Using Service Registry

The service center of the ServiceComb engine provides the service registry function that registers basic information, such as the application to which a microservice belongs, microservice name, microservice version, and listening address, with the service center when the microservice is started.

During microservice running, the basic information about other microservices can be queried through the service center. The registered information varies with microservice development frameworks. For example, the service contract information is registered in Java chassis. The registered basic information and the process of registering and discovering other microservices are the same for all microservice development frameworks.

This section describes how different microservice development frameworks use the service center and configure their own registry information, as well as the configuration items related to the interaction between microservices and the registry center. After a microservice is registered, you can use the ServiceComb catalog, instance list, and dependencies in CSE.

Spring Cloud

When Spring Cloud uses service registry, you need to add the following dependencies to the project:

<dependency> 
  <groupId>com.huaweicloud</groupId>  
  <artifactId>spring-cloud-starter-huawei-servicecomb-discovery</artifactId> 
</dependency>

If the dependencies have been directly or indirectly included in the project, you do not need to add them. Table 1 describes the configuration items of Spring Cloud. The values of these configuration items affect the basic information registered in the service center and the interaction between microservices and the service center, such as heartbeats. Information related to service registry needs to be configured in the bootstrap.yml file.

**Table 1** Common configuration items of Spring Cloud
Item	Description	Default Value	Remarks
spring.cloud.servicecomb.discovery.appName	Application	default	-
spring.cloud.servicecomb.discovery.serviceName	Microservice name	-	If no service name exists, use spring.application.name.
spring.cloud.servicecomb.discovery.version	Microservice version	-	-
server.env	Environment	-	The value is the environment ID. Example value: production or development.
spring.cloud.servicecomb.discovery.enabled	Whether to enable service registry and discovery	true	-
spring.cloud.servicecomb.discovery.address	Registry center address	-	Use commas (,) to separate cluster addresses.
spring.cloud.servicecomb.discovery.watch	Whether to enable the watch mode	false	-
spring.cloud.servicecomb.discovery.healthCheckInterval	Interval for sending heartbeat messages, in seconds	15	Value range: 1 ≤ configuration item ≤ 600.
spring.cloud.servicecomb.discovery.datacenter.name	Data center name	-	-
spring.cloud.servicecomb.discovery.datacenter.region	Data center region	-	-
spring.cloud.servicecomb.discovery.datacenter.availableZone	AZ of the data center	-	-
spring.cloud.servicecomb.discovery.allowCrossApp	Whether cross-application calling is supported	false	Server configuration, indicating that clients in different applications are allowed to discover themselves.

Java Chassis

When Java chassis uses service registry, you need to add the following dependencies to the project:

<dependency>
  <groupId>org.apache.servicecomb</groupId>
  <artifactId>registry-service-center</artifactId>
</dependency>

If the dependencies have been directly or indirectly included in the project, you do not need to add them. Table 2 describes the configuration items of Java chassis. The values of these configuration items affect the basic information registered in the service center and the interaction between microservices and the service center, such as heartbeats.

**Table 2** Common configuration items of Java chassis
Item	Description	Default Value	Remarks
servicecomb.service.application	Application	default	-
servicecomb.service.name	Microservice name	defaultMicroservice	-
servicecomb.service.version	Microservice version	1.0.0.0	-
servicecomb.service.environment	Environment	-	The value is the environment ID. Example value: production or development.
servicecomb.service.registry.address	Registry center address	http://127.0.0.1:30100	Use commas (,) to separate cluster addresses.
servicecomb.service.registry.instance.watch	Whether to enable the watch mode	true	-
servicecomb.service.registry.instance.healthCheck.interval	Interval for sending heartbeat messages, in seconds	30	-
servicecomb.service.registry.instance.healthCheck.times	Indicates the allowed number of heartbeat failures. If the heartbeat fails for the consecutive times+1 times, the instance is brought offline by the service center. That is, interval x (times + 1) determines the time when an instance is automatically deregistered. If the service center does not receive a heartbeat message for a long time, the service center deregisters the instance.	3	-
servicecomb.datacenter.name	Data center name	-	-
servicecomb.datacenter.region	Data center region	-	-
servicecomb.datacenter.availableZone	AZ of the data center	-	-

The instance address and listening address registered by Java chassis are related to the release address specified by servicecomb.service.publishAddress. The configuration items of the service listening address are servicecomb.rest.address and servicecomb.highway.address, which correspond to the listening addresses of the REST and highway transmission modes, respectively. Table 3 shows the relationship between the registered address, listening address, and release address.

**Table 3** Effective rules of registered instance addresses
Listening Address	Release Address	Registered Instance Address
127.0.0.1	-	127.0.0.1
0.0.0.0	-	Set it to the IP address of a NIC. The wildcard address, loopback address, or broadcast address is not selected.
Specific IP address	-	Set it to the listening address.
*	Specific IP address	Set it to the release address.
*	"{NIC name}"	Specifies the IP address corresponding to the NIC name. Note that the IP address must be enclosed in quotation marks and brackets.