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/*-
* ============LICENSE_START=======================================================
* Copyright (C) 2016-2018 Ericsson. All rights reserved.
* Modifications Copyright (C) 2021 Bell Canada. All rights reserved.
* ================================================================================
* 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.
*
* SPDX-License-Identifier: Apache-2.0
* ============LICENSE_END=========================================================
*/
package org.onap.policy.apex.plugins.event.protocol.xml;
import java.io.ByteArrayInputStream;
import java.io.StringWriter;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import java.util.Map.Entry;
import javax.xml.XMLConstants;
import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;
import javax.xml.transform.stream.StreamSource;
import javax.xml.validation.Schema;
import javax.xml.validation.SchemaFactory;
import org.onap.policy.apex.plugins.event.protocol.xml.jaxb.ObjectFactory;
import org.onap.policy.apex.plugins.event.protocol.xml.jaxb.XMLApexEvent;
import org.onap.policy.apex.plugins.event.protocol.xml.jaxb.XMLApexEventData;
import org.onap.policy.apex.service.engine.event.ApexEvent;
import org.onap.policy.apex.service.engine.event.ApexEventException;
import org.onap.policy.apex.service.engine.event.ApexEventProtocolConverter;
import org.onap.policy.apex.service.engine.event.ApexEventRuntimeException;
import org.onap.policy.apex.service.parameters.eventprotocol.EventProtocolParameters;
import org.onap.policy.common.utils.resources.ResourceUtils;
import org.xml.sax.SAXException;
/**
* The Class Apex2XMLEventConverter converts {@link ApexEvent} instances into string instances of {@link XMLApexEvent}
* that are XML representations of Apex events defined in JAXB.
*
* @author Liam Fallon (liam.fallon@ericsson.com)
*/
public final class Apex2XmlEventConverter implements ApexEventProtocolConverter {
private static final String MODEL_SCHEMA_NAME = "xml/apex-event.xsd";
// XML Unmarshaller and marshaller and object factory for events
private Unmarshaller unmarshaller;
private Marshaller marshaller;
private ObjectFactory objectFactory = new ObjectFactory();
/**
* Constructor to create the Apex to XML converter.
*
* @throws ApexEventException the apex event exception
*/
public Apex2XmlEventConverter() throws ApexEventException {
try {
final URL schemaUrl = ResourceUtils.getUrlResource(MODEL_SCHEMA_NAME);
final Schema apexEventSchema =
SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI).newSchema(schemaUrl);
final JAXBContext jaxbContext = JAXBContext.newInstance(XMLApexEvent.class);
// Set up the unmarshaller to carry out validation
unmarshaller = jaxbContext.createUnmarshaller();
unmarshaller.setEventHandler(new javax.xml.bind.helpers.DefaultValidationEventHandler());
unmarshaller.setSchema(apexEventSchema);
// Set up the marshaller
marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
marshaller.setSchema(apexEventSchema);
} catch (JAXBException | SAXException e) {
throw new ApexEventException("Unable to set up marshalling and unmarshalling for XML events", e);
}
}
/**
* {@inheritDoc}.
*/
@Override
public void init(final EventProtocolParameters parameters) {
// No initialization necessary on this class
}
/**
* {@inheritDoc}.
*/
@Override
public List<ApexEvent> toApexEvent(final String eventName, final Object eventObject) throws ApexEventException {
// Check the XML event
if (eventObject == null) {
throw new ApexEventException("event processing failed, XML event is null");
}
// Cast the event to a string, if our conversion is correctly configured, this cast should always work
String xmlEventString = null;
try {
xmlEventString = (String) eventObject;
} catch (final Exception e) {
final String errorMessage = "error converting event \"" + eventObject + "\" to a string";
throw new ApexEventRuntimeException(errorMessage, e);
}
// The XML event
XMLApexEvent xmlApexEvent = null;
// Use JAXB to read and verify the event from the XML string
try {
final StreamSource source = new StreamSource(new ByteArrayInputStream(xmlEventString.getBytes()));
final JAXBElement<XMLApexEvent> rootElement = unmarshaller.unmarshal(source, XMLApexEvent.class);
xmlApexEvent = rootElement.getValue();
} catch (final JAXBException e) {
throw new ApexEventException("Unable to unmarshal Apex XML event\n" + xmlEventString, e);
}
// Create the Apex event
final ApexEvent apexEvent = new ApexEvent(xmlApexEvent.getName(), xmlApexEvent.getVersion(),
xmlApexEvent.getNameSpace(), xmlApexEvent.getSource(), xmlApexEvent.getTarget());
// Set the data on the apex event
for (final XMLApexEventData xmlData : xmlApexEvent.getData()) {
apexEvent.put(xmlData.getKey(), xmlData.getValue());
}
// Return the event in a single element
final ArrayList<ApexEvent> eventList = new ArrayList<>();
eventList.add(apexEvent);
return eventList;
}
/**
* {@inheritDoc}.
*/
@Override
public String fromApexEvent(final ApexEvent apexEvent) throws ApexEventException {
// Check the Apex event
if (apexEvent == null) {
throw new ApexEventException("event processing failed, Apex event is null");
}
// Get the Apex event data
final List<XMLApexEventData> xmlDataList = new ArrayList<>();
try {
for (final Entry<String, Object> apexDataEntry : apexEvent.entrySet()) {
// Add an XML event data item
if (apexDataEntry.getValue() != null) {
xmlDataList.add(new XMLApexEventData(apexDataEntry.getKey(), apexDataEntry.getValue().toString()));
} else {
xmlDataList.add(new XMLApexEventData(apexDataEntry.getKey(), ""));
}
}
} catch (final Exception e) {
throw new ApexEventException("Unable to transfer Apex event data to XML\n" + apexEvent, e);
}
// Create the XML event
final XMLApexEvent xmlApexEvent = new XMLApexEvent(apexEvent.getName(), apexEvent.getVersion(),
apexEvent.getNameSpace(), apexEvent.getSource(), apexEvent.getTarget(), xmlDataList);
// Write the event into a DOM document
try {
// Marshal the event into XML
final StringWriter writer = new StringWriter();
marshaller.marshal(objectFactory.createXmlApexEvent(xmlApexEvent), writer);
// Return the event as XML in a string
return writer.toString();
} catch (final JAXBException e) {
throw new ApexEventException("Unable to unmarshal Apex event to XML\n" + apexEvent, e);
}
}
}
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