Service discovery is one of the key components in the microservices architecture. In such a architecture, configuring a service list for every client manually could be a daunting task, and makes dynamic scaling extremely difficult. Nacos Discovery helps you to register your service to the Nacos server automatically, and the Nacos server keeps track of the services and refreshes the service list dynamically. In addition, Nacos Discovery registers some of the metadata of the service instance, such as host, port, health check URL, homepage to Nacos. For details about how to download and start Nacos, refer to the Nacos Website.

please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alibaba-nacos-discovery.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>

Nacos Discovery integrate with the Netflix Ribbon, RestTemplate or OpenFeign can be used for service-to-service calls.

3.3.1 Nacos Server Startup

For details about how to download and start Nacos, refer to the Nacos Website.

After Nacos Server starts, go to http://ip:8848 to view the console (default account name/password is nacos/nacos):

Figure 3.1. Nacos Dashboard

For more Nacos Server versions, you can download the latest version from release page.

3.3.2 Start a Provider Application

The following sample illustrates how to register a service to Nacos.

• Configuration of pom.xml The following is a complete example of pom.xml:

<?xml version="1.0" encoding="UTF-8"? >
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>open.source.test</groupId>
    <artifactId>nacos-discovery-test</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>nacos-discovery-test</name>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>${spring.boot.version}</version>
        <relativePath/>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring.cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>${spring.cloud.alibaba.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

• Configuration of application.properties Some of the basic configurations of Nacos must be included in application.properties(or application.yaml), as shown below： application.properties

server.port=8081
spring.application.name=nacos-producer
spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848
management.endpoints.web.exposure.include=*

	Note
	If you do not want to use Nacos for service registration and discovery, you can set spring.cloud.nacos.discovery to false.

• The following is a sample for starting Provider:

@SpringBootApplication
@EnableDiscoveryClient
public class NacosProviderDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(NacosProducerDemoApplication.class, args);
    }

    @RestController
    public class EchoController {
        @GetMapping(value = "/echo/{string}")
        public String echo(@PathVariable String string) {
            return "Hello Nacos Discovery " + string;
        }
    }
}

Now you can see the registered services on the Nacos console.

	Note
	Before you start the provider application, please start Nacos first. Refer to Naco Website for more details.

3.3.3 Start a Consumer Application

It might not be as easy as starting a provider application, because the consumer needs to call the RESTful service of the provider. In this example, we will use the most primitive way, that is, combining the LoadBalanceClient and RestTemolate explicitly to access the RESTful service. You can refer to section 1.2 for pom.xml and application.properties configurations. The following is the sample code for starting a consumer application.

	Note
	You can also access the service by using RestTemplate and FeignClient with load balancing.

@SpringBootApplication
@EnableDiscoveryClient
public class NacosConsumerApp {

    @RestController
    public class NacosController{

        @Autowired
        private LoadBalancerClient loadBalancerClient;
        @Autowired
        private RestTemplate restTemplate;

        @Value("${spring.application.name}")
        private String appName;

        @GetMapping("/echo/app-name")
        public String echoAppName(){
            //Access through the combination of LoadBalanceClient and RestTemolate
            ServiceInstance serviceInstance = loadBalancerClient.choose("nacos-provider");
            String path = String.format("http://%s:%s/echo/%s",serviceInstance.getHost(),serviceInstance.getPort(),appName);
            System.out.println("request path:" +path);
            return restTemplate.getForObject(path,String.class);
        }

    }

    //Instantiate RestTemplate Instance
    @Bean
    public RestTemplate restTemplate(){

        return new RestTemplate();
    }

    public static void main(String[] args) {

        SpringApplication.run(NacosConsumerApp.class,args);
    }
}

In this example, we injected a LoadBalancerClient instance, and instantiated a RestTemplate manually. At the same time, we injected the configuration value of spring.application.name into the application, so that the current application name can be displayed when calling the service of the provider.

	Note
	Please start Nacos before you start the consumer application. For details, please refer to Nacos Website.

Next, access the http://ip:port/echo/app-name interface provided by the consumer. Here we started the port of 8082. The access result is shown below：

Address：http://127.0.0.1:8082/echo/app-name
Access result： Hello Nacos Discovery nacos-consumer

Nacos Discovery provides an Endpoint internally with a corresponding endpoint id of nacos-discovery.

Endpoint exposed json contains two properties:

The followings shows how a service instance accesses the Endpoint:

{
  "subscribe": [
    {
      "jsonFromServer": "",
      "name": "nacos-provider",
      "clusters": "",
      "cacheMillis": 10000,
      "hosts": [
        {
          "instanceId": "30.5.124.156#8081#DEFAULT#nacos-provider",
          "ip": "30.5.124.156",
          "port": 8081,
          "weight": 1.0,
          "healthy": true,
          "enabled": true,
          "cluster": {
            "serviceName": null,
            "name": null,
            "healthChecker": {
              "type": "TCP"
            },
            "defaultPort": 80,
            "defaultCheckPort": 80,
            "useIPPort4Check": true,
            "metadata": {

            }
          },
          "service": null,
          "metadata": {

          }
        }
      ],
      "lastRefTime": 1541755293119,
      "checksum": "e5a699c9201f5328241c178e804657e11541755293119",
      "allIPs": false,
      "key": "nacos-producer",
      "valid": true
    }
  ],
  "NacosDiscoveryProperties": {
    "serverAddr": "127.0.0.1:8848",
    "endpoint": "",
    "namespace": "",
    "logName": "",
    "service": "nacos-provider",
    "weight": 1.0,
    "clusterName": "DEFAULT",
    "metadata": {

    },
    "registerEnabled": true,
    "ip": "30.5.124.201",
    "networkInterface": "",
    "port": 8082,
    "secure": false,
    "accessKey": "",
    "secretKey": ""
  }
}

The following shows the other configurations of the starter of Nacos Discovery:

please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alibaba-nacos-config.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>

Nacos Config uses DataId and GROUP to determine a configuration.

The following figure shows that the DataId uses myDataid, GROUP uses DEFAULT_GROUP, and configures a configuration item of the format Properties:

Figure 4.1. Nacos Config Item

4.2.1 Initialize Nacos Server

For specific startup methods, refer to the "Nacos Server Startup" section of the Spring Cloud Alibaba Nacos Discovery section.

After the Nacos Server is started, add how to configure it:

Data ID:    nacos-config.properties

Group  :    DEFAULT_GROUP

Configuration format:    Properties

Configuration content:   user.name=nacos-config-properties
            user.age=90

	Note
	The default file extension of DataId is properties.

Usage on the Client

If you want to use Nacos to manage externalized configurations for your applications, please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alibaba-nacos-config.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>

Now we can create a standard Spring Boot application.

@SpringBootApplication
public class NacosConfigApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(NacosConfigApplication.class, args);
        String userName = applicationContext.getEnvironment().getProperty("user.name");
        String userAge = applicationContext.getEnvironment().getProperty("user.age");
        System.err.println("user name :" +userName+"; age: "+userAge);
    }
}

Before running this example, we need to configure the address of the Nacos server in bootstrap.properties. For example:

bootstrap.properties. 

# DataId By default, the `spring.application.name` configuration is combined with the file extension (the configuration format uses properties by default), and the GROUP is not configured to use DEFAULT_GROUP by default. Therefore, the Nacos Config configuration corresponding to the configuration file has a DataId of nacos-config.properties and a GROUP of DEFAULT_GROUP
spring.application.name=nacos-config
spring.cloud.nacos.config.server-addr=127.0.0.1:8848

	Note
	If you use domain name to access Nacos, the format of spring.cloud.nacos.config.server-addr should be Domain name:port. For example, if the Nacos domain name is abc.com.nacos, and the listerner port is 80, then the configuration should be spring.cloud.nacos.config.server-addr=abc.com.nacos:80. Port 80 cannot be omitted.

Run this example and you can see the following output:

2018-11-02 14:24:51.638  INFO 32700 --- [main] c.a.demo.provider.NacosConfigApplication    : Started NacosConfigApplication in 14.645 seconds (JVM running for 15.139)
user name :nacos-config-properties; age: 90
2018-11-02 14:24:51.688  INFO 32700 --- [-127.0.0.1:8848] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@a8c5e74: startup date [Fri Nov 02 14:24:51 CST 2018]; root of context hierarchy

Nacos Config supports yaml format as well. You only need to complete the following 2 steps.

bootstrap.properties. 

spring.cloud.nacos.config.file-extension=yaml

Data ID:        nacos-config.yaml

Group  :        DEFAULT_GROUP

Configuration format:        YAML

Configuration content:        user.name: nacos-config-yaml
                              user.age: 68

After completing the preivous two steps, restart the testing program and you will see the following result.

2018-11-02 14:59:00.484  INFO 32928 --- [main] c.a.demo.provider.NacosConfigApplication:Started NacosConfigApplication in 14.183 seconds (JVM running for 14.671)
user name :nacos-config-yaml; age: 68
2018-11-02 14:59:00.529  INFO 32928 --- [-127.0.0.1:8848] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@265a478e: startup date [Fri Nov 02 14:59:00 CST 2018]; root of context hierarchy

Nacos Config also supports dynamic configuration updates. The code for starting Spring Boot application testing is as follows:

@SpringBootApplication
public class NacosConfigApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(NacosConfigApplication.class, args);
        while(true) {
            //When configurations are refreshed dynamically, they will be updated in the Enviroment, therefore here we retrieve configurations from Environment every other second.
            String userName = applicationContext.getEnvironment().getProperty("user.name");
            String userAge = applicationContext.getEnvironment().getProperty("user.age");
            System.err.println("user name :" + userName + "; age: " + userAge);
            TimeUnit.SECONDS.sleep(1);
        }
    }
}

When user.name is changed, the latest value can be retrieved from the application, as shown below:

user name :nacos-config-yaml; age: 68
user name :nacos-config-yaml; age: 68
user name :nacos-config-yaml; age: 68
2018-11-02 15:04:25.069  INFO 32957 --- [-127.0.0.1:8848] o.s.boot.SpringApplication               : Started application in 0.144 seconds (JVM running for 71.752)
2018-11-02 15:04:25.070  INFO 32957 --- [-127.0.0.1:8848] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@10c89124: startup date [Fri Nov 02 15:04:25 CST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicationContext@6520af7
2018-11-02 15:04:25.071  INFO 32957 --- [-127.0.0.1:8848] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@6520af7: startup date [Fri Nov 02 15:04:24 CST 2018]; root of context hierarchy
//Read the updated value from Enviroment
user name :nacos-config-yaml-update; age: 68
user name :nacos-config-yaml-update; age: 68

	Note
	You can disable automatic refresh with this setting`spring.cloud.nacos.config.refresh.enabled=false`.

When configurations are loaded by Nacos Config, basic configurations with DataId of ${spring.application.name}. ${file-extension:properties} , and DataId of ${spring.application.name}-${profile}. ${file-extension:properties} are also loaded. If you need to use different configurations from different environments, you can use the ${spring.profiles.active} configuration provided by Spring.

spring.profiles.active=develop

	Note
	When specified in configuration files, ${spring.profiles.active} must be placed in bootstrap.properties.

Add a basic configuration in Nacos, with a DataId of nacos-config-develop.yaml, as shown below:

Data ID:        nacos-config-develop.yaml

Group  :        DEFAULT_GROUP

Configuration format:        YAML

Configuration content:        current.env: develop-env

Run the following Spring Boot application testing code:

@SpringBootApplication
public class NacosConfigApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(NacosConfigApplication.class, args);
        while(true) {
            String userName = applicationContext.getEnvironment().getProperty("user.name");
            String userAge = applicationContext.getEnvironment().getProperty("user.age");
            //Get the current deployment environment
            String currentEnv = applicationContext.getEnvironment().getProperty("current.env");
            System.err.println("in "+currentEnv+" enviroment; "+"user name :" + userName + "; age: " + userAge);
            TimeUnit.SECONDS.sleep(1);
        }
    }
}

After started, you can see the output as follows in the console:

in develop-env enviroment; user name :nacos-config-yaml-update; age: 68
2018-11-02 15:34:25.013  INFO 33014 --- [ Thread-11] ConfigServletWebServerApplicationContext : Closing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6f1c29b7: startup date [Fri Nov 02 15:33:57 CST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicationContext@63355449

To switch to the production environment, you only need to change the parameter of ${spring.profiles.active}. As show below:

spring.profiles.active=product

At the same time, add the basic configuration with the DataId in the Nacos of your production environment. For example, you can add the configuration with the DataId of nacos-config-product.yaml in Nacos of your production environment:

Data ID:        nacos-config-product.yaml

Group  :        DEFAULT_GROUP

Configuration format:        YAML

Configuration content:        current.env: product-env

Start the testing program and you will see the following result:

in product-env enviroment; user name :nacos-config-yaml-update; age: 68
2018-11-02 15:42:14.628  INFO 33024 --- [Thread-11] ConfigServletWebServerApplicationContext : Closing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6aa8e115: startup date [Fri Nov 02 15:42:03 CST 2018]; parent: org.springframework.context.annotation.AnnotationConfigApplicationContext@19bb07ed

	Note
	In this example, we coded the configuration in the configuration file by using the spring.profiles.active=<profilename> method. In real scenarios, this variable needs to be different in different environment. You can use the -Dspring.profiles.active=<profile> parameter to specify the configuration so that you can switch between different environments easily.

For details about namespaces in Nacos, refer to Nacos Concepts

The “Public” namespace of Nacos is used if no namespace is specified in ${spring.cloud.nacos.config.namespace}. You can also specify a custom namespace in the following way：

spring.cloud.nacos.config.namespace=b3404bc0-d7dc-4855-b519-570ed34b62d7

	Note
	This configuration must be in the bootstrap.properties file. The value of spring.cloud.nacos.config.namespace is the id of the namespace, and the value of id can be retrieved from the Nacos console. Do not select other namespaces when adding configurations. Otherwise configurations cannot be retrieved properly.

DEFAULT_GROUP is used by default when no {spring.cloud.nacos.config.group} configuration is defined. If you need to define your own group, you can define it in the following property:

spring.cloud.nacos.config.group=DEVELOP_GROUP

	Note
	This configuration must be in the bootstrap.properties file, and the value of Group must be the same with the value of spring.cloud.nacos.config.group.

As of Spring Cloud Alibaba Nacos Config, data id can be self-defined. For detailed design of this part, refer to Github issue. The following is a complete sample:

spring.application.name=opensource-service-provider
spring.cloud.nacos.config.server-addr=127.0.0.1:8848

# config external configuration
# 1. Data Id is in the default group of DEFAULT_GROUP, and dynamic refresh of configurations is not supported.
spring.cloud.nacos.config.ext-config[0].data-id=ext-config-common01.properties

# 2. Data Id is not in the default group, and dynamic refresh of configurations is not supported.
spring.cloud.nacos.config.ext-config[1].data-id=ext-config-common02.properties
spring.cloud.nacos.config.ext-config[1].group=GLOBALE_GROUP

# 3. Data Id is not in the default group and dynamic referesh of configurations is supported.
spring.cloud.nacos.config.ext-config[2].data-id=ext-config-common03.properties
spring.cloud.nacos.config.ext-config[2].group=REFRESH_GROUP
spring.cloud.nacos.config.ext-config[2].refresh=true

We can see that:

	Note
	When multiple Data Ids are configured at the same time, the priority is defined by the value of “n” in spring.cloud.nacos.config.ext-config[n].data-id. The bigger the value, the higher the priority.

	Note
	The value of spring.cloud.nacos.config.ext-config[n].data-id must have a file extension, and it could be properties or yaml/yml. The setting in spring.cloud.nacos.config.file-extension does not have any impact on the custom Data Id file extension.

The configuration of custom Data Id allows the sharing of configurations among multiple applications, and also enables support of multiple configurations for one application.

To share the data id among multiple applications in a clearer manner, you can also use the following method:

spring.cloud.nacos.config.shared-dataids=bootstrap-common.properties,all-common.properties
spring.cloud.nacos.config.refreshable-dataids=bootstrap-common.properties

We can see that:

	Note
	When using spring.cloud.nacos.config.shared-dataids to configure multiple shared data ids, we agree on the following priority between the shared configurations: Priorities are decided based on the order in which the configurations appear. The one that occurs later is higher in priority than the one that appears first.

	Note
	When using spring.cloud.nacos.config.shared-dataids, the data Id must have a file extension, and it could be properties or yaml/yml. And the configuration in spring.cloud.nacos.config.file-extension does not have any impact on the customized Data Id file extension.

	Note
	When spring.cloud.nacos.config.refreshable-dataids specifies the data ids that support dynamic refresh, the corresponding values of the data ids should also specify file extensions.

Nacos Config provides an Endpoint internally with a corresponding endpoint id of nacos-config.

Endpoint exposed json contains three properties:

The followings shows how a service instance accesses the Endpoint:

{
	"NacosConfigProperties": {
		"serverAddr": "127.0.0.1:8848",
		"encode": null,
		"group": "DEFAULT_GROUP",
		"prefix": null,
		"fileExtension": "properties",
		"timeout": 3000,
		"endpoint": null,
		"namespace": null,
		"accessKey": null,
		"secretKey": null,
		"contextPath": null,
		"clusterName": null,
		"name": null,
		"sharedDataids": "base-common.properties,common.properties",
		"refreshableDataids": "common.properties",
		"extConfig": null
	},
	"RefreshHistory": [{
		"timestamp": "2019-07-29 11:20:04",
		"dataId": "nacos-config-example.properties",
		"md5": "7d5d7f1051ff6571e2ec9f90887d9d91"
	}],
	"Sources": [{
		"lastSynced": "2019-07-29 11:19:04",
		"dataId": "common.properties"
	}, {
		"lastSynced": "2019-07-29 11:19:04",
		"dataId": "base-common.properties"
	}, {
		"lastSynced": "2019-07-29 11:19:04",
		"dataId": "nacos-config-example.properties"
	}]
}

set spring.cloud.nacos.config.enabled = false to disable Spring Cloud Nacos Config AutoConfiguration.

The following shows the other configurations of the starter of Nacos Config:

As microservices become popular, the stability of service calls is becoming increasingly important. Sentinel takes "flow" as the breakthrough point, and works on multiple fields including flow control, circuit breaking and load protection to protect service reliability.

Sentinel has the following features:

If you want to use Sentinel in your project, please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alibaba-sentinel.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

The following is a simple example of how to use Sentinel:

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(ServiceApplication.class, args);
    }

}

@RestController
public class TestController {

    @GetMapping(value = "/hello")
    @SentinelResource("hello")
    public String hello() {
        return "Hello Sentinel";
    }

}

The @SentinelResource annotation is used to identify if a resource is rate limited or degraded. In the above sample, the 'hello' attribute of the annotation refers to the resource name.

@SentinelResource also provides attributes such as blockHandler, blockHandlerClass, and fallback to identify rate limiting or degradation operations. For more details, refer to Sentinel Annotation Support.

The above examples are all used in the WebServlet environment. Sentinel currently supports WebFlux and needs to cooperate with the spring-boot-starter-webflux dependency to trigger the WebFlux-related automation configuration in sentinel starter.

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(ServiceApplication.class, args);
    }

}

@RestController
public class TestController {

    @GetMapping("/mono")
    @SentinelResource("hello")
    public Mono<String> mono() {
	return Mono.just("simple string")
			.transform(new SentinelReactorTransformer<>("otherResourceName"));
    }

}

5.2.1 Sentinel Dashboard

Sentinel dashboard is a lightweight console that provides functions such as machine discovery, single-server resource monitoring, overview of cluster resource data, as well as rule management. To use these features, you only need to complete a few steps.

Note: The statistics overview for clusters only supports clusters with less than 500 nodes, and has a latency of about 1 to 2 seconds.

Figure 5.1. Sentinel Dashboard

To use the Sentinel dashboard, simply complete the following 3 steps.

Get the Dashboard

You can download the latest dashboard JAR file from the Release Page.

You can also get the latest source code to build your own Sentinel dashboard：

• Download the Dashboard project.
• Run the following command to package the code into a FatJar: mvn clean package

Start the Dashboard

Sentinel dashboard is a standard SpringBoot application, and you can run the JAR file in the Spring Boot mode.

java -Dserver.port=8080 -Dcsp.sentinel.dashboard.server=localhost:8080 -Dproject.name=sentinel-dashboard -jar sentinel-dashboard.jar

If there is conflict with the 8080 port, you can use -Dserver.port=new port to define a new port.

spring:
  cloud:
    sentinel:
      transport:
        port: 8719
        dashboard: localhost:8080

Sentinel is compatible with the OpenFeign component. To use it, in addition to introducing the sentinel-starter dependency, complete the following 2 steps:

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

This is a simple usage of FeignClient:

@FeignClient(name = "service-provider", fallback = EchoServiceFallback.class, configuration = FeignConfiguration.class)
public interface EchoService {
    @RequestMapping(value = "/echo/{str}", method = RequestMethod.GET)
    String echo(@PathVariable("str") String str);
}

class FeignConfiguration {
    @Bean
    public EchoServiceFallback echoServiceFallback() {
        return new EchoServiceFallback();
    }
}

class EchoServiceFallback implements EchoService {
    @Override
    public String echo(@PathVariable("str") String str) {
        return "echo fallback";
    }
}

	Note
	The resource name policy in the corresponding interface of Feign is：httpmethod:protocol://requesturl. All the attributes in the @FeignClient annotation is supported by Sentinel.

The corresponding resource name of the echo method in the EchoService interface is GET:http://service-provider/echo/{str}.

Spring Cloud Alibaba Sentinel supports the protection of RestTemplate service calls using Sentinel. To do this, you need to add the @SentinelRestTemplate annotation when constructing the RestTemplate bean.

@Bean
@SentinelRestTemplate(blockHandler = "handleException", blockHandlerClass = ExceptionUtil.class)
public RestTemplate restTemplate() {
    return new RestTemplate();
}

The attribute of the @SentinelRestTemplate annotation support flow control(blockHandler, blockHandlerClass) and circuit breaking(fallback, fallbackClass).

==

The blockHandler or fallback is the static method of blockHandlerClass or fallbackClass.

The parameter and return value of method in @SentinelRestTemplate is same as org.springframework.http.client.ClientHttpRequestInterceptor#interceptor, but it has one more parameter BlockException to catch the exception by Sentinel.

The method signature of handleException in ExceptionUtil above should be like this:

public class ExceptionUtil {
    public static ClientHttpResponse handleException(HttpRequest request, byte[] body, ClientHttpRequestExecution execution, BlockException exception) {
        ...
    }
}

	Note
	When the application starts, it will check if the @SentinelRestTemplate annotation corresponding to the flow control or circuit breaking method exists, if it does not exist, it will throw an exception.

The attribute of the @SentinelRestTemplate annotation is optional.

It will return RestTemplate request block by sentinel when you using RestTemplate blocked by Sentinel. You can override it by your own logic. We provide SentinelClientHttpResponse to handle the response.

Sentinel RestTemplate provides two granularities for resource rate limiting:

	Note
	Take Http GET https://www.taobao.com/test as an example. The corresponding resource names have two levels of granularities, GET:https://www.taobao.com and GET:https://www.taobao.com/test.

SentinelProperties provide datasource attribute to configure datasource.

For example, 4 data sources are configures：

spring.cloud.sentinel.datasource.ds1.file.file=classpath: degraderule.json
spring.cloud.sentinel.datasource.ds1.file.rule-type=flow

#spring.cloud.sentinel.datasource.ds1.file.file=classpath: flowrule.json
#spring.cloud.sentinel.datasource.ds1.file.data-type=custom
#spring.cloud.sentinel.datasource.ds1.file.converter-class=JsonFlowRuleListConverter
#spring.cloud.sentinel.datasource.ds1.file.rule-type=flow

spring.cloud.sentinel.datasource.ds2.nacos.server-addr=localhost:8848
spring.cloud.sentinel.datasource.ds2.nacos.data-id=sentinel
spring.cloud.sentinel.datasource.ds2.nacos.group-id=DEFAULT_GROUP
spring.cloud.sentinel.datasource.ds2.nacos.data-type=json
spring.cloud.sentinel.datasource.ds2.nacos.rule-type=degrade

spring.cloud.sentinel.datasource.ds3.zk.path = /Sentinel-Demo/SYSTEM-CODE-DEMO-FLOW
spring.cloud.sentinel.datasource.ds3.zk.server-addr = localhost:2181
spring.cloud.sentinel.datasource.ds3.zk.rule-type=authority

spring.cloud.sentinel.datasource.ds4.apollo.namespace-name = application
spring.cloud.sentinel.datasource.ds4.apollo.flow-rules-key = sentinel
spring.cloud.sentinel.datasource.ds4.apollo.default-flow-rule-value = test
spring.cloud.sentinel.datasource.ds4.apollo.rule-type=param-flow

This method follows the configuration of Spring Cloud Stream Binder. TreeMap is used for storage internally, and comparator is String.CASE_INSENSITIVE_ORDER.

	Note
	d1, ds2, ds3, ds4 are the names of ReadableDataSource, and can be coded as you like. The file, zk, nacos , apollo refer to the specific data sources. The configurations following them are the specific configurations of these data sources respecitively.

Every data source has 3 common configuration items: data-type, converter-class and rule-type.

data-type refers to Converter. Spring Cloud Alibaba Sentinel provides two embedded values by default: json and xml (the default is json if not specified). If you do not want to use the embedded json or xml Converter, you can also fill in custom to indicate that you will define your own Converter, and then configure the converter-class. You need to specify the full path of the class for this configuration.

rule-type refers to the rule type in datasource(flow，degrade，authority，system, param-flow, gw-flow, gw-api-group).

	Note
	XML format is not supported by default. To make it effective, you need to add the jackson-dataformat-xml dependency.

To learn more about how dynamic data sources work in Sentinel, refer to Dynamic Rule Extension.

参考 Sentinel 网关限流

If you want to use Sentinel Starter with Zuul, you need to add the spring-cloud-alibaba-sentinel-gateway dependency, and you need to add the spring-cloud-starter-netflix-zuul dependency to let Zuul AutoConfiguration class in the gateway module takes effect:

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-alibaba-sentinel-gateway</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
</dependency>

参考 Sentinel 网关限流

If you want to use Sentinel Starter with Spring Cloud Gateway, you need to add the spring-cloud-alibaba-sentinel-gateway dependency and add the spring-cloud-starter-gateway dependency to let Spring Cloud Gateway AutoConfiguration class in the module takes effect:

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-alibaba-sentinel-gateway</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>

Sentinel provides an Endpoint internally with a corresponding endpoint id of sentinel.

Endpoint exposed json contains multi properties:

The followings shows how a service instance accesses the Endpoint:

{
	"blockPage": null,
	"appName": "sentinel-example",
	"consoleServer": "localhost:8080",
	"coldFactor": "3",
	"rules": {
		"flowRules": [{
			"resource": "GET:http://www.taobao.com",
			"limitApp": "default",
			"grade": 1,
			"count": 0.0,
			"strategy": 0,
			"refResource": null,
			"controlBehavior": 0,
			"warmUpPeriodSec": 10,
			"maxQueueingTimeMs": 500,
			"clusterMode": false,
			"clusterConfig": null
		}, {
			"resource": "/test",
			"limitApp": "default",
			"grade": 1,
			"count": 0.0,
			"strategy": 0,
			"refResource": null,
			"controlBehavior": 0,
			"warmUpPeriodSec": 10,
			"maxQueueingTimeMs": 500,
			"clusterMode": false,
			"clusterConfig": null
		}, {
			"resource": "/hello",
			"limitApp": "default",
			"grade": 1,
			"count": 1.0,
			"strategy": 0,
			"refResource": null,
			"controlBehavior": 0,
			"warmUpPeriodSec": 10,
			"maxQueueingTimeMs": 500,
			"clusterMode": false,
			"clusterConfig": null
		}]
	},
	"metricsFileCharset": "UTF-8",
	"filter": {
		"order": -2147483648,
		"urlPatterns": ["/*"],
		"enabled": true
	},
	"totalMetricsFileCount": 6,
	"datasource": {
		"ds1": {
			"file": {
				"dataType": "json",
				"ruleType": "FLOW",
				"converterClass": null,
				"file": "...",
				"charset": "utf-8",
				"recommendRefreshMs": 3000,
				"bufSize": 1048576
			},
			"nacos": null,
			"zk": null,
			"apollo": null,
			"redis": null
		}
	},
	"clientIp": "30.5.121.91",
	"clientPort": "8719",
	"logUsePid": false,
	"metricsFileSize": 52428800,
	"logDir": "...",
	"heartbeatIntervalMs": 10000
}

The following table shows that when there are corresponding bean types in ApplicationContext, some actions will be taken:

The following table shows all the configurations of Spring Cloud Alibaba Sentinel:

	Note
	These configurations will only take effect in servlet environment. RestTemplate and Feign will not take effect for these configurations.

Dubbo Spring Cloud is based on Dubbo Spring Boot 2.7.3[1] and Spring Cloud 2.x development, whether the developer is a Dubbo user or a Spring Cloud user. Easily navigate and move apps up at a cost close to “zero” costs. Dubbo Spring Cloud is designed to simplify Cloud Native development costs, improve R&D performance, and improve application performance.

Since Dubbo Spring Cloud is built on top of the native Spring Cloud, its service governance capabilities are considered Spring Cloud Plus. Not only does it fully cover the Spring Cloud native features [5], but it also provides a more stable and mature implementation, as shown in the following table:

[1]: Starting with 2.7.0, Dubbo Spring Boot and Dubbo are consistent in version

[2]: Preview releases of Spring Cloud Alibaba are available: 0.9.0, 0.2.2, and 0.1.2 - https://spring.io/blog/2011/04/11/preview-releases-of-spring-cloud-alibaba-are-available-0-9-0-0-2-2-and-0-1-2

[3]: The current version of the Spring Cloud "F" is: Finchley.SR2 - https://cloud.spring.io/spring-cloud-static/Finchley.SR2/single/spring-cloud.html

[4]: The current Spring Cloud "G" version is Greenwich.RELEASE

[5]: Spring Cloud feature list - https://cloud.spring.io/spring-cloud-static/Greenwich.RELEASE/single/spring-cloud.html#_features

[6]: Dubbo 2.7 starts supporting the configuration center and can be customized - http://dubbo.apache.org/en-us/docs/user/configuration/config-center.html

[7]: Spring Cloud native registry, in addition to Eureka, Zookeeper, and Consul, includes Nacos in Spring Cloud Alibaba

[8]: Dubbo Native Registration Center - http://dubbo.apache.org/en-us/docs/user/references/registry/introduction.html

[9]: Alibaba Sentinel: Sentinel uses traffic as an entry point to protect service stability from multiple dimensions such as flow control, blowdown, and system load protection - https://github.com/alibaba/Sentinel/wiki/%E4%BB%8B %E7%BB%8D, currently Sentinel has been accepted as a candidate for Circuit Breaker by the Spring Cloud project - https://spring.io/blog/2011/04/8/introducing-spring-cloud-circuit-breaker

[10]:Spring Cloud Sleuth - https://spring.io/projects/spring-cloud-sleuth

[11]: Zipkin - https://github.com/apache/incubator-zipkin

RocketMQ is an open-source distributed message system. It is based on highly available distributed cluster technologies and provides message publishing and subscription service with low latency and high stability. RocketMQ is widely used in a variety of industries, such as decoupling of asynchronous communication, enterprise sulotions, financial settlements, telecommunication, e-commerce, logistics, marketing, social media, instant messaging, mobile applications, mobile games, vedios, IoT, and Internet of Vehicles.

It has the following features:

Download Latest Binary File of RocketMQ, and decompress it.

The decompressed directory is as follows:

apache-rocketmq
├── LICENSE
├── NOTICE
├── README.md
├── benchmark
├── bin
├── conf
└── lib

nohup sh bin/mqnamesrv &
tail -f ~/logs/rocketmqlogs/namesrv.log

nohup sh bin/mqbroker -n localhost:9876 &
tail -f ~/logs/rocketmqlogs/broker.log

Send messages:

sh bin/tools.sh org.apache.rocketmq.example.quickstart.Producer

Output when the message is successfuly sent: SendResult [sendStatus=SEND_OK, msgId= …​

Receive messages:

sh bin/tools.sh org.apache.rocketmq.example.quickstart.Consumer

Output when the message is successfully received： ConsumeMessageThread_%d Receive New Messages: [MessageExt…​

sh bin/mqshutdown broker
sh bin/mqshutdown namesrv

Spring Cloud Stream is a microservice framework used to build architectures based on messages. It helps you to create production-ready single-server Spring applications based on SpringBoot, and connects with Broker using Spring Integration.

Spring Cloud Stream provides unified abstractions of message middleware configurations, and puts forward concepts such as publish-subscribe, consumer groups and partition.

There are two concepts in Spring Cloud Stream: Binder and Binding

For example, Kafka uses KafkaMessageChannelBinder, RabbitMQ uses RabbitMessageChannelBinder, while RocketMQ uses RocketMQMessageChannelBinder.

Binding serves as a bridge between message middleware and the provider and consumer of the applications. Developers only need to use the Provider or Consumer to produce or consume data, and do not need to worry about the interactions with the message middleware.

Figure 7.1. Spring Cloud Stream

Now let’s use Spring Cloud Stream to write a simple code for sending and receiving messages:

MessageChannel messageChannel = new DirectChannel();

// Message subscription
((SubscribableChannel) messageChannel).subscribe(new MessageHandler() {
    @Override
    public void handleMessage(Message<? > message) throws MessagingException {
        System.out.println("receive msg: " + message.getPayload());
    }
});

// Message sending
messageChannel.send(MessageBuilder.withPayload("simple msg").build());

All the message types in this code are provided by the `spring-messaging`module. It shields the lower-layer implementations of message middleware. If you would like to change the message middleware, you only need to configure the related message middleware information in the configuration file and modify the binder dependency.

The lower layer of Spring Cloud Stream also implements various code abstractions based on the previous code.

For using the Spring Cloud Alibaba RocketMQ Binder, you just need to add it to your Spring Cloud Stream application, using the following Maven coordinates:

<dependency>
  <groupId>com.alibaba.cloud</groupId>
  <artifactId>spring-cloud-stream-binder-rocketmq</artifactId>
</dependency>

Alternatively, you can also use the Spring Cloud Stream RocketMQ Starter:

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-stream-rocketmq</artifactId>
</dependency>

This is the implementation architecture of Spring Cloud Stream RocketMQ Binder:

Figure 7.2. SCS RocketMQ Binder

The implementation of RocketMQ Binder depend on the RocketMQ-Spring framework.

RocketMQ Spring framework is an integration of RocketMQ and Spring Boot. It provides three main features:

RocketMQMessageChannelBinder is a standard implementation of Binder, it will build RocketMQInboundChannelAdapter and RocketMQMessageHandler internally.

RocketMQMessageHandler will construct RocketMQTemplate based on the Binding configuration. RocketMQTemplate will convert the org.springframework.messaging.Message message class of spring-messaging module to the RocketMQ message class org.apache.rocketmq.common .message.Message internally, then send it out.

RocketMQInboundChannelAdapter will also construct RocketMQListenerBindingContainer based on the Binding configuration, and RocketMQListenerBindingContainer will start the RocketMQ Consumer to receive the messages.

	Note
	RocketMQ Binder Application can also be used to configure rocketmq.** to trigger RocketMQ Spring related AutoConfiguration

Currently Binder supports setting the relevant key in Header to set the properties of the RocketMQ message.

For example, TAGS, DELAY, TRANSACTIONAL_ARG, KEYS, WAIT_STORE_MSG_OK, FLAG represent the labels corresponding to the RocketMQ message.

MessageBuilder builder = MessageBuilder.withPayload(msg)
    .setHeader(RocketMQHeaders.TAGS, "binder")
    .setHeader(RocketMQHeaders.KEYS, "my-key")
    .setHeader("DELAY", "1");
Message message = builder.build();
output().send(message);

SCS RocketMQ Binder support MessageSource，which can receive messages by pull mode：

@SpringBootApplication
@EnableBinding(MQApplication.PolledProcessor.class)
public class MQApplication {

  private final Logger logger =
  	  LoggerFactory.getLogger(MQApplication.class);

  public static void main(String[] args) {
    SpringApplication.run(MQApplication.class, args);
  }

  @Bean
  public ApplicationRunner runner(PollableMessageSource source,
  	    MessageChannel dest) {
    return args -> {
      while (true) {
        boolean result = source.poll(m -> {
          String payload = (String) m.getPayload();
          logger.info("Received: " + payload);
          dest.send(MessageBuilder.withPayload(payload.toUpperCase())
              .copyHeaders(m.getHeaders())
              .build());
        }, new ParameterizedTypeReference<String>() { });
        if (result) {
          logger.info("Processed a message");
        }
        else {
          logger.info("Nothing to do");
        }
        Thread.sleep(5_000);
      }
    };
  }

  public static interface PolledProcessor {

    @Input
    PollableMessageSource source();

    @Output
    MessageChannel dest();

  }

}

If you want to use ANS in your project, please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alicloud-ans.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alicloud-ans</artifactId>
</dependency>

When Spring Cloud AliCloud ANS Starter is introduced on the client, the metadata of the service such as IP, port number and weright will be registered to the registration center automatically. The client will maintain heartbeat with the server to prove that it is capable of providing service properly.

The following is a simple illustration.

@SpringBootApplication
@EnableDiscoveryClient
@RestController
public class ProviderApplication {

    @RequestMapping("/")
    public String home() {
        return "Hello world";
    }

    public static void main(String[] args) {
        SpringApplication.run(ProviderApplication.class, args);
    }

}

As the service will registered to the registration center, we will need to configure the address of the registration center. We also need to add the following address in application.properties.

# The application name will be used as the service name, therefore it is mandatory.
spring.application.name=ans-provider
server.port=18081
# The following is the IP and port number of the registration center.
spring.cloud.alicloud.ans.server-list=127.0.0.1
spring.cloud.alicloud.ans.server-port=8080

	Note
	By now the registration center is not started yet, so you will get an error message if your application is started. Therefore, start the registration center before you start your application.

ANS uses two types of registration centers. One is the free lightweight configuration center and the other is the registration center on cloud, which is provided through EDAS. Generally, you can use the lightweight version for application development and local testing, and use EDAS for canary deployment or production.

8.3.1 Start Lightweight Configuration Center

Refer to the Configure Lightweight Configuration Center for details about how to download and install lightweight configuration center.

	Note
	You only need to perform step 1(Download lightweight configuration center) and step 2(Start lightweight configuration center). Step 3(Configure hosts) is not required if you use ANS at the same time.

After you start the lightweight configuration center, start ProviderApplication directly, and you will be able to register your service to the configuration center. The default port of the lightweight configuration center is 8080, therefore you can open http://127.0.0.1:8080, click “Services” on the left and see the registered service.

8.3.2 User Registration Center on the Cloud

Using the registration center on the cloud saves you from the tedious work of server maintenance while at the same time provides a better stability. There is no difference at the code level between using the registration center on cloud and lightweight configuration center, but there are some differences in configurations.

The following is a simple sample of using the registration center on the cloud.

# The application name will be used the service name, and is therefore mandatory.
spring.application.name=ans-provider
# Configure your own port number
server.port=18081
# The following is the IP and port number of the configuration center. The default value is 127.0.0.1 and 8080, so the following lines can be omitted.
spring.cloud.alicloud.ans.server-mode=EDAS
spring.cloud.alicloud.access-key=Your Alibaba Cloud AK
spring.cloud.alicloud.secret-key=Your Alibaba Cloud SK
spring.cloud.alicloud.edas.namespace=cn-xxxxx

The default value of server-mode is LOCAL. If you want to use the registration center on cloud, you need to change it to EDAS.

Access-key and secret-key are the AK/SK of your Alibaba Cloud account. Register an Alibaba Cloud account first and log on to the Cloud Console Alibaba Cloud AK/SK to copy your AccessKey ID and Access Key Secret. If you haven’t created one, click the “Create AccessKey” button.

Namespace is a concept in EDAS, which is used to isolate environments, such as testing environment and production environment. To find your namespace, click to Sign up for EDAS first. You will not be charged under the pay-as-you-go mode. Then log on to the EDAS Console and you will be able to see your namespace, for example cn-hangzhou.

	Note
	EDAS provides application hosting service and will fill in all configurations automatically for the hosted applications.

If you want to use ACM in your project, please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alicloud-acm.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alicloud-acm</artifactId>
</dependency>

When Spring Cloud Alibaba Cloud ACM Starter is introduced into the client, the application will automatically get configuration information from the configuration management server when it starts, and inject the configuration into Spring Environment.

The following is a simple illustration.

@SpringBootApplication
public class ProviderApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(ProviderApplication.class, args);
        String userName = applicationContext.getEnvironment().getProperty("user.name");
        String userAge = applicationContext.getEnvironment().getProperty("user.age");
        System.err.println("user name :" +userName+"; age: "+userAge);
    }
}

As we need to obtain configuration information from the configuration server, we will need to configure the address of the server. We also need to add the following information in bootstrap.properties.

# Required. The application name will be used as part of the keyword to get the configuration key from the server.
spring.application.name=acm-config
server.port=18081
# The following is the IP and port number of the configuration server.
spring.cloud.alicloud.acm.server-list=127.0.0.1
spring.cloud.alicloud.acm.server-port=8080

	Note
	By now the configuration center is not started yet, so you will get an error message if your application is started. Therefore, start the configuration center before you start your application.

9.2.1 Start Configuration Center

ACM uses two types of configuration centers. One is lightweight configuration center, the other is ACM which is used on Alibaba Cloud. Generally, you can use the lightweight version for application development and local testing, and use ACM for canary deployment or production.

Use Lightweight Configuration Center

Refer to the Configure Lightweight Configuration Center for details about how to download and install lightweight configuration center.

	Note
	You only need to perform step 1(Download lightweight configuration center) and step 2(Start lightweight configuration center).

Use ACM on the Alibaba Cloud

Using ACM on the cloud saves you from the tedious work of server maintenance while at the same time provides a better stability. There is no difference at the code level between using ACM on cloud and lightweight configuration center, but there are some differences in configurations.

The following is a simple sample of using ACM. You can view configuration details on ACM Console

# The application name will be used as part of the keyword to obtain configuration key from the server, and is mandatory.
spring.application.name=acm-config
# Configure your own port number
server.port=18081
# The following is the IP and port number of the configuration center.
spring.cloud.alicloud.acm.server-mode=EDAS
spring.cloud.alicloud.access-key=Your Alibaba Cloud AK
spring.cloud.alicloud.secret-key=Your Alibaba Cloud SK
spring.cloud.alicloud.acm.endpoint=acm.aliyun.com
spring.cloud.alicloud.acm.namespace=Your ACM namespace(You can find the namespace on the ACM console)

	Note
	EDAS provides application hosting service and will fill in all configurations about ACM automatically for the hosted applications.

9.2.2 Add Configuration in the Configuration Center

1. After you start the lightweight configuration center, add the following configuration on the console.

Group:      DEFAULT_GROOUP

DataId:     acm-config.properties

Content:    user.name=james
            user.age=18

	Note
	The format of dataId is {prefix}. {file-extension}. “prefix” is obtained from spring.application.name by default, and the value of “file-extension” is "properties” by default.

user name :james; age: 18

The default file extension of dataId in spring-cloud-starter-alicloud-acm is properties. In addition to properties, yaml is also supported. You can set the file extension using spring.cloud.alicloud.acm.file-extension. Just set it to yaml or `yml`for yaml format.

	Note
	After you change the file extension, you need to make corresponding format changes in the DataID and content of the configuration center.

spring-cloud-starter-alicloud-acm supports dynamic configuration updates. RefreshEvent in Spring is published when you update configuration in the configuration center. All classes with @RefreshScope and @ConfigurationProperties annotations will be refreshed automatically.

	Note
	You can disable automatic refresh by this setting: spring.cloud.alicloud.acm.refresh.enabled=false

When configuration is loaded by spring-cloud-starter-alicloud-acm, configuration with DataId {spring.application.name}. {file-extension} will be loaded first. If there is content in spring.profiles.active, the content of spring.profile, and configuration with the dataid format of{spring.application.name}-{profile}. {file-extension} will also be loaded in turn, and the latter has higher priority.

spring.profiles.active is the configuration metadata, and should also be configured in bootstrap.properties or bootstrap.yaml. For example, you can add the following content in bootstrap.properties.

spring.profiles.active={profile-name}

Note: You can also configure the granularity through JVM parameters such as -Dspring.profiles.active=develop or --spring.profiles.active=develop, which have higher priority. Just follow the specifications of Spring Boot.

the default timeout of ACM client get config from sever is 3000 ms . If you need to define a timeout, set configuration spring.cloud.alicloud.acm.timeout,the unit is millisecond.

DEFAULT_GROUP is used by default when no {spring.cloud.alicloud.acm.group} configuration is defined. If you need to define your own group, you can use the following method:

spring.cloud.alicloud.acm.group=DEVELOP_GROUP

	Note
	This configuration must be placed in the bootstrap.properties file, and the value of Group must be the same with the value of spring.cloud.alicloud.acm.group.

9.7.1 Support Shared Configurations

ACM provides a solution to share the same configuration across multiple applications. You can do this by adding the spring.application.group configuration in Bootstrap.

spring.application.group=company.department.team

Then, you application will retrieve configurations from the following DataId in turn before it retrieves its own configuration: company:application.properties, company.department:application.properties, company.department.team:application.properties. After that, it also retrieves configuration from {spring.application.group}: {spring.application.name}. {file-extension} The later in order, the higer the priority, and the unique configuration of the application itself has the highest priority.

	Note
	The default suffix of DataId is properties, and you can change it using spring.cloud.alicloud.acm.file-extension. {spring.application.group}: {spring.application.name}. {file-extension} .

	Note
	If you configured spring.profiles.active , then the DataId format of {spring.application.group}: {spring.application.name}-{spring.profiles.active}. {file-extension} is also supported, and has higher priority than {spring.application.group}: {spring.application.name}. {file-extension}

the Actuator endpoint of ACM is /acm, config represents the ACM metadata configuration information, runtime.sources corresponds to the configuration information obtained from the ACM server and the last refresh time, runtime.refreshHistory corresponds to the dynamic refresh history.

We’ve released Spring Cloud Alibaba version 0.2.1. You will need to add dependency management POM first.

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-alibaba-dependencies</artifactId>
            <version>0.2.2.BUILD-SNAPSHOT</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

Next we need to introduce Spring Cloud Alibaba Cloud OSS Starter.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alicloud-oss</artifactId>
</dependency>

Spring Cloud Alibaba Cloud OSS integrates the Resource of the Spring framework, which allows you to use the OSS resources easily.

The following is a simple example of how to use Resource.

@SpringBootApplication
public class OssApplication {

    @Value("oss://bucketName/fileName")
    private Resource file;

    @GetMapping("/file")
    public String fileResource() {
        try {
            return "get file resource success. content: " + StreamUtils.copyToString(
                file.getInputStream(), Charset.forName(CharEncoding.UTF_8));
        } catch (Exception e) {
            return "get resource fail: " + e.getMessage();
        }
    }

    public static void main(String[] args) throws URISyntaxException {
        SpringApplication.run(OssApplication.class, args);
    }

}

	Note
	A prerequisite for the above sample is that you need to have a bucket named “bucketName” on OSS, and you have a file named “fileName” in this bucket.

In addition to AccessKeys, Spring Cloud Alibaba Cloud OSS also supports STS authentication. STS is an authentication method with temporary security tokens, and is usually used for a third party to access its resources temporarily.

For a third party to access resources temporarily, it only needs to complete the following configurations.

spring.cloud.alicloud.oss.authorization-mode=STS
spring.cloud.alicloud.oss.endpoint=***.aliyuncs.com
spring.cloud.alicloud.oss.sts.access-key=Your authenticated AK
spring.cloud.alicloud.oss.sts.secret-key=Your authenticated SK
spring.cloud.alicloud.oss.sts.security-token=Your authenticated ST

Among which, spring.cloud.alicloud.oss.authorization-mode is the enumeration type. Fill in STS here means that STS authentication is used. For endpoint information, refer to the OSS Documentation and fill in the endpoint for your region.

Access-key, secret-key and the security-token need to be issued by the authentication side. For more information about STS, refer to STS Documentation.

In addition to basic configurations, Spring Cloud Alibaba Cloud OSS also supports many other configurations, which are also included in the application.properties file.

Here are some examples.

spring.cloud.alicloud.oss.authorization-mode=STS
spring.cloud.alicloud.oss.endpoint=***.aliyuncs.com
spring.cloud.alicloud.oss.sts.access-key=Your authenticated AK
spring.cloud.alicloud.oss.sts.secret-key=Your authenticated SK
spring.cloud.alicloud.oss.sts.security-token=Your authenticated ST

spring.cloud.alicloud.oss.config.connection-timeout=3000
spring.cloud.alicloud.oss.config.max-connections=1000

For more configurations, refer to the table at the bottom of OSSClient Configurations.

	Note
	In most cases, you need to connect the parameter names with “-” for the parameters in the table of OSSClient Configurations with “-”, and all letters should be in lowercase. For example, ConnectionTimeout should be changed to connection-timeout.

If you want to use SchedulerX in your project, please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alicloud-schedulerX.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alicloud-schedulerX</artifactId>
</dependency>

After Spring Cloud Alibaba Cloud SchedulerX Starter is introduced into the client, you only need to complete a few simple configurations and you will be able to initialize the SchedulerX service automatically.

The following is a simple example.

@SpringBootApplication
public class ScxApplication {

    public static void main(String[] args) {
        SpringApplication.run(ScxApplication.class, args);
    }

}

Add the following configurations in the application.properties file.

server.port=18033
# cn-test is the test region of SchedulerX
spring.cloud.alicloud.scx.group-id=***
spring.cloud.alicloud.edas.namespace=cn-test

Before getting the group-id, please Register an Alibaba Cloud account, and then Sign up for EDAS and Sign up for SchedulerX as well.

To get the group-id, refer to the SchedulerX Documentation.

	Note
	When you create a group, please select the “test” region.

Simple job is the most commonly used job type. You only need to implement the ScxSimpleJobProcessor interface.

The following is a sample of a simple single-server job.

public class SimpleTask implements ScxSimpleJobProcessor {

	@Override
	public ProcessResult process(ScxSimpleJobContext context) {
		System.out.println("-----------Hello world---------------");
		ProcessResult processResult = new ProcessResult(true);
		return processResult;
	}

}

Go to the SchedulerX Jobs page, select the “Test” region, and click “Create Job” on the upper-right corner to create a job, as shown below.

Job Group： Test——***-*-*-****
Job process interface：SimpleTask
Type： Simple Single-Server Job
Quartz Cron Expression： Default Option——0 * * * * ?
Job Description： Empty
Custom Parameters： Empty

The job above is a “Simple Single-Server Job”, and speficied a Cron expression of "0 * * * * ?" . This means that the job will be executed once and once only in every minute.

For more job types, refer to SchedulerX Documentation.

The previous examples shows how to use SchedulerX in the “Test” region, which is mainly used for local testing.

At the production level, you need to complete some other configurations in addition to the group-id and namespace as mentioned above. See examples below:

server.port=18033
# cn-test is the test region of SchedulerX
spring.cloud.alicloud.scx.group-id=***
spring.cloud.alicloud.edas.namespace=***
# If your application runs on EDAS, you do not need to configure the following.
spring.cloud.alicloud.access-key=***
spring.cloud.alicloud.secret-key=***
# The following configurations are not mandatory. You can refer to the SchedulerX documentation for details.
spring.cloud.alicloud.scx.domain-name=***

The way to get the group-id is the same as described in the previous examples, and you can get the namespace by clicking “Namespaces” in the left-side navigation pane of the EDAS console.

	Note
	Group-id must be created within a namespace.

Access-key and secret-key are the AK/SK of your Alibaba Cloud account. If you deploy you applications on EDAS, then you do not need to fill in this information. Otherwise please go to Security Information to get your AccessKeys.

Domain-name is not mandatory. You can refer to SchedulerX Documentation for details.

If you want to use SMS in your project, please use the starter with the group ID as com.alibaba.cloud and the artifact ID as spring-cloud-starter-alicloud-sms.

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alicloud-sms</artifactId>
</dependency>

In order to reduce the cost of learning, the API interface of the Spring Cloud Alicloud SMS package is kept as consistent as the API and Example provided by the official website.

Refer to the following example to quickly develop a feature with bulk SMS sending. Add the following code in the Controller or create a new Controller:

@RequestMapping("/batch-sms-send.do")
public SendBatchSmsResponse batchsendCheckCode(
        @RequestParam(name = "code") String code) {
    SendBatchSmsRequest request = new SendBatchSmsRequest();
    request.setMethod(MethodType.GET);
    request.setPhoneNumberJson("[\"177********\",\"130********\"]");
    request.setSignNameJson("[\"*******\",\"*******\"]");
    request.setTemplateCode("******");
    request.setTemplateParamJson(
            "[{\"code\":\"" + code + "\"},{\"code\":\"" + code + "\"}]");
    SendBatchSmsResponse sendSmsResponse ;
    try {
        sendSmsResponse = smsService
                .sendSmsBatchRequest(request);
        return sendSmsResponse;
    }
    catch (ClientException e) {
        e.printStackTrace();
        sendSmsResponse =  new SendBatchSmsResponse();
    }
    return sendSmsResponse ;
}

	Note
	The MethodType of the request is set to GET, which is somewhat different from the example given by the official website. This is because the inconsistent version of the dependent Alibaba Cloud POP API version causes incompatibility issues, set to GET.

More parameter descriptions can be reference here

Refer to the following example to quickly develop a history of sending SMS messages based on a specified number. Add the following code in the Controller or create a new Controller:

@RequestMapping("/query.do")
public QuerySendDetailsResponse querySendDetailsResponse(
        @RequestParam(name = "tel") String telephone) {
    QuerySendDetailsRequest request = new QuerySendDetailsRequest();
    request.setPhoneNumber(telephone);
    request.setSendDate("20190103");
    request.setPageSize(10L);
    request.setCurrentPage(1L);
    try {
        QuerySendDetailsResponse response = smsService.querySendDetails(request);
        return response;
    }
    catch (ClientException e) {
        e.printStackTrace();
    }

    return new QuerySendDetailsResponse();
}

More parameter descriptions can be found at reference here

By subscribing to the SmsReport SMS status report, you can know the status of each SMS message and whether it knows the status and related information of the terminal user. These efforts have been encapsulated internally by Spring Cloud AliCloud SMS. You only need to complete the following two steps.

1、Configure the queue name for SmsReport in the application.properties configuration file (which can also be application.yaml).

application.properties. 

spring.cloud.alicloud.sms.report-queue-name=Alicom-Queue-********-SmsReport

2、Implement the SmsReportMessageListener interface and initialize a Spring Bean.

@Component
public class SmsReportMessageListener
		implements SmsReportMessageListener {

	@Override
	public boolean dealMessage(Message message) {
	    //do something
		System.err.println(this.getClass().getName() + "; " + message.toString());
		return true;
	}
}

More message body format for Message can be reference here.

By subscribing to the SmsUp upstream SMS message, you can know the content of the end user replying to the SMS. These efforts have also been packaged by Spring Cloud AliCloud SMS. You only need to complete the following two steps.

1、Configure the queue name for SmsReport in the application.properties configuration file (which can also be application.yaml).

application.properties. 

spring.cloud.alicloud.sms.up-queue-name=Alicom-Queue-********-SmsUp

2、Implement the SmsUpMessageListener interface and initialize a Spring Bean.

@Component
public class SmsUpMessageListener
		implements org.springframework.cloud.alicloud.sms.SmsUpMessageListener {

	@Override
	public boolean dealMessage(Message message) {
    	//do something
		System.err.println(this.getClass().getName() + "; " + message.toString());
		return true;
	}
}

More message body format for Message can be reference here.