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   // $Header: /cvsroot/daoexamples/daoexamples/src/java/daoexamples/moviedemo/MessagePublisher.java,v 1.3 2003/08/12 04:41:02 sullis Exp $
    
   /*
    * 
    *
    * 
    * 
    */
    
  package daoexamples.moviedemo;
  
  import daoexamples.exception.*;
  import javax.jms.*;
  import javax.naming.*;
  import javax.rmi.PortableRemoteObject;
  import org.apache.commons.logging.*;
  
  /***
   *
   * publishes messages to a JMS Topic
   *
   * You can learn more about the Java Message Service at  
   * <a href="http://java.sun.com/products/jms/">http://java.sun.com/products/jms/</a>
   * 
   * This class assumes that transactions are externally 
   * demaracated using JTA
   *
   * Instances of this class are not thread-safe.
   *    
   * @author Sean C. Sullivan
   * 
   */
  class MessagePublisher
  {
  	static private final Log log = LogFactory.getLog(MessagePublisher.class);
  	static private final String TOPIC_CF_JNDI_NAME = "java:comp/env/jms/MovieTCF";
  	static private final String TOPIC_JNDI_NAME = "java:comp/env/jms/MovieTopic";
  	
  	private TopicConnection tconn;
  	private TopicSession tsess;
  	private TopicPublisher publisher;
  	private Topic top;
  	private boolean bIsClosed = false;
  
  	/***
  	 *  
  	 * Before calling this constructor, you must have 
  	 * a JTA UserTransaction
  	 *
  	 * @throws daoexamples.exception.DAORuntimeException
  	 * 
  	 */
  	public MessagePublisher()
  	{
  		try
  		{
  			tconn = getTopicConnection();
  			tsess = tconn.createTopicSession(
  								true /* true == session is transacted */, 
  								TopicSession.AUTO_ACKNOWLEDGE);
  			top = getTopic();
  			publisher = tsess.createPublisher(top);
  		}
  		catch (JMSException ex)
  		{
  			throw new DAORuntimeException(ex);
  		}
  			
  	}
  
     /***
      * 	
  	* @throws daoexamples.exception.DAORuntimeException
  	* 
  	*/
  	static private InitialContext getInitialContext()
  	{
  	
  		InitialContext ctx = null;
  		
  		try
  		{
  			ctx = new InitialContext();
  		}
  		catch (NamingException ex)
  		{
  			throw new DAORuntimeException(ex);
  		}
  	
  		return ctx;
  	
  	}
  	
  	/***
  	 * 	
  	 * @throws daoexamples.exception.DAORuntimeException
  	 * 
  	 */
  	static private Topic getTopic()
 	{
 		InitialContext ctx = getInitialContext();
 	
 		Topic result = null;
 	
 		Object topicObject = null;
 	
 		try
 		{
 			topicObject = ctx.lookup(TOPIC_JNDI_NAME);
 			result = (Topic) PortableRemoteObject.narrow(
 								topicObject,
 								Topic.class);
 		}
 		catch (NamingException ex)
 		{
 			throw new DAORuntimeException(ex);
 		}
 	
 		return result;
 	}
 	
 	/***
 	 * 	
 	 * @throws daoexamples.exception.DAORuntimeException
 	 * 
 	 */
 	static private TopicConnection getTopicConnection()
 	{
 		TopicConnectionFactory tcf = getTopicConnectionFactory();
 	
 		TopicConnection tconn = null;
 	
 		try
 		{
 			tconn = tcf.createTopicConnection();
 		}
 		catch (JMSException ex)
 		{
 			throw new DAORuntimeException(ex);
 		}
 	
 		return tconn;
 	
 	}
 	
 	/***
 	 * 	
 	 * @throws daoexamples.exception.DAORuntimeException
 	 * 
 	 */
 	static private TopicConnectionFactory getTopicConnectionFactory()
 	{
 		InitialContext ctx = getInitialContext();
 	
 		TopicConnectionFactory tcf = null;
 	
 		Object tcfObject = null;
 	
 		try
 		{
 			tcfObject = ctx.lookup(TOPIC_CF_JNDI_NAME);
 			tcf = (TopicConnectionFactory) PortableRemoteObject.narrow(
 							tcfObject,
 							TopicConnectionFactory.class);
 		}
 		catch (NamingException ex)
 		{
 			throw new DAORuntimeException(ex);
 		}
 			
 		return tcf;
 	}
 	
 	
 	/***
 	 *  
 	 * @param strText must be non-null
 	 *
 	 * @throws daoexamples.exception.DAORuntimeException
 	 *  
 	 */
 	public void publishTextMessage(final String strText)
 	{
 		if (isClosed())
 		{
 			throw new java.lang.IllegalStateException("MessagePublisher is closed");
 		}
 		
 		if (null == strText)
 		{
 			throw new NullPointerException("strText parameter");
 		}
 		
 		try
 		{
 			TextMessage textMsg = tsess.createTextMessage(strText);
 			publisher.publish(textMsg);
 		}
 		catch (JMSException ex)
 		{
 			throw new DAORuntimeException(ex);
 		}
 		
 	}  
 
 	/***
 	 *  
 	 * @return true if this object is closed
 	 * 
 	 * @see #close()
 	 * 
 	 */
 	public boolean isClosed()
 	{
 		return bIsClosed;
 	}
 		
 	/***
 	 * 
 	 *  @see #isClosed()
 	 *
 	 */
 	public void close()
 	{
 		log.info("close() called");
 		
 		if ( ! isClosed() )
 		{
 			bIsClosed = true;
 			
 			top = null;
 			
 			if (publisher != null)
 			{
 				try
 				{
 					publisher.close();
 				}
 				catch (JMSException ex)
 				{
 					log.error("exception while closing a TopicPublisher",
 							ex); 
 				}
 				finally
 				{
 					publisher = null;
 				}
 			}
 			
 			if (tsess != null)
 			{
 				try
 				{
 					tsess.close();
 				}
 				catch (JMSException ex)
 				{
 					log.error("exception while closing a TopicSession",
 							ex); 
 				}
 				finally
 				{
 					tsess = null;
 				}
 			}
 			
 			if (tconn != null)
 			{
 				try
 				{
 					tconn.close();
 				}
 				catch (JMSException ex)
 				{
 					log.error("exception while closing a TopicConnection",
 							ex); 
 				}
 				finally
 				{
 					tconn = null;
 				}
 			}
 		}
 		
 	}
 }