defineexpression.java

这是一个关于工作流管理的系统

/*
 * Copyright (c) 2005, John Mettraux, OpenWFE.org
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 * . Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.  
 * 
 * . 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.
 * 
 * . Neither the name of the "OpenWFE" nor the names of its contributors may be
 *   used to endorse or promote products derived from this software without
 *   specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS 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 COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, 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.
 *
 * $Id: DefineExpression.java,v 1.21 2005/05/17 16:40:23 jmettraux Exp $
 */

//
// DefineExpression.java
//
// [e-mail]
//
// generated with 
// jtmpl 1.1.01 2004/05/19 ([e-mail])
//

package openwfe.org.engine.expressions;

import openwfe.org.ApplicationContext;
import openwfe.org.engine.Definitions;
import openwfe.org.engine.expool.ExpressionPool;
import openwfe.org.engine.history.History;
import openwfe.org.engine.workitem.InFlowWorkItem;
import openwfe.org.engine.expressions.map.ExpressionMap;
import openwfe.org.engine.expressions.raw.RawExpression;


/**
 * This expression may interpret 'workflow-definition', 'subprocess-definition'
 * and above all 'define'
 *
 * <p><font size=2>CVS Info :
 * <br>$Author: jmettraux $
 * <br>$Id: DefineExpression.java,v 1.21 2005/05/17 16:40:23 jmettraux Exp $ </font>
 *
 * @author [e-mail]
 */
public class DefineExpression

    extends AbstractCompositeFlowExpression

    implements DefinitionExpression

{

    private final static org.apache.log4j.Logger log = org.apache.log4j.Logger
        .getLogger(DefineExpression.class.getName());

    //
    // CONSTANTS & co

    //
    // FIELDS

    //
    // CONSTRUCTORS

    //
    // METHODS

    //
    // BEAN METHODS

    //
    // METHODS from DefinitionExpression

    /**
     * This expression's implementation of eval() will yield a 
     * FlowExpressionId pointing to the body of the definition
     */
    public Object eval (final InFlowWorkItem wi)
        throws ApplyException
    {
        //
        // interpret all the definitions
        
        final java.util.Map vars = new java.util.HashMap();

        RawExpression body = null;
        
        final java.util.Iterator it = getChildren().iterator();
        while (it.hasNext())
        {
            final FlowExpressionId fei = 
                (FlowExpressionId)it.next();
            final RawExpression exp = 
                (RawExpression)getExpressionPool().fetch(fei);

            log.debug("eval() child is "+fei);

            if ( ! exp.isDefinition())
            {
                if (body == null)
                {
                    body = exp;
                    body.getVariables().putAll(vars);
                }

                continue;
            }

            //
            // then it's a definition

            try
            {
                define(vars, body, exp, wi);
            }
            catch (final BuildException be)
            {
                throw new ApplyException
                    ("Failed to bind definition", be);
            }
        }

        //
        // then apply the root (the body of the definition)
        
        if (body == null)
            throw new ApplyException("No body for definition "+getId());

        final FlowExpressionId id = body.getId();

        log.debug("eval() body is "+id);

        return id;
    }

    private void define 
        (final java.util.Map vars, 
         final RawExpression body,
         final RawExpression re, 
         final InFlowWorkItem wi)
    throws 
        BuildException, ApplyException
    {
        //
        // determine name
        
        final String name = re.getDefinitionName();

        //
        // postulate : re points to a DefinitionExpression

        final DefinitionExpression de = 
            (DefinitionExpression)re.resolveExpression(wi);

        //
        // get parent and set variable at its level
        
        final Object value = de.eval(wi);
        
        if (value != null)
        {
            if (body != null)
                body.setLocalVariable(name, value);
            else
                vars.put(name, value);
        }

        //this.storeItself();
        // not nessary anymore...
    }

    //
    // METHODS from FlowExpression

    /**
     * Interprets all definitions, THEN applies the body...
     */
    public void apply (final InFlowWorkItem wi) 
        throws ApplyException
    {
        final FlowExpressionId fei = (FlowExpressionId)this.eval(wi);

        this.setChildren(new java.util.ArrayList(1));
        this.getChildren().add(fei);

        //
        // history logging
        
        String message = "launching";
        if (getParent() != null) message = "launching sub";

        historyLog(wi, History.EVT_FLOW_START, null, message);

        //
        // history item

        wi.addHistoryItem(getId(), this.getClass().getName(), message);

        //
        // launching

        getExpressionPool().apply(fei, wi);
    }

    /**
     * When the workflow is instantied, all expressions from root expression to
     * all leaf expressions see their 'apply' method get called.
     * When then leaf expressions (ParticipantExpressions) get answers from
     * their participant, they communicate the modified workitem to their
     * father expression with its 'reply' method.
     */
    public void reply (final InFlowWorkItem wi) 
        throws ReplyException
    {
        //
        // [history] log the end of the [sub]flow
        
        historyLog(wi, History.EVT_FLOW_END, null, "replying");

        //
        // if there is a parent, reply to it
        
        if (getParent() != null) 
            replyToParent(wi);
        else
            //this.release();
            getExpressionPool().removeExpression(this);
    }

    /* *
     * Looks up for a variable value in the nearest 'process-definition' parent,
     * or in its parents if not found there.
     * This method overrides the one found in AbstractFlowExpression : 
     * this define expression ought to reply to the lookup.
     * /
    public Object lookupProcessVariable (final String variableName)
    {
        return lookupVariable(variableName);
    }
     */

    /**
     * Inits the expression.
     */
    public void init 
        (final ApplicationContext context,
         final FlowExpressionId parentId, 
         final FlowExpressionId id, 
         final RawExpression generatingExpression,
         final Object raw,
         final InFlowWorkItem currentWi)
    throws 
        BuildException
    {
        super.init
            (context, 
             parentId,
             id,
             generatingExpression,
             raw,
             currentWi);

        if (getChildren() == null) return;

        int bodyCount = 0;
        
        final java.util.Iterator it = getChildren().iterator();
        while (it.hasNext())
        {
            final FlowExpressionId fei = 
                (FlowExpressionId)it.next();

            final Class childClass = 
                getExpressionMap().getClass(fei.getExpressionName());

            if (childClass == null)
            {
                log.warn
                    ("init() "+id.getExpressionName()+
                     " unknown expression '"+fei.getExpressionName()+"'");
                continue;
            }

            if ( ! DefineExpression.class.isAssignableFrom(childClass))
                bodyCount++;

            if (bodyCount > 1)
            {
                log.warn
                    ("init() "+id.getExpressionName()+
                     " with more than one body");
                break;
            }
        }
    }

    //
    // STATIC METHODS

}