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Implements the JSR-94 API with Drools.
There is a newer version: 7.2.0.Final
/*
 * Copyright 2005 Red Hat, Inc. and/or its affiliates.
 * 
 * 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.drools.jsr94.rules;

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

import javax.rules.RuleExecutionSetNotFoundException;
import javax.rules.RuleRuntime;
import javax.rules.RuleSession;
import javax.rules.RuleSessionCreateException;
import javax.rules.RuleSessionTypeUnsupportedException;

import org.drools.jsr94.rules.repository.RuleExecutionSetRepository;
import org.drools.jsr94.rules.repository.RuleExecutionSetRepositoryException;

/**
 * The Drools implementation of the RuleRuntime interface which
 * is the access point for runtime execution of RuleExecutionSets.
 * It provides methods to create RuleSession implementation as
 * well as methods to retrieve RuleExecutionSets that have been
 * previously registered using the RuleAdministrator.  The
 * RuleRuntime should be accessed through the
 * RuleServiceProvider. An instance of the
 * RuleRuntime can be retrieved by calling: 
 
 * RuleServiceProvider ruleServiceProvider =
 *     RuleServiceProvider.newInstance();

 * RuleRuntime ruleRuntime = ruleServiceProvider.getRuleRuntime();
 * 
 *  Note: the release method must be called on the RuleSession
 * to clean up all resources used by the RuleSession.
 * 
 * @see RuleRuntime
 */
public class RuleRuntimeImpl
    implements
    RuleRuntime {
    private static final long          serialVersionUID = 510l;

    private RuleExecutionSetRepository repository;

    /**
     * Create a new RuleRuntimeImpl.
     */
    public RuleRuntimeImpl(final RuleExecutionSetRepository repository) {
        this.repository = repository;
        // no special initialization required
    }

    /**
     * Creates a RuleSession implementation using the supplied
     * Drools-specific rule execution set registration URI.
     * 
     * @param uri
     *            the URI for the RuleExecutionSet
     * @param properties
     *            additional properties used to create the
     *            RuleSession implementation.
     * @param ruleSessionType
     *            the type of rule session to create.
     * 
     * @throws RuleSessionTypeUnsupportedException
     *             if the ruleSessionType is not supported by Drools or the
     *             RuleExecutionSet
     * @throws RuleExecutionSetNotFoundException
     *             if the URI could not be resolved into a
     *             RuleExecutionSet
     * 
     * @return The created RuleSession.
     */
    public RuleSession createRuleSession(final String uri,
                                         final Map properties,
                                         final int ruleSessionType)
    throws RuleSessionTypeUnsupportedException,
           RuleSessionCreateException,
           RuleExecutionSetNotFoundException {

        if ( ruleSessionType == RuleRuntime.STATELESS_SESSION_TYPE ) {
            final StatelessRuleSessionImpl session = new StatelessRuleSessionImpl( uri,
                                                                                   properties,
                                                                                   this.repository );
            return session;
        } else if ( ruleSessionType == RuleRuntime.STATEFUL_SESSION_TYPE ) {
            final StatefulRuleSessionImpl session = new StatefulRuleSessionImpl( uri,
                                                                                 properties,
                                                                                 this.repository );
            return session;
        }

        throw new RuleSessionTypeUnsupportedException( "invalid session type: " + ruleSessionType );
    }

    /**
     * Retrieves a List of the URIs that currently have
     * RuleExecutionSets associated with them. An empty list is
     * returned is there are no associations.
     * 
     * @return a List of Strings (URIs)
     */
    public List getRegistrations() {
        try {
            return this.repository.getRegistrations();
        } catch (RuleExecutionSetRepositoryException e) {
            String s = "Error while retrieving list of registrations";
            throw new RuntimeException(s, e);
        }
    }
}