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:

xml <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:

java 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:

```java 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:
• 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

   <cse:rpc-schema schema-id="pojoHello" implementation="org.apache.servicecomb.samples.pojo.provider.PojoHelloImpl"/>

```

1. Annotation configuration Mode: @RpcSchema is used to define schema during the API Hello implementation. The code is as follows:

```java 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

   <context:component-scan base-package="org.apache.servicecomb.samples.pojo.provider"/>

```

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:

```java 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(); } } ```