/*
* Copyright 2015 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.wso2.carbon.registry.event.core.internal.builder;
import org.wso2.carbon.registry.event.core.EventBroker;
import org.wso2.carbon.registry.event.core.EventBrokerFactory;
import org.wso2.carbon.registry.event.core.exception.EventBrokerConfigurationException;
import org.wso2.carbon.registry.event.core.util.EventBrokerConstants;
import org.wso2.carbon.utils.CarbonUtils;
import org.wso2.carbon.utils.ServerConstants;
import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.impl.builder.StAXOMBuilder;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.namespace.QName;
import java.io.*;
/**
* Start point to build the event broker. This class read the event broker file and calls the
* event broker factory class to create event broker
*/
public class EventBrokerBuilder {
public static EventBroker createEventBroker() throws EventBrokerConfigurationException {
OMElement ebConfig = loadConfigXML();
if (!ebConfig.getQName().equals(
new QName(EventBrokerConstants.EB_CONF_NAMESPACE, EventBrokerConstants.EB_CONF_ELE_ROOT))) {
throw new EventBrokerConfigurationException("Invalid root element in event broker config");
}
OMElement eventBroker =
ebConfig.getFirstChildWithName(new QName(EventBrokerConstants.EB_CONF_NAMESPACE,
EventBrokerConstants.EB_CONF_ELE_EVENT_BROKER));
String className =
eventBroker.getAttributeValue(new QName(null, EventBrokerConstants.EB_CONF_ATTR_CLASS));
try {
Class brokerImplClass = Class.forName(className);
EventBrokerFactory eventBrokerFactory =
(EventBrokerFactory) brokerImplClass.newInstance();
return eventBrokerFactory.getEventBroker(eventBroker);
} catch (ClassNotFoundException e) {
throw new EventBrokerConfigurationException("Can not load the class " + className, e);
} catch (IllegalAccessException e) {
throw new EventBrokerConfigurationException("Can not access the class " + className, e);
} catch (InstantiationException e) {
throw new EventBrokerConfigurationException("Can not instantiate the class " + className, e);
}
}
/**
* Helper method to load the event config
*
* @return OMElement representation of the event config
*/
private static OMElement loadConfigXML() throws EventBrokerConfigurationException {
String path = CarbonUtils.getCarbonConfigDirPath() + File.separator + EventBrokerConstants.EB_CONF;
BufferedInputStream inputStream = null;
try {
inputStream = new BufferedInputStream(new FileInputStream(new File(path)));
XMLStreamReader parser = XMLInputFactory.newInstance().
createXMLStreamReader(inputStream);
StAXOMBuilder builder = new StAXOMBuilder(parser);
OMElement omElement = builder.getDocumentElement();
omElement.build();
return omElement;
} catch (FileNotFoundException e) {
throw new EventBrokerConfigurationException(EventBrokerConstants.EB_CONF
+ "cannot be found in the path : " + path, e);
} catch (XMLStreamException e) {
throw new EventBrokerConfigurationException("Invalid XML for " + EventBrokerConstants.EB_CONF
+ " located in the path : " + path, e);
} finally {
try {
if (inputStream != null) {
inputStream.close();
}
} catch (IOException ingored) {
throw new EventBrokerConfigurationException("Can not close the input stream");
}
}
}
}