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    Dubbo Basic Usage - Dubbo Consumer Configuration

    This article will introduce you the basics of consumer configurations.

    Dubbo Consumer Configuration

    Consumer Configuration Detailed

    There are 3 ways to configure the Dubbo Consumer: XML configuration, API call mode configuration, and annotation mode configuration.

    XML Configuration

    Example of the simplest configuration:
    
<?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:reference id="demoServiceRemote" interface="com.alibaba.dubbo.demo.DemoService" />
</beans>

    For the supported configuration tags and corresponding configuration items, refer to the usage in the provider.

    Next, focus on the configuration of <dubbo:reference/>.

    • <dubbo:reference/> List of main attributes supported:
    Property NameDescription
    idservice reference id, as java bean id, requires unique
    Interfaceinterface name for finding services
    versionversion number, consistent with the service provider’s version
    timeoutservice method call timeout (ms)
    retriesThe number of retry attempts by the remote service, excluding the first call, no need to retry, please set to 0
    ConnectionsFor each provider’s maximum number of connections, rmi, http, hessian, etc. The short connection protocol indicates the number of restricted connections, and the dubbo equal-length connection association indicates the number of long connections established
    LoadbalanceLoad balancing policy, optional values: random, roundrobin, leastactive, respectively: random, polling, least active call
    asyncWhether to execute asynchronously, unreliable asynchronous, just ignore return value, do not block execution thread
    genericgeneralized call, can bypass
    checkCheck if the provider exists at startup, true error, false ignore
    ActivesMaximum concurrent calls per method per service consumer

    For other configuration properties, please refer to xsd: http://dubbo.apache.org/schema/dubbo/dubbo.xsd

    • <dubbo:method/> As a child of <dubbo:reference/>, it can be configured for methods. The more commonly used attributes are:
    Property NameDescription
    executesrequest ceiling for service execution
    retriesTimeout retries
    timeoutcall timeout
    LoadbalanceLoad balancing policy, optional values: random, roundrobin, leastactive, respectively: random, polling, least active call
    asyncWhether to execute asynchronously, unreliable asynchronous, just ignore return value, do not block execution thread
    ActivesMaximum concurrent call limit per service consumer

    For other properties, you can refer to xsd above.

    Configured coverage relationship

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    Coverage diagram for configuration

    It contains the configuration of the consumer side and the provider, pay attention to the distinction.

    annotation

    Reference Annotation Remote Service
    
Public class AnnotationConsumeService {

    @com.alibaba.dubbo.config.annotation.Reference
    Public AnnotateService annotateService;

    // ...

}

    The configuration in this way is the same as the previous configuration in xml.

    To specify the way dubbo scans the path, refer to the implementation of the provider in the previous section.

    api direct trigger

    Import com.alibaba.dubbo.rpc.config.ApplicationConfig;
Import com.alibaba.dubbo.rpc.config.RegistryConfig;
Import com.alibaba.dubbo.rpc.config.ConsumerConfig;
Import com.alibaba.dubbo.rpc.config.ReferenceConfig;
Import com.xxx.XxxService;
// current application configuration

ApplicationConfig application = new ApplicationConfig();
application.setName("yyy");
// Connect to the registry configuration
RegistryConfig registry = new RegistryConfig();
registry.setAddress("10.20.130.230:9090");
registry.setUsername("aaa");
registry.setPassword("bbb");
 
// Note: ReferenceConfig is a heavy object that internally encapsulates the connection to the registry and the connection to the service provider.
// reference remote service
ReferenceConfig<XxxService> reference = new ReferenceConfig<XxxService>(); // This instance is heavy, encapsulates the connection to the registry and the connection to the provider, please cache it yourself, otherwise it may cause memory and connection leaks.

reference.setApplication(application);
reference.setRegistry(registry); // Multiple registries can use setRegistries()
reference.setInterface(XxxService.class);
reference.setVersion("1.0.0");

// Use xxxService like local beans
XxxService xxxService = reference.get();
    methodSpecial settings
    
// Method level configuration
List<MethodConfig> methods = new ArrayList<MethodConfig>();
MethodConfig method = new MethodConfig();
method.setName("createXxx");
method.setTimeout(10000);
method.setRetries(0);
Methods.add(method);
// reference remote service
ReferenceConfig<XxxService> reference = new ReferenceConfig<XxxService>(); // This instance is heavy, encapsulates the connection to the registry and the connection to the provider, please cache it yourself, otherwise it may cause memory and connection leaks.
...
reference.setMethods(methods); // Set method level configuration

    Consumer Calling Remote Service

    The above chapters are more from a configuration point of view, and then through a complete example, explain the complete use of dubbo consumer.

    There is only one service UserReadService in this example, there is a method getUserById. Need to call a remote service through Dubbo. The specific steps are as follows:

    1. Create a project If there is already a project, you can ignore it. Create a spring boot project that can be created at https://start.spring.io/. The provider of the service has been defined in the provider section.
    2. Call the service
    @RestController
Public class UserTestController{
    @Autowired
    Private UserReadService userReadService;
    @RequestMapping("/user/getById")
    Public String getUserById(Long id){
        // just test
        Return userReadService.getUserById(id).toString();
    }
}

    3.Dubbo configuration

    
<?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:reference id="userReadService" interface="com.package.UserReadService"check="false" />
</beans>

    Other ways of configuring Dubbo can refer to the relevant configuration in the previous section, or use the integrated dubbo spring boot starter mode.