/*
* Autopsy Forensic Browser
*
* Copyright 2011-2015 Basis Technology Corp.
* Contact: carrier <at> sleuthkit <dot> org
*
* 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.sleuthkit.autopsy.events;
import java.beans.PropertyChangeListener;
import java.net.URISyntaxException;
import java.util.Set;
import java.util.logging.Level;
import javax.jms.JMSException;
import org.sleuthkit.autopsy.core.UserPreferencesException;
import org.sleuthkit.autopsy.core.UserPreferences;
import org.sleuthkit.autopsy.coreutils.Logger;
/**
* Provides thread-safe support for publishing events to registered subscribers
* on both this Autopsy node and other Autopsy nodes. Subscribers are
* constrained to be PropertyChangeListeners to integrate with the legacy use of
* JavaBeans PropertyChangeEvents and PropertyChangeListeners as an application
* event system.
*/
public final class AutopsyEventPublisher {
/**
* Composed of thread-safe objects.
*/
private static final Logger logger = Logger.getLogger(AutopsyEventPublisher.class.getName());
private static final int MAX_REMOTE_EVENT_PUBLISH_TRIES = 1;
private final LocalEventPublisher localPublisher;
private RemoteEventPublisher remotePublisher;
private String currentChannelName;
/**
* Constructs an object for publishing events to registered subscribers on
* both this Autopsy node and other Autopsy nodes. Communication with other
* nodes is not turned on by default - call openRemoteEventChannel() after
* construction.
*/
public AutopsyEventPublisher() {
localPublisher = new LocalEventPublisher();
}
/**
* Opens the event channel used for publishing events to and receiving
* events from other Autopsy nodes. Only one channel may be open at a time.
*
* @param channelName The name of the event channel.
*
* @throws AutopsyEventException if the channel was not opened.
*/
public void openRemoteEventChannel(String channelName) throws AutopsyEventException {
currentChannelName = channelName;
if (null != remotePublisher) {
closeRemoteEventChannel();
}
try {
remotePublisher = new RemoteEventPublisher(channelName, localPublisher, UserPreferences.getMessageServiceConnectionInfo());
} catch (URISyntaxException | JMSException ex) {
String message = "Failed to open remote event channel"; //NON-NLS
logger.log(Level.SEVERE, message, ex);
throw new AutopsyEventException(message, ex);
} catch (UserPreferencesException ex) {
String message = "Error accessing messaging service connection info"; //NON-NLS
logger.log(Level.SEVERE, message, ex);
throw new AutopsyEventException(message, ex);
}
}
/**
* Closes the event channel used for publishing events to and receiving
* events from other Autopsy nodes.
*/
public void closeRemoteEventChannel() {
stopRemotePublisher();
currentChannelName = null;
}
/**
* Adds an event subscriber to this publisher.
*
* @param eventNames The events the subscriber is interested in.
* @param subscriber The subscriber to add.
*/
public void addSubscriber(Set<String> eventNames, PropertyChangeListener subscriber) {
localPublisher.addSubscriber(eventNames, subscriber);
}
/**
* Adds an event subscriber to this publisher.
*
* @param eventName The event the subscriber is interested in.
* @param subscriber The subscriber to add.
*/
public void addSubscriber(String eventName, PropertyChangeListener subscriber) {
localPublisher.addSubscriber(eventName, subscriber);
}
/**
* Removes an event subscriber from this publisher.
*
* @param eventNames The events the subscriber is no longer interested in.
* @param subscriber The subscriber to remove.
*/
public void removeSubscriber(Set<String> eventNames, PropertyChangeListener subscriber) {
localPublisher.removeSubscriber(eventNames, subscriber);
}
/**
* Removes an event subscriber from this publisher.
*
* @param eventName The event the subscriber is no longer interested in.
* @param subscriber The subscriber to remove.
*/
public void removeSubscriber(String eventName, PropertyChangeListener subscriber) {
localPublisher.removeSubscriber(eventName, subscriber);
}
/**
* Publishes an event to this Autopsy node and other Autopsy nodes.
*
* @param event The event to publish.
*/
public void publish(AutopsyEvent event) {
publishLocally(event);
publishRemotely(event);
}
/**
* Publishes an event to this Autopsy node only.
*
* @param event The event to publish.
*/
public void publishLocally(AutopsyEvent event) {
localPublisher.publish(event);
}
/**
* Publishes an event to other Autopsy nodes only.
*
* @param event The event to publish.
*/
public void publishRemotely(AutopsyEvent event) {
if (null != currentChannelName) {
boolean published = false;
int tryCount = 1;
while (false == published && tryCount <= MAX_REMOTE_EVENT_PUBLISH_TRIES) {
try {
if (null == remotePublisher) {
openRemoteEventChannel(currentChannelName);
}
remotePublisher.publish(event);
published = true;
} catch (AutopsyEventException | JMSException ex) {
logger.log(Level.SEVERE, String.format("Failed to publish %s using channel %s (tryCount = %s)", event.getPropertyName(), currentChannelName, tryCount), ex); //NON-NLS
stopRemotePublisher();
++tryCount;
}
}
}
}
/**
* Stops the remote event publisher, but does not reset the current channel
* name.
*/
private void stopRemotePublisher() {
if (null != remotePublisher) {
try {
remotePublisher.stop();
} catch (JMSException ex) {
logger.log(Level.SEVERE, String.format("Error closing remote event publisher for channel %s", currentChannelName), ex); //NON-NLS
}
remotePublisher = null;
}
}
}