Package org.apache.cocoon.components.flow

Source Code of org.apache.cocoon.components.flow.AbstractInterpreter

/*

============================================================================
                   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,
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OF USE, DATA, OR  PROFITS; OR BUSINESS  INTERRUPTION)  HOWEVER CAUSED AND ON
ANY  THEORY OF LIABILITY,  WHETHER  IN CONTRACT,  STRICT LIABILITY,  OR TORT
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THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/
package org.apache.cocoon.components.flow;

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.Composable;
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.context.ContextException;
import org.apache.avalon.framework.context.Contextualizable;
import org.apache.avalon.framework.logger.AbstractLogEnabled;
import org.apache.avalon.framework.thread.SingleThreaded;
import org.apache.cocoon.Constants;
import org.apache.cocoon.Processor;
import org.apache.cocoon.components.CocoonComponentManager;
import org.apache.cocoon.components.treeprocessor.sitemap.PipelinesNode;
import org.apache.cocoon.environment.Context;
import org.apache.cocoon.environment.Environment;
import org.apache.cocoon.environment.wrapper.EnvironmentWrapper;

import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Map;

/**
* Abstract superclass for various scripting languages used by Cocoon
* for flow control. Defines some useful behavior like the ability to
* reload script files if they get modified (useful when doing
* development), and passing the control to Cocoon's sitemap for
* result page generation.
*
* @author <a href="mailto:ovidiu@cup.hp.com">Ovidiu Predescu</a>
* @since March 15, 2002
* @version CVS $Id: AbstractInterpreter.java,v 1.4 2003/05/18 16:36:40 vgritsenko Exp $
*/
public abstract class AbstractInterpreter extends AbstractLogEnabled
  implements Component, Composable, Contextualizable, Interpreter,
             SingleThreaded, Configurable
{
    /**
     * List of source locations that need to be resolved.
     */
    protected ArrayList needResolve = new ArrayList();

    protected org.apache.cocoon.environment.Context context;
    protected ComponentManager manager;
    protected ContinuationsManager continuationsMgr;

    /**
     * Whether reloading of scripts should be done. Specified through
     * the "reload-scripts" attribute in <code>flow.xmap</code>.
     */
    protected boolean reloadScripts;

    /**
     * Interval between two checks for modified script files. Specified
     * through the "check-time" XML attribute in <code>flow.xmap</code>.
     */
    protected long checkTime;

    public void configure(Configuration config) throws ConfigurationException {
        reloadScripts = config.getChild("reload-scripts").getValueAsBoolean(false);
        checkTime = config.getChild("check-time").getValueAsLong(1000L);
    }

    public void compose(ComponentManager manager) throws ComponentException {
        this.manager = manager;

        // FIXME: Why is the manager null here?
        if (manager != null) {
            continuationsMgr
                    = (ContinuationsManager)manager.lookup(ContinuationsManager.ROLE);
        }
    }

    public void contextualize(org.apache.avalon.framework.context.Context context)
            throws ContextException
    {
        this.context = (Context)context.get(Constants.CONTEXT_ENVIRONMENT_CONTEXT);
    }

    /**
     * Registers a source file with the interpreter. Using this method
     * an implementation keeps track of all the script files which are
     * compiled. This allows them to reload the script files which get
     * modified on the file system.
     *
     * <p>The parsing/compilation of a script file by an interpreter
     * happens in two phases. In the first phase the file's location is
     * registered in the <code>needResolve</code> array.
     *
     * <p>The second is possible only when a Cocoon
     * <code>Environment</code> is passed to the Interpreter. This
     * allows the file location to be resolved using Cocoon's
     * <code>SourceFactory</code> class.
     *
     * <p>Once a file's location can be resolved, it is removed from the
     * <code>needResolve</code> array and placed in the
     * <code>scripts</code> hash table. The key in this hash table is
     * the file location string, and the value is a
     * DelayedRefreshSourceWrapper instance which keeps track of when
     * the file needs to re-read.
     *
     * @param source the location of the script
     *
     * @see org.apache.cocoon.components.source.SourceFactory
     * @see org.apache.cocoon.environment.Environment
     * @see org.apache.cocoon.components.source.impl.DelayedRefreshSourceWrapper
     */
    public void register(String source)
    {
        synchronized(this) {
            needResolve.add(source);
        }
    }

    /**
     * Call the Cocoon sitemap for the given URI, sending the output of the
     * eventually matched pipeline to the specified outputstream.
     *
     * @param uri The URI for which the request should be generated.
     * @param biz Extra data associated with the subrequest.
     * @param out An OutputStream where the output should be written to.
     * @param env The environment of the original request.
     * @return Whatever the Cocoon processor returns (????).
     * @exception Exception If an error occurs.
     */
    public boolean process(String uri, Object biz, OutputStream out, Environment env)
            throws Exception {
        if (out == null) {
            throw new NullPointerException("No outputstream specified for process");
        }

        // Create a wrapper environment for the subrequest to be processed.
        EnvironmentWrapper wrapper = new EnvironmentWrapper(env, uri, "", getLogger());
        wrapper.setURI("",uri);
        wrapper.setOutputStream(out);
        wrapper.setAttribute("bean-dict", biz);

        // Attermpt to start processing the wrapper environment
        Object key = CocoonComponentManager.startProcessing(wrapper);

        Processor processor = null;
        boolean result = false;
        try {
            // Retrieve a processor instance
            processor = (Processor)this.manager.lookup(Processor.ROLE);

            // Enter the environment
            CocoonComponentManager.enterEnvironment(wrapper, this.manager, processor);

            // Process the subrequest
            result = processor.process(wrapper);
            wrapper.commitResponse();
            out.flush();

            // Return whatever the processor returned us
            return(result);
        } catch (Exception any) {
            throw(any);
        } finally {
            // Leave the environment, terminate processing and release processor
            CocoonComponentManager.leaveEnvironment();
            CocoonComponentManager.endProcessing(wrapper, key);
            this.manager.release(processor);
        }
    }

    public void forwardTo(String uri, Object bizData,
                          WebContinuation continuation,
                          Environment environment)
            throws Exception
    {
        Map objectModel = environment.getObjectModel();
        FlowHelper.setContextObject(objectModel, bizData);
        FlowHelper.setWebContinuation(objectModel, continuation);
        PipelinesNode.getRedirector(environment).redirect(false, uri);
    }
}
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