Using RMI with Client-Side Callbacks

/* Copyright (c) 1999 BEA Systems, Inc.   All Rights Reserved */

import java.rmi.*;

/**
 *  CallbackClientIntf interface contains following methods 
 *  IsGoodObject(Obj, Obj): compare 2 objects,
 *  IsRightValue(long, long): compare 2 longs,
 */
public interface CallbackClientIntf extends Remote 
{   
  public static final String NAME = "CallbackClientIntf";
	
  public boolean IsGoodObject(Object Obj1, Object Obj2) throws RemoteException;
  public boolean IsRightValue(long val1, long val2) 
            throws RemoteException, Exception;

} // end CallbackClientIntf

The RMI Client

The RMI Remote Interface

Listing 4-3 Callback.java - A RMI Remote Server Interface

/* Copyright (c) 1999 BEA Systems, Inc.   All Rights Reserved */

import java.rmi.*;

/**
 *  Callback interface contains following methods 
 *  register(callBack): send clientcallback obj to server
 *  sendObject(Obj): send an object to server
 *  sendLong(Val): send a long value to server
 */
public interface Callback extends Remote 
{   
  public static final String NAME = "Callback";
  public static final int FAILURE = -1;
  public static final int SUCCESS = 0;
	
  public int register(Object callbackObj) throws RemoteException;
  public String sendObject(Object Obj)throws RemoteException;
  public String sendLong(long val) throws RemoteException, Exception;

} // end Callback

The Remote Object (RMI Server)

/* Copyright (c) 1999 BEA Systems, Inc.   All Rights Reserved */

import java.util.Hashtable;
import java.rmi.*;
import java.rmi.server.*;
import javax.naming.*; 

/**
 * Implements the methods defined in the Callback remote interface.
 */
public class CallbackImpl implements Callback
{
    private Object callbackObj;  // Object on client to verify parameters.
  
  // remember clientobject sent to server
    public int register(Object callbackObj) // throws RemoteException
  {
    if (callbackObj == null) return Callback.FAILURE;
    this.callbackObj = callbackObj;
    return Callback.SUCCESS;
  }

  // send regular dataobject to server
  // This method returns empty string on success or else error message.
  public String sendObject(Object Obj) throws RemoteException
  {
     // client call_back
     Object tmpObj = new DataObject("dataobj");
     if (!(callbackObj instanceof CallbackClientIntf)) 
       return "ClientObject is not instance of CallbackClientIntf at server side";
     
     // client call_back object
     if (((CallbackClientIntf)callbackObj).IsGoodObject(Obj, tmpObj))
        return "";
     else
        return "fail on send dataobject to server";
  }
  
  // send native type long to server
  // This method returns empty string on success or else error message.
  public String sendLong(long val) throws RemoteException, Exception
  {
     // client call_back
     if (!(callbackObj instanceof CallbackClientIntf)) 
       return "ClientObject is not instance of CallbackClientIntf at server side";

     // client call_back object
     if (((CallbackClientIntf)callbackObj).IsRightValue(val, 12345))
        return ""; 
     else
        return "fail on send long value to server";
  }
	
 /**
  * The main() method creates an instance of CallbackImpl class
  * and invokes the rebind() method of JNDI to register the
  * new objects.  It registers the objects with the name Callback
  * and also inform you that it has successfully completed
  * the registration process.
  */
  public static void main(String args[])
  {
      try{            
          Hashtable env = new Hashtable();
          env.put(Context.PROVIDER_URL,"");
          env.put(Context.INITIAL_CONTEXT_FACTORY,
           "com.beasys.jndi.WLEInitialContextFactory");
          Context ctx = new InitialContext(env);            
          ctx.rebind(Callback.NAME, new CallbackImpl());
                        
          System.out.println("CallbackImpl created and bound in JNDI to name "
			     + Callback.NAME);
      }
      catch (Exception e)
      {
          System.out.println("caught exception:"+e);
      }
  }//end main()        
} // end CallbackImpl

Running the RMI Callback Example

Extra Files Needed to Run the Callback Example

# Copyright (c) 2000 BEA Systems, Inc.   All Rights Reserved


*RESOURCES
IPCKEY        80952
MASTER        SITE1
MODEL         SHM
LDBAL         Y


*MACHINES
SAMS LMID=SITE1  #CHANGEME
            TUXDIR="d:\wledir"  #CHANGEME
            APPDIR="d:\work\rmi_callback" #CHANGEME
            TUXCONFIG="d:\work\rmi_callback\tuxconfig" #CHANGEME
            MAXWSCLIENTS=5

*GROUPS
DEFAULT:	LMID=SITE1
STDGRP      GRPNO=1 OPENINFO=NONE

*SERVERS
DEFAULT:    RESTART=Y MAXGEN=5 REPLYQ=Y CLOPT="-A"
TMSYSEVT    SRVGRP=STDGRP SRVID=1 RESTART=Y
TMFFNAME    SRVGRP=STDGRP  SRVID=2
            CLOPT="-A -- -N -M"
TMFFNAME    SRVGRP=STDGRP  SRVID=3
            CLOPT="-A -- -N"
TMFFNAME    SRVGRP=STDGRP  SRVID=4
            CLOPT="-A -- -F"
ISL         SRVGRP=STDGRP   SRVID=5
            CLOPT="-A -- -O -n //SAMS:10000" #CHANGEME

JavaServer  SRVGRP=STDGRP SRVID=6
            CLOPT="-A -- -M 0 testserver.jar"


*SERVICES

*INTERFACES

Listing 4-6 DataObject.java

/* Copyright (c) 1999 BEA Systems, Inc.   All Rights Reserved */

/**
 * DataObject is to test WLE RMI client callback 
 */
public class DataObject implements java.io.Serializable
{
    private String s;
    
    DataObject(String s)
    {
        this.s = s;
    }
    public String toString()
    {
        return s;
    }
    public boolean equals(Object Obj)
    {
       return (((DataObject)Obj).s.equals(s));
    }
}

Listing 4-7 ServerImpl.java

/* Copyright (c) 1999 BEA Systems, Inc.   All Rights Reserved */

import com.beasys.rmi.Startup;
import java.io.*;
import java.util.Properties;

/*
 * The ServerImpl class provides code to initialize and stop the server
 * invocation. ServerImpl is specified in the buildjavaserver XML input
 * file as the name of the server object.
 */
public class ServerImpl extends com.beasys.Tobj.Server {

  public boolean initialize(String[] args) {
    Properties p = new Properties();
    try {
      p.load(getClass().getResourceAsStream("startup.properties"));
    } catch (IOException ioe) {
      ioe.printStackTrace();
      return false;
    }
    try {
      Startup.main(p);
      return true;
    } catch (Exception e) {
      return false;
    }
  }

  public void release() {}
}

Listing 4-8 startup.properties

# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # 

# SYSTEM STARTUP FILES - Client callback
# ------------------------------------------------
#
# Register a startup class by giving it a virtual name and
# supplying its full pathname.
# weblogic.system.startupClass.[virtual_name]=[full_pathname]
#
# Add arguments for the startup class
# weblogic.system.startupArgs.[virtual_name]=[space separated arguments]

weblogic.system.startupClass.Callback=CallbackImpl

Listing 4-9 TestServer.xml

<?xml version = "1.0" ?>

<!--	Copyright (c) 1999 BEA Systems, Inc.
-->
<!DOCTYPE M3-SERVER SYSTEM "m3.dtd">

<M3-SERVER    server-descriptor-name = "testserver.ser"
               server-implementation = "ServerImpl" >

        <ARCHIVE name = "testserver.jar">
        <CLASS name="Callback"/>
        <CLASS name="CallbackClientIntf"/>
        <CLASS name="DataObject"/>
        <CLASS name="Callback_WLStub"/>
        <CLASS name="Callback_WLSkel"/>
        <CLASS name="CallbackClientIntf_WLStub"/>
        <CLASS name="CallbackClientIntf_WLSkel"/>
        <CLASS name="CallbackImpl"/>
        <FILE name="startup.properties" prefix=""/>
        </ARCHIVE>

</M3-SERVER>

Listing 4-10 Cleanup.cmd

rm *.class
rm *.jar
rm *.ser
rm tuxconfig
rm stderr
rm stdout
rm tmsysevt.dat
rm -rf .adm