/**
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "Exolab" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Exoffice Technologies. For written permission,
* please contact info@exolab.org.
*
* 4. Products derived from this Software may not be called "Exolab"
* nor may "Exolab" appear in their names without prior written
* permission of Exoffice Technologies. Exolab is a registered
* trademark of Exoffice Technologies.
*
* 5. Due credit should be given to the Exolab Project
* (http://www.exolab.org/).
*
* THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Copyright 2001-2005 (C) Exoffice Technologies Inc. All Rights Reserved.
*/
package org.exolab.jms.messagemgr;
import javax.jms.InvalidSelectorException;
import javax.jms.JMSException;
import org.exolab.jms.client.JmsDestination;
import org.exolab.jms.message.MessageImpl;
import org.exolab.jms.selector.Selector;
/**
* Abstract implementation of the {@link ConsumerEndpoint} interface.
*
* @author <a href="mailto:jima@exoffice.com">Jim Alateras</a>
* @author <a href="mailto:tma@netspace.net.au">Tim Anderson</a>
* @version $Revision: 1.3 $ $Date: 2005/08/30 06:25:47 $
*/
public abstract class AbstractConsumerEndpoint implements ConsumerEndpoint {
/**
* The identity of this consumer.
*/
private final long _id;
/**
* The destination the consumer is acceesing.
*/
private final JmsDestination _destination;
/**
* The message selector associated with this consumer. May be
* <code>null</code>.
*/
private Selector _selector;
/**
* If true, and the destination is a topic, inhibits the delivery of
* messages published by its own connection.
*/
private boolean _noLocal;
/**
* Determines if this consumer is asynchronous.
*/
private boolean _asynchronous = false;
/**
* The receive timeout, if the client is performing a blocking receive. A
* value of <code>0</code> indicates the client is blocking indefinitely.
*/
private Condition _waitingForMessage;
/**
* The listener to notify when a message is available.
*/
private ConsumerEndpointListener _listener = null;
/**
* Determines if this is (or is in the process of being) closed.
*/
private final Flag _closed = new Flag(false);
/**
* Construct a new <code>ConsumerEndpoint</code>.
* <p/>
* The destination and selector determine where it will be sourcing its
* messages from, and scheduler is used to asynchronously deliver messages
* to the consumer.
*
* @param consumerId the identity of this consumer
* @param destination the destination to access
* @param selector the message selector. May be <code>null</code>
* @param noLocal if true, and the destination is a topic, inhibits the
* delivery of messages published by its own connection.
* @throws InvalidSelectorException if the selector is not well formed
*/
public AbstractConsumerEndpoint(long consumerId, JmsDestination destination,
String selector, boolean noLocal)
throws InvalidSelectorException {
if (destination == null) {
throw new IllegalArgumentException(
"Argument 'destination' is null");
}
_id = consumerId;
_destination = destination;
setSelector(selector);
_noLocal = noLocal;
}
/**
* Returns the identity of this consumer.
*
* @return the identity of this consumer
*/
public long getId() {
return _id;
}
/**
* Determines if this is a persistent or non-persistent consumer.
* <p/>
* If persistent, then the consumer is persistent accross subscriptions and
* server restarts, and {@link #getPersistentId} returns a non-null value.
*
* @return <code>false</code>
*/
public boolean isPersistent() {
return false;
}
/**
* Returns the persistent identifier for this consumer. This is the identity
* of the consumer which is persistent across subscriptions and server
* restarts.
*
* @return <code>null</code>
*/
public String getPersistentId() {
return null;
}
/**
* Return the destination that this consumer is accessing.
*
* @return the destination that this consumer is accessing
*/
public JmsDestination getDestination() {
return _destination;
}
/**
* Determines if this consumer can consume messages from the specified
* destination.
*
* @param destination the destination
* @return <code>true</code> if the consumer can consume messages from
* <code>destination</code>; otherwise <code>false</code>
*/
public boolean canConsume(JmsDestination destination) {
return _destination.equals(destination);
}
/**
* Returns the message selector.
*
* @return the message selector, or <code>null</code> if none was specified
* by the client
*/
public Selector getSelector() {
return _selector;
}
/**
* Determines if a message is selected by the consumer.
*
* @param message the message to check
* @return <code>true</code> if the message is selected; otherwise
* <code>false</code>
*/
public boolean selects(MessageImpl message) {
return (_selector == null || _selector.selects(message));
}
/**
* Returns if locally produced messages are being inhibited.
*
* @return <code>true</code> if locally published messages are being
* inhibited.
*/
public boolean getNoLocal() {
return _noLocal;
}
/**
* Return the next available message to the client.
*
* @param cancel
* @return the next message, or <code>null</code> if none is available
* @throws JMSException for any error
*/
public final synchronized MessageHandle receive(final Condition cancel)
throws JMSException {
MessageHandle result = null;
if (!_closed.get()) {
Condition condition = new Condition() {
public boolean get() {
return _closed.get() || cancel.get();
}
};
result = doReceive(condition);
}
return result;
}
/**
* Indicates if this is an asynchronous consumer.
* <p/>
* An asynchronous consumer has a client <code>MessageConsumer</code> with
* an associated <code>MessageListener</code>.
*
* @param asynchronous if <code>true</code> marks this as an asynchronous
* consumer
*/
public synchronized void setAsynchronous(boolean asynchronous) {
_asynchronous = asynchronous;
}
/**
* Determines if this is an asynchronous consumer.
*
* @return <code>true</code> if this is an asynchronous consumer; otherwise
* <code>false</code>
*/
public synchronized boolean isAsynchronous() {
return _asynchronous;
}
/**
* Indicates that the client is currently waiting for a message.
*
* @param condition the condition to evaluate to determine if the client is
* waiting for message. May be <code>null</code>.
*/
public synchronized void setWaitingForMessage(Condition condition) {
_waitingForMessage = condition;
}
/**
* Determines if the client is currently waiting for a message.
*
* @return <code>true</code> if the client is waiting for messages;
* otherwise <code>false</code>
*/
public synchronized boolean isWaitingForMessage() {
return _waitingForMessage != null && _waitingForMessage.get();
}
/**
* Set the listener for this consumer. If a listener is set, it is notified
* when messages become available.
*
* @param listener the listener to add, or <code>null</code> to remove an
* existing listener
*/
public synchronized void setListener(ConsumerEndpointListener listener) {
_listener = listener;
}
/**
* Determines if this consumer is closed, or in the process of being
* closed.
*
* @return <code>true</code> if this consumer is closed; otherwise
* <code>false</code>
*/
public final boolean isClosed() {
return _closed.get();
}
/**
* Close this endpoint.
*/
public final void close() {
_closed.set(true);
synchronized (this) {
_listener = null;
doClose();
}
}
/**
* Returns a stringified version of the consumer.
*
* @return a stringified version of the consumer
*/
public String toString() {
return _id + ":" + getDestination();
}
/**
* Return the next available message to the client.
* <p/>
* This method will not be invoked if the consumer is being closed, however
* it is possible for {@link #close()} to be invoked while this method is in
* progress. Implementations should therefore invoke isClosed() to determine
* if the consumer is in the process of being closed, and if so, return
* <code>null</code>.
*
* @param cancel
* @return the next message, or <code>null</code> if none is available
* @throws JMSException for any error
*/
protected abstract MessageHandle doReceive(Condition cancel)
throws JMSException;
/**
* Closes the endpoint.
*/
protected abstract void doClose();
/**
* Notify the listener that a message is available for this consumer.
*/
protected synchronized void notifyMessageAvailable() {
if (_listener != null && !_closed.get()) {
_listener.messageAvailable(this);
}
}
/**
* Sets the message selector.
*
* @param selector the message selector. May be <code>null</code>
* @throws InvalidSelectorException if the selector is not well formed
*/
protected void setSelector(String selector)
throws InvalidSelectorException {
_selector = (selector != null) ? new Selector(selector) : null;
}
/**
* Determines if locally produced messages are being inhibited.
*
* @param noLocal if <code>true</code>, locally published messages are
* inhibited.
*/
protected void setNoLocal(boolean noLocal) {
_noLocal = noLocal;
}
}