statelessrulesessionimpl.java

drools 一个开放源码的规则引擎

package org.drools.jsr94.rules;

/*
 * $Id: StatelessRuleSessionImpl.java,v 1.13 2006/01/16 01:31:22 michaelneale Exp $
 *
 * Copyright 2002-2004 (C) The Werken Company. All Rights Reserved.
 *
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 *
 * 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 name "drools" must not be used to endorse or promote products derived
 * from this Software without prior written permission of The Werken Company.
 * For written permission, please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "drools" nor may
 * "drools" appear in their names without prior written permission of The Werken
 * Company. "drools" is a registered trademark of The Werken Company.
 *
 * 5. Due credit should be given to The Werken Company.
 * (http://drools.werken.com/).
 *
 * THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS ``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 WERKEN COMPANY OR ITS 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.
 *
 */

import java.util.Iterator;
import java.util.List;
import java.util.Map;

import javax.rules.InvalidRuleSessionException;
import javax.rules.ObjectFilter;
import javax.rules.RuleExecutionSetNotFoundException;
import javax.rules.StatelessRuleSession;

import org.drools.FactException;
import org.drools.WorkingMemory;
import org.drools.jsr94.rules.admin.RuleExecutionSetImpl;
import org.drools.jsr94.rules.admin.RuleExecutionSetRepository;

/**
 * The Drools implementation of the <code>StatelessRuleSession</code>
 * interface which is a representation of a stateless rules engine session. A
 * stateless rules engine session exposes a stateless rule execution API to an
 * underlying rules engine.
 * 
 * @see StatelessRuleSession
 * 
 * @author <a href="mailto:[e-mail]">thomas diesler </a>
 */
public class StatelessRuleSessionImpl extends AbstractRuleSessionImpl implements
		StatelessRuleSession {
	/**
	 * Gets the <code>RuleExecutionSet</code> for this URI and associates it
	 * with a RuleBase.
	 * 
	 * @param bindUri
	 *            the URI the <code>RuleExecutionSet</code> has been bound to
	 * @param properties
	 *            additional properties used to create the
	 *            <code>RuleSession</code> implementation.
	 * 
	 * @throws RuleExecutionSetNotFoundException
	 *             if there is no rule set under the given URI
	 */
	StatelessRuleSessionImpl(String bindUri, Map properties,
			RuleExecutionSetRepository repository)
			throws RuleExecutionSetNotFoundException {
		super(repository);
		this.setProperties(properties);

		RuleExecutionSetImpl ruleSet = (RuleExecutionSetImpl) repository
				.getRuleExecutionSet(bindUri);

		if (ruleSet == null) {
			throw new RuleExecutionSetNotFoundException(
					"RuleExecutionSet unbound: " + bindUri);
		}

		this.setRuleExecutionSet(ruleSet);
	}

	/**
	 * Executes the rules in the bound rule execution set using the supplied
	 * list of objects. A <code>List</code> is returned containing the objects
	 * created by (or passed into the rule session) the executed rules that pass
	 * the filter test of the default <code>RuleExecutionSet</code>
	 * <code>ObjectFilter</code>
	 * (if present). <p/> The returned list may not neccessarily include all
	 * objects passed, and may include <code>Object</code>s created by
	 * side-effects. The execution of a <code>RuleExecutionSet</code> can add,
	 * remove and update objects. Therefore the returned object list is
	 * dependent on the rules that are part of the executed
	 * <code>RuleExecutionSet</code> as well as Drools specific rule engine
	 * behavior.
	 * 
	 * @param objects
	 *            the objects used to execute rules.
	 * 
	 * @return a <code>List</code> containing the objects as a result of
	 *         executing the rules.
	 * 
	 * @throws InvalidRuleSessionException
	 *             on illegal rule session state.
	 */
	public List executeRules(List objects) throws InvalidRuleSessionException {
		return this.executeRules(objects, this.getRuleExecutionSet()
				.getObjectFilter());
	}

	/**
	 * Executes the rules in the bound rule execution set using the supplied
	 * list of objects. A <code>List</code> is returned containing the objects
	 * created by (or passed into the rule engine) the executed rules and
	 * filtered with the supplied object filter. <p/> The returned list may not
	 * neccessarily include all objects passed, and may include
	 * <code>Object</code>s created by side-effects. The execution of a
	 * <code>RuleExecutionSet</code> can add, remove and update objects.
	 * Therefore the returned object list is dependent on the rules that are
	 * part of the executed <code>RuleExecutionSet</code> as well as Drools
	 * specific rule engine behavior.
	 * 
	 * @param objects
	 *            the objects used to execute rules.
	 * @param filter
	 *            the object filter.
	 * 
	 * @return a <code>List</code> containing the objects as a result of
	 *         executing rules, after passing through the supplied object
	 *         filter.
	 * 
	 * @throws InvalidRuleSessionException
	 *             on illegal rule session state.
	 */
	public List executeRules(List objects, ObjectFilter filter)
			throws InvalidRuleSessionException {
		WorkingMemory workingMemory = this.newWorkingMemory();

		try {
			for (Iterator objectIter = objects.iterator(); objectIter.hasNext();) {
				workingMemory.assertObject(objectIter.next());
			}

			workingMemory.fireAllRules();
		} catch (FactException e) {
			throw new InvalidRuleSessionException(e.getMessage(), e);
		}

		List results = workingMemory.getObjects();

		this.applyFilter(results, filter);

		return results;
	}
}