxService> service = new ServiceConfig<XxxService>(); // In case of memory leak, please cache.
service.setApplication(application);
service.setRegistry(registry); // Use setRegistries() for multi-registry case
service.setProtocol(protocol); // Use setProtocols() for multi-protocol case
service.setInterface(XxxService.class);
service.setRef(xxxService);
service.setVersion("1.0.0");
 
// Local export and register
service.export();

Consumer Side

import org.apache.dubbo.rpc.config.ApplicationConfig;
import org.apache.dubbo.rpc.config.RegistryConfig;
import org.apache.dubbo.rpc.config.ConsumerConfig;
import org.apache.dubbo.rpc.config.ReferenceConfig;
import com.xxx.XxxService;
 
// Application Info
ApplicationConfig application = new ApplicationConfig();
application.setName("yyy");
 
// Registry Info
RegistryConfig registry = new RegistryConfig();
registry.setAddress("10.20.130.230:9090");
registry.setUsername("aaa");
registry.setPassword("bbb");
 
// NOTES: ReferenceConfig holds the connections to registry and providers, please cache it for performance.
 
// Refer remote service
ReferenceConfig<XxxService> reference = new ReferenceConfig<XxxService>(); // In case of memory leak, please cache.
reference.setApplication(application);
reference.setRegistry(registry); 
reference.setInterface(XxxService.class);
reference.setVersion("1.0.0");
 
// Use xxxService just like a local bean
XxxService xxxService = reference.get(); // NOTES: Please cache this proxy instance.

Annotation Configuration

Provider Side

Service annotation for exporting

@Service
public class AnnotationServiceImpl implements AnnotationService {
    @Override
    public String sayHello(String name) {
        return "annotation: hello, " + name;
    }
}

Add application sharing configuration

# dubbo-provider.properties
dubbo.application.name=annotation-provider
dubbo.registry.address=zookeeper://127.0.0.1:2181
dubbo.protocol.name=dubbo
dubbo.protocol.port=20880

Spring scan path

@Configuration
@EnableDubbo(scanBasePackages = "org.apache.dubbo.samples.simple.annotation.impl")
@PropertySource("classpath:/spring/dubbo-provider.properties")
static public class ProviderConfiguration {
       
}

Consumer Side

Reference annotation for reference

@Component("annotationAction")
public class AnnotationAction {

    @Reference
    private AnnotationService annotationService;
    
    public String doSayHello(String name) {
        return annotationService.sayHello(name);
    }
}

Add application sharing configuration

# dubbo-consumer.properties
dubbo.application.name=annotation-consumer
dubbo.registry.address=zookeeper://127.0.0.1:2181
dubbo.consumer.timeout=3000

Spring scan path

@Configuration
@EnableDubbo(scanBasePackages = "org.apache.dubbo.samples.simple.annotation.action")
@PropertySource("classpath:/spring/dubbo-consumer.properties")
@ComponentScan(value = {"org.apache.dubbo.samples.simple.annotation.action"})
static public class ConsumerConfiguration {

}