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From "Christoph Gaffga" <cgaf...@triplemind.com>
Subject Re: EJB + Cocoon, "Best Practices" / Betwixt
Date Tue, 09 Sep 2003 22:29:02 GMT
> that invokes the EJB and returns the DTO. It then passes the DTO to
Betwixt
> which converts it to SAX events.  I posted the BeanGenerator on the list a

Perheaps you are also interested in a BetwixtTransformer, analoge to
CastorTransformer?
I post it here, perheaps anyone can put it in the scratchpad?

regards
Christoph


org.apache.cocoon.tranformation.BetwixtTransformer:
---------------------------------------------------

/*

============================================================================
                   The Apache Software License, Version 1.1

============================================================================
 Copyright (C) 1999-2003 The Apache Software Foundation. All rights
reserved.
 Redistribution and use in source and binary forms, with or without
modifica-
 tion, are permitted provided that the following conditions are met:
 1. Redistributions of  source code must  retain the above copyright
notice,
    this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
notice,
    this list of conditions and the following disclaimer in the
documentation
    and/or other materials provided with the distribution.
 3. The end-user documentation included with the redistribution, if any,
must
    include  the following  acknowledgment:  "This product includes
software
    developed  by the  Apache Software Foundation
(http://www.apache.org/)."
    Alternately, this  acknowledgment may  appear in the software itself,
if
    and wherever such third-party acknowledgments normally appear.
 4. The names "Apache Cocoon" and  "Apache Software Foundation" must  not
be
    used to  endorse or promote  products derived from  this software
without
    prior written permission. For written permission, please contact
    apache@apache.org.
 5. Products  derived from this software may not  be called "Apache", nor
may
    "Apache" appear  in their name,  without prior written permission  of
the
    Apache Software Foundation.
 THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
AND
 FITNESS  FOR A PARTICULAR  PURPOSE ARE  DISCLAIMED.  IN NO  EVENT SHALL
THE
 APACHE SOFTWARE  FOUNDATION  OR ITS CONTRIBUTORS  BE LIABLE FOR  ANY
DIRECT,
 INDIRECT, INCIDENTAL, SPECIAL,  EXEMPLARY, OR CONSEQUENTIAL  DAMAGES
(INCLU-
 DING, BUT NOT LIMITED TO, PROCUREMENT  OF SUBSTITUTE GOODS OR SERVICES;
LOSS
 OF USE, DATA, OR  PROFITS; OR BUSINESS  INTERRUPTION)  HOWEVER CAUSED AND
ON
 ANY  THEORY OF LIABILITY,  WHETHER  IN CONTRACT,  STRICT LIABILITY,  OR
TORT
 (INCLUDING  NEGLIGENCE OR  OTHERWISE) ARISING IN  ANY WAY OUT OF THE  USE
OF
 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 This software  consists of voluntary contributions made  by many
individuals
 on  behalf of the Apache Software  Foundation and was  originally created
by
 Stefano Mazzocchi  <stefano@apache.org>. For more  information on the
Apache
 Software Foundation, please see <http://www.apache.org/>.
 */

package org.apache.cocoon.transformation;

import java.lang.reflect.Proxy;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;

import org.apache.avalon.framework.configuration.Configurable;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.cocoon.environment.Context;
import org.apache.cocoon.environment.ObjectModelHelper;
import org.apache.cocoon.environment.Request;
import org.apache.cocoon.environment.Session;
import org.apache.cocoon.environment.SourceResolver;
import org.apache.commons.betwixt.XMLIntrospector;
import org.apache.commons.betwixt.io.SAXBeanWriter;
import org.apache.commons.betwixt.strategy.ClassNormalizer;
import org.apache.commons.logging.impl.LogKitLogger;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;

/**
 * Betwixt transformer marshals a object from the Sitemap, Session, Request
or
 * the Conext into a series of SAX events.
 *
 * Configuation: The betwixt transformer can be configured to not output
element
 * reference ids. The default setting is to output reference IDs.
 * <pre>
 *   &lt;map:transformer name="betwixt"
src="org.apache.cocoon.transformation.BetwixtTransformer"
 *     &lt;ref-ids&gt;true&lt;/ref-ids&gt;
 *   &lt;/map:transformer&gt;
 * </pre>
 *
 * A sample for the use:
 * <pre>
 *   &lt;root
xmlns:betwixt="http://apache.org/cocoon/betwixt-transfomer"&gt;
 *    &lt;betwixt:include name="invoice" /&gt;
 *    &lt;betwixt:include name="product" scope="sitemap" /&gt;
 *    &lt;betwixt:include name="product2" element="other-product" /&gt;
 *   &lt;/root&gt;
 * </pre>
 * The <code>BetwixtTransfomer</code> support only one Element
<code>betwixt:include</code>.
 * This element is replaced with the marshalled object. The Object given
through the
 * attribute <code>name</code> will be searched in the <code>request</code>,
<code>session</code>,
 * <code>context</code> and at least in <code>sitemap</code>.
 * If the scope is explicitly given, the object will ge located only there.
 * The attribute <code>element</code> can be given to specify an alternativ
 * root element for the object. Collections are marshalled by marshalling
 * each object it contains.
 *
 * @see <a href="http://jakarta.apache.org/commons/betwixt/">Betwixt Projekt
Homepage</a>
 * @author <a href="mailto:cgaffga@triplemind.com">Christoph Gaffga</a>
 */
public class BetwixtTransformer extends AbstractTransformer implements
Configurable {
  private static final String BETWIXT_NSURI =
"http://apache.org/cocoon/betwixt-transfomer";

  private final static String CMD_INCLUDE = "include";
  private final static String ATTR_NAME = "name";
  private final static String ATTR_SCOPE = "scope";
  private final static String SCOPE_SITEMAP = "sitemap";
  private final static String SCOPE_SESSION = "session";
  private final static String SCOPE_REQUEST = "request";
  private final static String SCOPE_CONTEXT = "context";
  private final static String ATTR_ELEMENT = "element";
  private final static String CONF_REFIDS = "ref-ids";

  // Introspector to share XMLBeanInfo cache
  private static XMLIntrospector introspector;

  private boolean refIds = true;

  private Map objectModel = null;
  private boolean inBetwixtElement = false;
  private SAXBeanWriter beanWriter = null;

  public void configure(Configuration conf) throws ConfigurationException {
    final String refIds = conf.getChild(CONF_REFIDS).getValue("true");
    this.refIds = "false".equals(refIds) || "no".equals(refIds);
  }

  public void setup(SourceResolver resolver, Map objectModel, String src,
Parameters par) {
    this.objectModel = objectModel;
  }

  public void recycle() {
    this.objectModel = null;
    this.inBetwixtElement = false;
  }

  public void endElement(String uri, String name, String raw) throws
SAXException {
    if (BETWIXT_NSURI.equals(uri)) {
      this.inBetwixtElement = false;
    } else {
      super.endElement(uri, name, raw);
    }
  }

  public void startElement(String uri, String name, String raw, Attributes
attr) throws
      SAXException {
    if (BETWIXT_NSURI.equals(uri)) {
      this.inBetwixtElement = true;
      process(name, attr);
    } else {
      super.startElement(uri, name, raw, attr);
    }
  }

  public void characters(char[] ch, int start, int len) throws SAXException
{
    if (!this.inBetwixtElement) {
      super.characters(ch, start, len);
    }
  }

  private void process(String command, Attributes attr) throws SAXException
{
    if (CMD_INCLUDE.equals(command)) {
      final String scope = attr.getValue(ATTR_SCOPE);
      final String name = attr.getValue(ATTR_NAME);
      if (name == null) {
        throw new SAXException("Required attribute name is missing on
element " + CMD_INCLUDE);
      }

      final String element = attr.getValue(ATTR_ELEMENT);
      if (element == null) {
        throw new SAXException("Attribute " + ATTR_ELEMENT + " can not be
empty");
      }

      Object bean = null;
      if (scope == null || SCOPE_REQUEST.equals(scope)) {
        final Request request = ObjectModelHelper.getRequest(objectModel);
        bean = request.getAttribute(name);
      }
      if ( (scope == null && bean == null) || SCOPE_SESSION.equals(scope)) {
        final Session session =
ObjectModelHelper.getRequest(objectModel).getSession(false);
        if (session != null) {
          bean = session.getAttribute(name);
        }
      }
      if ( (scope == null && bean == null) || SCOPE_CONTEXT.equals(scope)) {
        final Context context = ObjectModelHelper.getContext(objectModel);
        if (context != null) {
          bean = context.getAttribute(name);
        }
      }
      if ( (scope == null && bean == null) || SCOPE_SITEMAP.equals(scope)) {
        bean = objectModel.get(name);
      }

      if (bean != null) {
        includeBean(name, bean, element);
      } else {
        getLogger().warn("Bean " + name + " could not be found");
      }
    } else {
      throw new SAXException("Unknown command: " + command);
    }
  }

  private void includeBean(String name, Object bean, String element) {
    try {
      if (this.beanWriter == null) {
        this.beanWriter = new SAXBeanWriter(this.contentHandler);
        synchronized (this.introspector) {
          if (this.introspector == null) {
            this.introspector = this.beanWriter.getXMLIntrospector();
            this.introspector.setLog(new LogKitLogger("betwixt"));
            /* The following is needed for EJB */
            this.introspector.setClassNormalizer(new ClassNormalizer() {
              public Class normalize(Class clazz) {
                if (Proxy.isProxyClass(clazz) &&
clazz.getInterfaces().length > 0) {
                  return clazz.getInterfaces()[0];
                }
                return super.normalize(clazz);
              }
            });

          } else {
            this.beanWriter.setXMLIntrospector(this.introspector);
          }
        }
        beanWriter.getBindingConfiguration().setMapIDs(this.refIds);
      }

      if (bean instanceof Collection) {
        Iterator i = ( (Collection) bean).iterator();
        while (i.hasNext()) {
          if (element == null) {
            beanWriter.write(bean);
          } else {
            beanWriter.write(element, bean);
          }
        }
      } else {
        if (element == null) {
          beanWriter.write(bean);
        } else {
          beanWriter.write(element, bean);
        }
      }
    } catch (Exception e) {
      getLogger().warn("Failed to marshal bean " + name, e);
    }
  }

}



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