Package org.apache.cocoon.components.pipeline

Source Code of org.apache.cocoon.components.pipeline.AbstractEventPipeline

/*

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

Copyright (C) 1999-2002 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.components.pipeline;

import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.component.Component;
import org.apache.avalon.framework.component.ComponentException;
import org.apache.avalon.framework.component.ComponentManager;
import org.apache.avalon.framework.component.ComponentSelector;
import org.apache.avalon.framework.parameters.Parameters;
import org.apache.cocoon.ProcessingException;
import org.apache.cocoon.components.saxconnector.SAXConnector;
import org.apache.cocoon.environment.Environment;
import org.apache.cocoon.generation.Generator;
import org.apache.cocoon.transformation.Transformer;
import org.apache.cocoon.xml.AbstractXMLProducer;
import org.apache.cocoon.xml.XMLConsumer;
import org.apache.cocoon.xml.XMLProducer;
import org.xml.sax.SAXException;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;

/**
* @author <a href="mailto:Giacomo.Pati@pwr.ch">Giacomo Pati</a>
* @author <a href="mailto:cziegeler@Carsten Ziegeler">Carsten Ziegeler</a>
* @author <a href="mailto:sylvain@apache.org">Sylvain Wallez</a
* @author <a href="mailto:barozzi@nicolaken.com">Nicola Ken Barozzi</a>
* @author <a href="mailto:proyal@managingpartners.com">Peter Royal</a>
* @version CVS $Id: AbstractEventPipeline.java,v 1.9 2002/04/06 17:57:54 vgritsenko Exp $
*/
public abstract class AbstractEventPipeline
  extends AbstractXMLProducer
  implements EventPipeline, Disposable {

    // Generator stuff
    protected Generator generator;
    protected Parameters generatorParam;
    protected String generatorSource;
    protected ComponentSelector generatorSelector;

    // Transformer stuff
    protected ArrayList transformers = new ArrayList();
    protected ArrayList transformerParams = new ArrayList();
    protected ArrayList transformerSources = new ArrayList();
    protected ArrayList transformerSelectors = new ArrayList();

    protected ArrayList connectors = new ArrayList();

    /** the component manager set with compose() */
    protected ComponentManager manager;

    /** is a SAXConnector configured? */
    protected boolean configuredSAXConnector;

    /** the component manager set with compose() and recompose() */
    protected ComponentManager newManager;

    public void compose (ComponentManager manager)
    throws ComponentException {
        this.manager = manager;
        // cache this test for a little bit performance
        this.configuredSAXConnector = this.manager.hasComponent(SAXConnector.ROLE);
        this.newManager = manager;
    }

    public void recompose (ComponentManager manager)
    throws ComponentException {
        this.newManager = manager;
    }

    /**
     * @deprecated The NotifyingGenerator gets the Notificable from the objectModel
     */
    public void setGenerator (String role, String source, Parameters param, Exception e)
    throws Exception {
        this.setGenerator (role, source, param);
        if (this.generator instanceof org.apache.cocoon.sitemap.ErrorNotifier) {
            ((org.apache.cocoon.sitemap.ErrorNotifier)this.generator).setThrowable(e);
        }
    }

    public void setGenerator (String role, String source, Parameters param)
    throws Exception {
        if (this.generator != null) {
            throw new ProcessingException ("Generator already set. You can only select one Generator (" + role + ")");
        }
        this.generatorSelector = (ComponentSelector) this.newManager.lookup(Generator.ROLE + "Selector");
        this.generator = (Generator) this.generatorSelector.select(role);
        this.generatorSource = source;
        this.generatorParam = param;
    }

    public Generator getGenerator() {
        return this.generator;
    }

    public void addTransformer (String role, String source, Parameters param)
    throws Exception {
        ComponentSelector selector = (ComponentSelector) this.newManager.lookup(Transformer.ROLE + "Selector");
        this.transformerSelectors.add(selector);
        this.transformers.add((Transformer)selector.select(role));
        this.transformerSources.add(source);
        this.transformerParams.add(param);
    }

    public boolean process(Environment environment) throws Exception {
        if (!checkPipeline()) {
            throw new ProcessingException("Attempted to process incomplete pipeline.");
        }

        setupPipeline(environment);
        connectPipeline(environment);

        // execute the pipeline:
        try {
            this.generator.generate();
        } catch ( Exception e ) {
            throw e;
        }
        return true;
    }

    /** Sanity check the non-reader pipeline.
     * @return true if the pipeline is 'sane', false otherwise.
     */
    protected boolean checkPipeline() {
        if ( this.generator == null ) {
            return false;
        }

        Iterator itt = this.transformers.iterator();
        while ( itt.hasNext() ) {
            if ( itt.next() == null) {
                return false;
            }
        }

        if (super.xmlConsumer == null &&
            super.contentHandler == null &&
            super.lexicalHandler == null) {
            return false;
        }
        return true;
    }

    /** Setup pipeline components.
     */
    protected void setupPipeline(Environment environment)
    throws ProcessingException {
        try {
            // setup the generator
            this.generator.setup(
                environment,
                environment.getObjectModel(),
                generatorSource,
                generatorParam
            );

            Iterator transformerItt = this.transformers.iterator();
            Iterator transformerSourceItt = this.transformerSources.iterator();
            Iterator transformerParamItt = this.transformerParams.iterator();

            while ( transformerItt.hasNext() ) {
                Transformer trans = (Transformer)transformerItt.next();
                trans.setup(
                    environment,
                    environment.getObjectModel(),
                    (String)transformerSourceItt.next(),
                    (Parameters)transformerParamItt.next()
                );
            }
        } catch (SAXException e) {
            throw new ProcessingException(
                "Could not setup pipeline.",
                e
            );
        } catch (IOException e) {
            throw new ProcessingException(
                "Could not setup pipeline.",
                e
            );
        }
    }

    /** Connect the pipeline.
     */
    protected void connectPipeline(Environment environment) throws ProcessingException {
        XMLProducer prev = (XMLProducer)this.generator;
        XMLConsumer next;

        try {
            Iterator itt = this.transformers.iterator();
            while ( itt.hasNext() ) {
                if (this.configuredSAXConnector) {
                    // connect SAXConnector
                    SAXConnector connect = (SAXConnector) this.manager.lookup(SAXConnector.ROLE);
                    connect.setup(environment,environment.getObjectModel(), null, null);
                    this.connectors.add(connect);
                    next = connect;
                    prev.setConsumer(next);
                    prev = connect;
                }
                // Connect next component.
                Transformer trans = (Transformer) itt.next();
                next = trans;
                prev.setConsumer(next);
                prev = trans;
            }

            if (this.configuredSAXConnector) {
                // insert SAXConnector
                SAXConnector connect = (SAXConnector) this.manager.lookup(SAXConnector.ROLE);
                connect.setup(environment,environment.getObjectModel(), null, null);
                this.connectors.add(connect);
                next = connect;
                prev.setConsumer(next);
                prev = connect;
            }
            // insert this consumer
            prev.setConsumer(super.xmlConsumer);
        } catch ( IOException e ) {
            throw new ProcessingException(
                "Could not connect pipeline.",
                e
            );
        } catch ( SAXException e ) {
            throw new ProcessingException(
                "Could not connect pipeline.",
                e
            );
        } catch ( ComponentException e ) {
            throw new ProcessingException(
                "Could not connect pipeline.",
                e
            );
        }

    }

    public void recycle() {
        super.recycle();

        try {
            // Release generator.
            if (generatorSelector != null) {
                generatorSelector.release(this.generator);
            }

            // Release transformers
            int size = this.transformerSelectors.size();
            for (int i = 0; i < size; i++)
            {
                ((ComponentSelector)this.transformerSelectors.get(i)).release(
                    (Component)this.transformers.get(i)
                );
            }

            // Release connectors
            Iterator itc = this.connectors.iterator();
            while ( itc.hasNext() ) {
                this.manager.release((Component) itc.next());
            }
        } catch ( Exception e ) {
            getLogger().warn(
                "Failed to release components from event pipeline.",
                e
            );
        } finally {
            // FIXME : in theory selectors should be released on their respective managers
            // but this causes no harm since they're ThreadSafe
            this.generatorSelector = null;
            this.generator = null;
            this.generatorParam = null;
            this.transformerSelectors.clear();
            this.transformers.clear();
            this.transformerParams.clear();
            this.transformerSources.clear();
            this.connectors.clear();
        }
    }

    public void dispose() {
        // Nothing here
    }
}
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