Develop Microservice with Transparent RPC

Concept Description

The transparent remote procedure call(RPC) development mode is a development mode based on API and API implementation. The service developer does not need to use the description of Spring MVC and JAX-RS.

Development Example

  • Step 1 Import dependencies into your maven project:

      <dependencyManagement>
       <dependencies>
         <dependency>
           <groupId>org.apache.servicecomb</groupId>
           <artifactId>java-chassis-dependencies</artifactId>
           <version>1.0.0-m1</version>
           <type>pom</type>
           <scope>import</scope>
         </dependency>
       </dependencies>
      </dependencyManagement>
      <dependencies>
        <!--transport can optional import through endpoint setting in microservice.yaml, we import both rest and highway as example-->
        <dependency>
          <groupId>org.apache.servicecomb</groupId>
          <artifactId>transport-rest-vertx</artifactId>
        </dependency>
        <dependency>
          <groupId>org.apache.servicecomb</groupId>
          <artifactId>transport-highway</artifactId>
        </dependency>
        <dependency>
          <groupId>org.apache.servicecomb</groupId>
          <artifactId>provider-pojo</artifactId>
        </dependency>
        <dependency>
          <groupId>org.slf4j</groupId>
          <artifactId>slf4j-log4j12</artifactId>
        </dependency>
      </dependencies>
    
  • Step 2 Define a service API. Compile the Java API definition based on the API definition defined before development. The code is as follows:

     public interface Hello {
       String sayHi(String name);
       String sayHello(Person person);
     }
    
  • Step 3 implement the service. The implementation of the Hello service is as follows:

     import org.apache.servicecomb.samples.common.schema.Hello;
     import org.apache.servicecomb.samples.common.schema.models.Person;
    
     public class HelloImpl implements Hello {
       @Override
       public String sayHi(String name) {
         return "Hello " + name;
       }
    
       @Override
       public String sayHello(Person person) {
         return "Hello person " + person.getName();
       }
     }
    
  • Step 4 Release the service. The transparent RPC development mode supports two service release mode: Spring XML configuration and Annotation configuration:

    1. Spring XML configuration Mode: Create the pojoHello.bean.xml file in the resources/META-INF/spring directory and declare the schema in the file. The content of the file is as follows:
     <?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:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util"
            xmlns:cse="http://www.huawei.com/schema/paas/cse/rpc"
            xmlns:context="http://www.springframework.org/schema/context"
            xsi:schemaLocation="http://www.springframework.org/schema/beans classpath:org/springframework/beans/factory/xml/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.huawei.com/schema/paas/cse/rpc classpath:META-INF/spring/spring-paas-cse-rpc.xsd">
    
         <cse:rpc-schema schema-id="pojoHello" implementation="org.apache.servicecomb.samples.pojo.provider.PojoHelloImpl"/>
     </beans>
    
  1. Annotation configuration Mode: @RpcSchema is used to define schema during the API Hello implementation. The code is as follows:

    import org.apache.servicecomb.provider.pojo.RpcSchema;
    @RpcSchema(schemaId = "pojoHello")
    public class HelloImpl implements Hello {
       @Override
       public String sayHi(String name) {
         return "Hello " + name;
       }
     
       @Override
       public String sayHello(Person person) {
         return "Hello person " + person.getName();
       }
    }
    

    In the pojoHello.bean.xml file of resources/META-INF/spring directory, configure base-package that performs scanning. The content of the file is as follows:

    <?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:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util"
           xmlns:cse="http://www.huawei.com/schema/paas/cse/rpc"
           xmlns:context="http://www.springframework.org/schema/context"
           xsi:schemaLocation="http://www.springframework.org/schema/beans classpath:org/springframework/beans/factory/xml/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.huawei.com/schema/paas/cse/rpc classpath:META-INF/spring/spring-paas-cse-rpc.xsd">
    
        <context:component-scan base-package="org.apache.servicecomb.samples.pojo.provider"/>
    </beans>
    

Note: THE PATH FOR RPC IS ClassName/MethodName, AND THE METHOD IS POST.

In this sample the Path of sayHi is /HelloImpl/sayHi, and the Path of sayHello is /HelloImpl/sayHello.

NOTE: Different from the Spring MVC and JAX-RS development modes, the transparent RPC development mode used @RpcSchema instead of @RestSchema.

  • Step 5 Add service definition file:

    Add microservice.yaml file into resources folder of your project.

  • Step 6 Add Main class:

     import org.apache.servicecomb.foundation.common.utils.BeanUtils;
     import org.apache.servicecomb.foundation.common.utils.Log4jUtils;
    
     public class Application {
       public static void main(String[] args) throws Exception {
          //initializing log, loading bean(including its parameters), and registering service, more detail can be found here : http://servicecomb.incubator.apache.org/users/application-boot-process/
          Log4jUtils.init();
          BeanUtils.init();
       }
     }