ServiceComb support users to define a customized handler and and invoke the handler in handler chain.

• Customize a handler by implement Handler interface, for example:

  public class MyHandler implements Handler {
    private static final Logger LOGGER = LoggerFactory.getLogger(MyHandler.class);
    @Override
    public void handle(Invocation invocation, AsyncResponse asyncResponse) throws Exception {
      //code before
      LOGGER.info("It's my handler! \r\n");
      invocation.next(response -> {
        // code after
        asyncResponse.handle(response);
      });
    }
  }

• Define handler id and class in cse.handler.xml config item under resources/config directory

  <config>
      <handler id="myhandler" 		     class="org.apache.servicecomb.samples.customerhandler.handlers.MyHandler" />
  </config>
  

  NOTICE: can use a different name other than cse.handler.xml, e.g. userDefined.hanlder.xml

• Configure customized MyHandler in microservice.yaml file along with other handler together

  servicecomb:
    # other configurations omitted
    handler:
      chain:
        Consumer:
          default: bizkeeper-consumer,loadbalance, myhandler

see Precondition

1. Start the ServiceComb/Service Center

   • how to start the service center
   • make sure service center address is configured correctly in microservice.yaml file

servicecomb:
 service:
   registry:
     address: http://127.0.0.1:30100		#service center address

2. Start the custom-handler-provider service

   • Start provider service by maven

     Compile the source code, and use mvn exec to execute the main class CustomHandlerProviderMain.

     mvn clean install
     cd custom-handler-sample/custom-handler-provider/
     mvn exec:java -Dexec.mainClass="org.apache.servicecomb.samples.customerhandler.provider.CustomHandlerProviderMain"

   • Start provider service by IDE

     Import the project by InteliJ IDEA or Eclipse, then find main function CustomHandlerProviderMain of provider service and RUN it like any other Java program.

3. Start the custom-handler-consumer service

   Just like how to start custom-handler-provider service. But the main class of custom-handler-consumer service is CustomHandlerCustomerMain.

   cd custom-handler-sample/custom-handler-consumer
   mvn exec:java -Dexec.mainClass="org.apache.servicecomb.samples.customerhandler.consumer.CustomHandlerCustomerMain"

4. How to verify On the producer side, the output should contain the following stuffs if the producer starts up successfully:

   1. 'swagger: 2.0 info: version: 1.0.0 ...' means the producer generated swagger contracts
   2. 'rest listen success. address=0.0.0.0:8080' means the rest endpoint is listening on port 8080

   On the consumer side, you can see the following outputs:

   1. 'It's my handler!' means custom handler had take effect