/**
* 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
* <p/>
* http://www.apache.org/licenses/LICENSE-2.0
* <p/>
* 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.apache.hadoop.gateway.ha.provider;
import org.apache.hadoop.gateway.ha.provider.impl.DefaultHaProvider;
import org.apache.hadoop.gateway.ha.provider.impl.HaDescriptorManager;
import org.apache.hadoop.gateway.ha.provider.impl.i18n.HaMessages;
import org.apache.hadoop.gateway.i18n.messages.MessagesFactory;
import org.apache.hadoop.gateway.services.GatewayServices;
import org.apache.hadoop.gateway.services.registry.ServiceRegistry;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
public class HaServletContextListener implements ServletContextListener {
public static final String PROVIDER_ATTRIBUTE_NAME = HaProvider.class.getName();
public static final String DESCRIPTOR_LOCATION_INIT_PARAM_NAME = "haDescriptorLocation";
public static final String DESCRIPTOR_DEFAULT_FILE_NAME = "ha.xml";
public static final String DESCRIPTOR_DEFAULT_LOCATION = "/WEB-INF/" + DESCRIPTOR_DEFAULT_FILE_NAME;
private static final HaMessages LOG = MessagesFactory.get(HaMessages.class);
@Override
public void contextInitialized(ServletContextEvent event) {
HaDescriptor descriptor;
ServletContext servletContext = event.getServletContext();
try {
URL url = locateDescriptor(servletContext);
descriptor = loadDescriptor(url);
} catch (IOException e) {
throw new IllegalStateException(e);
}
setupHaProvider(descriptor, servletContext);
}
@Override
public void contextDestroyed(ServletContextEvent event) {
event.getServletContext().removeAttribute(PROVIDER_ATTRIBUTE_NAME);
}
public static HaProvider getHaProvider(ServletContext context) {
return (HaProvider) context.getAttribute(PROVIDER_ATTRIBUTE_NAME);
}
private void setupHaProvider(HaDescriptor descriptor, ServletContext servletContext) {
GatewayServices services = (GatewayServices) servletContext.getAttribute(GatewayServices.GATEWAY_SERVICES_ATTRIBUTE);
String clusterName = (String) servletContext.getAttribute(GatewayServices.GATEWAY_CLUSTER_ATTRIBUTE);
ServiceRegistry serviceRegistry = services.getService(GatewayServices.SERVICE_REGISTRY_SERVICE);
HaProvider provider = new DefaultHaProvider(descriptor);
List<String> serviceNames = descriptor.getEnabledServiceNames();
for (String serviceName : serviceNames) {
provider.addHaService(serviceName, serviceRegistry.lookupServiceURLs(clusterName, serviceName));
}
servletContext.setAttribute(PROVIDER_ATTRIBUTE_NAME, provider);
}
private static URL locateDescriptor(ServletContext context) throws IOException {
String param = context.getInitParameter(DESCRIPTOR_LOCATION_INIT_PARAM_NAME);
if (param == null) {
param = DESCRIPTOR_DEFAULT_LOCATION;
}
URL url;
try {
url = context.getResource(param);
} catch (MalformedURLException e) {
// Ignore it and try using the value directly as a URL.
url = null;
}
if (url == null) {
url = new URL(param);
}
if (url == null) {
throw new FileNotFoundException(param);
}
return url;
}
private static HaDescriptor loadDescriptor(URL url) throws IOException {
InputStream stream = url.openStream();
HaDescriptor descriptor = HaDescriptorManager.load(stream);
try {
stream.close();
} catch (IOException e) {
LOG.failedToLoadHaDescriptor(e);
}
return descriptor;
}
}