Package alma.acs.callbacks

Sample code for the acs-callbacks support package

See: Description

Class Summary

Class	Description
Objects	Defines several helper classes.
Objects.CBdoubleImpl
Objects.CBdoubleSeqImpl
Objects.CBlongImpl
Objects.CBlongSeqImpl
Objects.CBstringImpl
Objects.CBstringSeqImpl
Objects.MyAcsJCompletion	Only necessary because the constructors in that AcsJCompletion class are protected
RequesterUtil
ResponderUtil
ResponseReceiver<T>	User should override the handler methods as needed.

Exception Summary

Exception	Description
Objects.MyAcsJException	Wraps an arbitrary Throwable in an AcsJException.

Package alma.acs.callbacks Description

Sample code for the acs-callbacks support package

The following examples show how to use the helper classes

• RequesterUtil
• ResponderUtil
• ResponseReceiver
  

I. The client requesting the server to call it back later

Class DemoRequester wants to invoke method revertString(), which demands a String, a CBstring, and a DescIn as its arguments. The latter two can/should be created using the RequesterUtil class. For CBstring to be created, a ResponseReceiver is necessary. A simple but in many cases sufficient example of an ResponseReceiver instance is shown below. When the Responder implementation calls the client back, the specified ResponseReceiver will be executed.

import java.util.logging.Logger;

import alma.acs.callbacks.RequesterUtil;
import alma.acs.callbacks.ResponseReceiver;
import alma.acs.commandcenter.meta.Firestarter;
import alma.acs.container.ContainerServicesBase;

import alma.mysubsystem.Responder;


public class DemoRequester {

    void go () throws Exception {

        // --- connect to component

        Firestarter.configure(null, "te1.hq.eso.org", "3500");
        Firestarter.prepare();
        ContainerServicesBase cs = Firestarter.giveContainerServices();
        Logger logger = cs.getLogger();

        Responder responder = ResponderHelper.narrow(cs.getComponent("RESPONDER"));

        // --- activate callback object
        
        ResponseReceiver rere  =  new ResponseReceiver() {
        
              public void incomingResponse(Object x) {
                 System.out.println("Incoming Response: "+x);
              }
              public void incomingException(Exception x) {
                 System.out.println("Responding failed: "+x);}
         
        };
        
        responder.revertString(  "Hallo",
                                 RequesterUtil.giveCBString(cs, rere), 
                                 RequesterUtil.giveDescIn()  );


        // --- do something else until response comes in
        
        System.out.println("--> press enter to exit <--");
        while (System.in.read() != 13)
            ;

        
        // --- clean up and quit
        
        Firestarter.godown();

    }
}

II. The server processing the request and afterwards calling back the client

Class EasyResponderImpl implements the revertString() method: after calculating the return value, it uses ResponderUtil to call the client back.

import alma.ACS.CBDescIn;
import alma.ACS.CBstring;
import alma.acs.component.ComponentImplBase;
import alma.acs.callbacks.ResponderUtil;

import alma.mysubsystem.ResponderOperations;


public class EasyResponderImpl extends ComponentImplBase implements ResponderOperations {


  public void revertString (String text, CBstring cb, CBDescIn descIn)  {

      try {

         // --- calculate returnvalue

         int length = text.length();
         char[] res = new char[length];
         for (int i=0; i<length; res[i] = text.charAt(length-1-i++));
         String returnValue = new String(res);

  
         // --- invoke callback
         
         ResponderUtil.respond (returnValue, cb, descIn);


      } catch (Exception exc) {
     
         ResponderUtil.respond (exc, cb, descIn);
      }
  
  }
 
}

M.Schilling, 2004-10-26