/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.wso2.carbon.rule.service;
import org.apache.axis2.context.MessageContext;
import org.apache.axis2.context.ServiceContext;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.wso2.carbon.rule.core.RuleConstants;
import org.wso2.carbon.rule.core.Session;
import org.wso2.carbon.rule.server.RuleEngine;
import org.wso2.carbon.rulecep.adapters.InputManager;
import org.wso2.carbon.rulecep.commons.descriptions.rule.SessionDescription;
import java.util.ArrayList;
import java.util.List;
/**
* Invokes the rule engine with facts and returns results
*/
public class RuleServiceInvoker {
private static final Log log = LogFactory.getLog(RuleServiceInvoker.class);
/**
* Access facade to rule service provider
*/
private RuleEngine ruleEngine;
/**
* To formulate the facts from the Axis2 Message Context
*/
private InputManager inputManager;
/**
* Information about the session - the default is a stateless session
*/
private SessionDescription sessionDescription;
/**
* The previous expired session
*/
// private Session lastSession; TODO add proper session clean up
/* Lock used to ensure thread-safe creation of the rule session*/
private final Object resourceLock = new Object();
public RuleServiceInvoker(RuleEngine ruleEngine,
InputManager inputManager,
SessionDescription sessionDescription) {
this.ruleEngine = ruleEngine;
this.inputManager = inputManager;
this.sessionDescription = sessionDescription;
}
/**
* Extracts the facts from the request message and inserts into the rule engine and then executes
* the rule engine.
* Returns if there any results
*
* @param requestMessageContext request message
* @return A list containing results of rule engine execution
*/
public List invoke(MessageContext requestMessageContext) {
Session session;
if (!sessionDescription.isStateful()) {
session = ruleEngine.createSession(sessionDescription);
} else {
ServiceContext serviceContext =
requestMessageContext.getServiceContext();
session = (Session) serviceContext.getProperty(RuleConstants.RULE_SESSION);
if (session == null) {
synchronized (resourceLock) {
session = (Session) serviceContext.getProperty(RuleConstants.RULE_SESSION);
if (session == null) { // double check
session = ruleEngine.createSession(sessionDescription);
serviceContext.setProperty(RuleConstants.RULE_SESSION, session);
}
}
}
}
List<Object> facts = inputManager.processInputs(requestMessageContext);
if (!facts.isEmpty()) {
List results = session.execute(facts);
if (!sessionDescription.isStateful()) {
session.release();
}
return results;
} else {
if (log.isDebugEnabled()) {
log.debug("There is no facts to be injected into the rule engine");
}
return new ArrayList();
}
}
}