public interface ISOPackager extends LogSource {
     public byte[] pack (ISOComponent m) throws ISOException;
     public int unpack (ISOComponent m, byte[] b) throws ISOException;
     public void unpack (ISOComponent m, InputStream in) throws IOException, ISOException;
     public String getFieldDescription(ISOComponent m, int fldNumber);
     public ISOMsg createISOMsg ();
}

<!DOCTYPE isopackager SYSTEM "genericpackager.dtd">
<!-- ISO 8583:1993 (BINARY) field descriptions for GenericPackager -->
<isopackager>
  <isofield
      id="0"
      length="4"
      name="Message Type Indicator"
      pad="false"
      class="org.jpos.iso.IFB_NUMERIC"/>
  <isofield
      id="1"
      length="16"
      name="Bitmap"
      class="org.jpos.iso.IFB_BITMAP"/>
    ...
    ...
    ...
  <isofield
        id="128"
        length="8"
        name="Message authentication code field"
       class="org.jpos.iso.IFB_BINARY"/>
 </isopackager>

GenericPackager packager = new GenericPackager("miPaquetePersonalizado.xml");

//Para reempaquetar
iso.recalcBitMap();
//o usar los métodos para empaquetar
iso.pack();
//o
// Para desempaquetar
iso.unpack();

ISOMsg msgiso = new ISOMsg();
//Importante el encabezado 800,
String mti = "0800";
//Si tu  mensaje lleva header aqui se pone la cadena de texto
String header = "tuHeader";
msgiso.setMTI(mti);
 
//Agregamos el Header del mensaje si lo necesitamos, el header se tiene que guardar en bytes
BaseHeader db = new BaseHeader(header .getBytes());
msgiso.setHeader(db);
 
//Campo 7, con ISODate obtenemos la fecha en formato ISO8583
msgiso.set(new ISOField(7, ISODate.getDateTime(new Date())));
 
//Campo 11, con ISOUtil.zeropad, rellenamos de ceros
msgiso.set(new ISOField(11, ISOUtil.zeropad(new Integer("555555").toString(), 6)));
 
//Campo 70, el 301 por defecto
msgiso.set(new ISOField(70, "301"));
 
//Lo empaquetamos, generico o echo a la medida, tu eliges.
GenericPackager packager = new GenericPackager("miPaquetePersonalizado.xml");
 
//Empaquetamos el mensake
msgiso.setPackager(packager);
 
//Construimos el BitMap
msgiso.recalcBitMap();

/*
 * jPOS Project [http://jpos.org]
 * Copyright (C) 2000-2008 Alejandro P. Revilla
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
package org.jpos.util;
 
import java.util.Date;
import java.util.Locale;
import java.util.Iterator;
import java.io.IOException;
import java.text.SimpleDateFormat;
import org.jpos.core.Configurable;
import org.jpos.core.Configuration;
import org.jpos.core.ConfigurationException;
import org.jpos.q2.Q2;
import winterwell.jtwitter.*;
 
/**
 * Twitter Listener
 *
 *  requires jtwitter.jar from http://www.winterwell.com/software/jtwitter.php
 *
 *  Sample configuration:
 *
 *  <log-listener class="org.jpos.util.TwitterLogListener">
 *     <property name="twitterUsername" value="paymentsystems" />
 *     <property name="twitterPassword" value="SuperSecretPassword" />
 *     <property name="tags" value="twitter" />
 *     <property name="prefix" value="[jPOS]"/>
 *  </log-listener>
 *
 */
public class TwitterLogListener implements LogListener, Configurable {
    private Configuration   cfg;
    private String          twitterUsername;
    private String          twitterPassword;
    private String          prefix;
    private String          tags;
    private String          twitterMessage;
 
    private int             MAX_MESSAGE_SIZE = 140;
 
    public TwitterLogListener () {
        super();
    }
    public synchronized LogEvent log (LogEvent ev) {
        if (ev.tag != null && tags.indexOf(ev.tag) != -1) {
 
            Twitter twitter = new Twitter(twitterUsername,twitterPassword);
            StringBuilder sb = new StringBuilder();
            if (prefix != null) {
                sb.append (prefix);
                sb.append (' ');
            }
            Iterator iter = ev.payLoad.iterator();
            for (int i=0; iter.hasNext(); i++) {
                if (i>0)
                    sb.append (' ');
                    sb.append (iter.next().toString());
            }
            if (sb.toString().length()>MAX_MESSAGE_SIZE) {
                twitterMessage = sb.toString().substring(0,MAX_MESSAGE_SIZE);
            } else {
                twitterMessage = sb.toString();
            }
 
            try {
                twitter.updateStatus(twitterMessage);
            } catch (TwitterException e) {
                ev.addMessage ("--- TwitterLogListener error ---");
                ev.addMessage (e);
            }
        }
        return ev;
    }
    public void setConfiguration (Configuration cfg)
        throws ConfigurationException
    {
        this.cfg = cfg;
        try {
            twitterUsername = cfg.get ("twitterUsername");
            twitterPassword = cfg.get ("twitterPassword");
            tags     = cfg.get ("tags", "twitter");
            prefix = cfg.get ("prefix", null);
        } catch (Exception e) {
            throw new ConfigurationException (e);
        }
    }
}

<server name="xml-server" class="org.jpos.q2.iso.QServer" logger="Q2">
<attr name="port" type="java.lang.Integer">8000</attr>
<channel name="dummyclient.channel" class="org.jpos.iso.channel.BASE24Channel"
packager="org.jpos.iso.packager.GenericPackager" logger="Q2">
<property name="packager-config" value="cfg/packager/base24.xml" />
</channel>
<!-- Solo agregamos esta línea a la configuración de nuestro Q2 Server -->
<request-listener class="mipaquete.MiListenerPersonalizado" logger="Q2">
</server>

import org.jpos.iso.ISODate;
import org.jpos.iso.ISOException;
import org.jpos.iso.ISOField;
import org.jpos.iso.ISOMsg;
import org.jpos.iso.ISORequestListener;
import org.jpos.iso.ISOSource;
import org.jpos.iso.ISOUtil;
import org.jpos.iso.header.BaseHeader;
import org.jpos.q2.iso.QMUX;
import org.jpos.util.Log;
import org.jpos.util.NameRegistrar;
/**
* http://blog.jotadeveloper.com
*Creado por JotaDeveloper
*/
public class MiListenerPersonalizado extends Log implements ISORequestListener {
 
	@Override
	public boolean process(ISOSource source, ISOMsg m) {
		ISOMsg responseISOMsg = null;
		QMUX mux = null;
		try {
                        //Buscamos en el jPOS Space nuestro multiplextor, siempre se busca con el prefijo mux seguido por un punto
			mux = (QMUX) NameRegistrar.get("mux.mymux");
			mux.setLogger("mux");
                        //Se recupera la respuesta
			responseISOMsg = mux.request(m, 20000);
		} catch (NameRegistrar.NotFoundException ex) {
 
		} catch (ISOException ex) {
 
		}
		//Es importante siempre regresar true.
		return true;
	}
}

<mux class="org.jpos.q2.iso.QMUX" logger="Q2" name="mymux">
<in>sample-receive</in>
<out>sample-send</out>
<!-- Este key, es la llave por la cual identificaras unicamente cada mensaje, es importante
poner el valor indicado, generalmente es el 11 o el 17 -->
<key>55</key>
</mux>