/*

  * Copyright 1999-2001,2004 The Apache Software Foundation.

  *

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  *

  *      http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.apache.commons.workflow.demo;

 import java.io.File;

 import org.apache.commons.digester.Digester;

 import org.apache.commons.workflow.Activity;

 import org.apache.commons.workflow.Context;

 import org.apache.commons.workflow.ContextEvent;

 import org.apache.commons.workflow.ContextListener;

 import org.apache.commons.workflow.base.BaseContext;

 import org.apache.commons.workflow.base.BaseRuleSet;

 import org.apache.commons.workflow.core.CoreRuleSet;

 import org.apache.commons.workflow.io.IoRuleSet;

 import org.apache.commons.workflow.web.WebRuleSet;

 /**

  * <p>Demonstration program to illustrate how the Workflow Management System

  * is utilized.  It accepts a command line argument to an XML file that

  * contains an <code>&lt;activity&gt;</code> to be parsed and then executed.

  * If no file is specified, a default XML document will be utilized.</p>

  *

  * <p><strong>WARNING</strong> - This program is for illustration only while

  * the workflow management system is being developed, and it will not be

  * part of the final package.  Indeed, much of its functionality (such as

  * the parsing of XML files describing activities) will need to be encapsulated

  * inside the system, in ways that support the per-namespace step definitions

  * as outlined in the original proposal.</p>

  *

  * <p><strong>WARNING</strong> - This code depends on the version of Digester

  * currently in SVN - the 1.0 released version will not work correctly with

  * namespace prefixes.</p>

  *

  * <p><strong>WARNING</strong> - The namespace URLs in the example XML document

  * are not official - they are simply used to satisfy the syntax requirements

  * of the XML parser.  Official namespace URIs <em>will</em> be required for a

  * formal release of this technology, because that is key to the extensibility

  * of Step implementations.</p>

  *

  * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $

  * @author Craig R. McClanahan

  */

 public class Main implements ContextListener {

     // ----------------------------------------------------------- Main Program

     /**

      * The main program for the demo.

      *

      * @param args Command line arguments

      */

     public static void main(String args[]) {

         // Make sure there is a filename argument

         if (args.length != 1) {

             System.out.println("Usage:  java org.apache.commons.workflow.demo.Main {XML-file}");

             System.exit(1);

         }

         // Construct and utilize a new instance of this class

         Main main = new Main();

         main.process(args[0]);

     }

     // ----------------------------------------------------- Instance Variables

     /**

      * The Activity constructed by our Digester.

      */

     protected Activity activity = null;

     /**

      * The Digester used to process input files.

      */

     protected Digester digester = null;

     // ------------------------------------------------------------ Constructor

     /**

      * Construct a new instance of this class to process input files.

      */

     public Main() {

         super();

         digester = createDigester();

     }

     // -------------------------------------------------------- Support Methods

     /**

      * <p>Create a Digester instance that knows how to parse activities using

      * the <code>core</code> and <code>io</code> built-in Steps.</p>

      *

      * <p><strong>WARNING</strong> - This will ultimately be abstracted into

      * a mechanism to register the set of rule definitions associated with

      * a namespace.</p>

      */

     protected Digester createDigester() {

         // Construct and configure a new Digester instance

         Digester digester = new Digester();

         //        digester.setDebug(999);

         digester.setNamespaceAware(true);

         digester.setValidating(false);

         digester.push(this);

         // Add rules to recognize the built-in steps that we know about

         BaseRuleSet brs = new BaseRuleSet();

         digester.addRuleSet(brs);

         digester.addRuleSet(new CoreRuleSet());

         digester.addRuleSet(new IoRuleSet());

         // Add a rule to register the Activity being created

         digester.setRuleNamespaceURI(brs.getNamespaceURI());

         digester.addSetNext("activity", "setActivity",

                             "org.apache.commons.workflow.Activity");

         // Return the completed instance

         return (digester);

     }

     /**

      * Save the Activity that our Digester has constructed.

      *

      * @param activity The newly constructed Activity

      */

     public void setActivity(Activity activity) {

         this.activity = activity;

     }

     /**

      * Process the specified file.

      *

      * @param pathname Pathname of the specified XML file containing

      *  an activity definition

      */

     public void process(String pathname) {

         // Parse the activity definition

         try {

             System.out.println("Main:  Parsing activity file " + pathname);

             digester.parse(new File(pathname));

         } catch (Throwable t) {

             t.printStackTrace(System.out);

             return;

         }

         // Create a context and execute this activity

         try {

             System.out.println("Main:  Executing parsed activity");

             Context context = new BaseContext();

             context.setActivity(activity);

             context.addContextListener(this);

             context.execute();

         } catch (Throwable t) {

             t.printStackTrace(System.out);

             return;

         }

     }

     // ------------------------------------------------ ContextListener Methods

     /**

      * Invoked immediately after execution of the related Activity has

      * been completed normally, been suspended, or been aborted by

      * the throwing of a StepException.  The Step included in this event

      * will be the last one to be executed.

      *

      * @param event The <code>ContextEvent</code> that has occurred

      */

     public void afterActivity(ContextEvent event) {

         System.out.println("CL: afterActivity()");

     }

     /**

      * Invoked immediately after the specified Step was executed.

      *

      * @param event The <code>ContextEvent</code> that has occurred

      */

     public void afterStep(ContextEvent event) {

         System.out.println("CL: afterStep(" + event.getStep().getId() + ")");

     }

     /**

      * Invoked immediately before execution of the related Activity has

      * started.  The Step included in this event will be the first one

      * to be executed.

      *

      * @param event The <code>ContextEvent</code> that has occurred

      */

     public void beforeActivity(ContextEvent event) {

         System.out.println("CL: beforeActivity()");

     }

     /**

      * Invoked immediately before the specified Step is executed.

      *

      * @param event The <code>ContextEvent</code> that has occurred

      */

     public void beforeStep(ContextEvent event) {

         System.out.println("CL: beforeStep(" + event.getStep().getId() + ")");

     }

 }