Refine local/remote events system infrastructure and IngestManager use of it

Core/src/org/sleuthkit/autopsy/events/AutopsyEventException.java

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+/*
+ * Autopsy Forensic Browser
+ *
+ * Copyright 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 javax.annotation.concurrent.Immutable;
+
+/**
+ * Provides a generic events system exception for clients of the events package.
+ */
+@Immutable
+public final class AutopsyEventException extends Exception {
+
+    /**
+     * Constructs a new exception with null as its message.
+     */
+    AutopsyEventException() {
+        super();
+    }
+
+    /**
+     * Constructs a new exception with the specified message.
+     *
+     * @param message The message.
+     */
+    AutopsyEventException(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructs a new exception with the specified message and cause.
+     *
+     * @param message The message.
+     * @param cause The cause.
+     */
+    AutopsyEventException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+}

Core/src/org/sleuthkit/autopsy/events/AutopsyEventPublisher.java

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+/*
+ * Autopsy Forensic Browser
+ *
+ * Copyright 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.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 {
+    
+    private static final Logger logger = Logger.getLogger(AutopsyEventPublisher.class.getName());
+    private final LocalEventPublisher localPublisher;
+    private RemoteEventPublisher remotePublisher;
+
+    /**
+     * 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.
+     */
+    synchronized public void openRemoteEventChannel(String channelName) throws AutopsyEventException {
+        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); 
+        }
+    }
+
+    /**
+     * Closes the event channel used for publishing events to and receiving
+     * events from other Autopsy nodes.
+     */
+    synchronized public void closeRemoteEventChannel() {
+        if (null != remotePublisher) {
+            try {
+                remotePublisher.stop();
+            } catch (JMSException ex) {
+                logger.log(Level.SEVERE, "Error closing remote event channel", ex); //NON-NLS
+            }
+            remotePublisher = null;
+        }
+    }
+
+    /**
+     * Adds an event subscriber to this publisher.
+     *
+     * @param eventNames The events the subscriber is interested in.
+     * @param subscriber The subscriber to add.
+     */
+    synchronized 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.
+     */
+    synchronized 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.
+     */
+    synchronized public void removeSubscriber(Set<String> eventNames, PropertyChangeListener subscriber) {
+        localPublisher.removeSubscriber(eventNames, subscriber);
+    }
+
+    /**
+     * Removes an event subscriber from this publisher.
+     *
+     * @param eventNames The event the subscriber is no longer interested in.
+     * @param subscriber The subscriber to remove.
+     */
+    synchronized public void removeSubscriber(String eventName, PropertyChangeListener subscriber) {
+        localPublisher.removeSubscriber(eventName, subscriber);
+    }
+
+    /**
+     * Publishes an event.
+     *
+     * @param event The event to publish.
+     * @throws JMSException
+     */
+    synchronized public void publish(AutopsyEvent event) throws JMSException {
+        event.setSourceType(AutopsyEvent.SourceType.LOCAL);
+        localPublisher.publish(event);
+        if (null != remotePublisher) {
+            event.setSourceType(AutopsyEvent.SourceType.REMOTE);
+            remotePublisher.send(event);
+        }
+    }
+
+}