runtime/org.argeo.slc.support.activemq/src/main/java/org/argeo/slc/jms/JmsSlcEventListener.java

   1 package org.argeo.slc.jms;
   2
   3 import java.util.List;
   4
   5 import javax.jms.ConnectionFactory;
   6 import javax.jms.Destination;
   7
   8 import org.apache.commons.logging.Log;
   9 import org.apache.commons.logging.LogFactory;
  10 import org.argeo.slc.SlcException;
  11 import org.argeo.slc.msg.event.SlcEvent;
  12 import org.argeo.slc.msg.event.SlcEventListener;
  13 import org.argeo.slc.msg.event.SlcEventListenerDescriptor;
  14 import org.argeo.slc.msg.event.SlcEventListenerRegister;
  15 import org.springframework.jms.core.JmsTemplate;
  16 import org.springframework.jms.support.converter.MessageConverter;
  17
  18 public class JmsSlcEventListener implements SlcEventListener {
  19         private final static Log log = LogFactory.getLog(JmsSlcEventListener.class);
  20
  21         private Destination eventsDestination;
  22         private ConnectionFactory jmsConnectionFactory;
  23         private MessageConverter messageConverter;
  24
  25         public SlcEvent listen(SlcEventListenerRegister register, Long timeout) {
  26                 JmsTemplate jmsTemplate = new JmsTemplate(jmsConnectionFactory);
  27                 jmsTemplate.setMessageConverter(messageConverter);
  28                 jmsTemplate.setReceiveTimeout(timeout);
  29
  30                 List<SlcEventListenerDescriptor> descriptors = register
  31                                 .getDescriptorsCopy();
  32
  33                 if (descriptors.size() == 0) {
  34                         // No listeners, just waiting
  35                         try {
  36                                 Thread.sleep(timeout);
  37                         } catch (InterruptedException e) {
  38                                 // silent
  39                         }
  40                         return null;
  41                 } else {
  42                         String selector = createSelector(descriptors);
  43
  44                         if (log.isTraceEnabled())
  45                                 log.debug("Selector: " + selector);
  46
  47                         Object obj = jmsTemplate.receiveSelectedAndConvert(
  48                                         eventsDestination, selector);
  49
  50                         if (obj == null)
  51                                 return null;
  52                         else
  53                                 return (SlcEvent) obj;
  54                 }
  55         }
  56
  57         /** Returns null if no filter */
  58         protected String createSelector(List<SlcEventListenerDescriptor> descriptors) {
  59                 if (descriptors.size() == 0)
  60                         throw new SlcException("No listeners, cannot generate JMS selector");
  61
  62                 StringBuffer buf = new StringBuffer(256);
  63                 Boolean first = true;
  64                 for (SlcEventListenerDescriptor descriptor : descriptors) {
  65                         if (first)
  66                                 first = false;
  67                         else
  68                                 buf.append(" OR ");
  69
  70                         buf.append('(');
  71                         buf.append(SlcEvent.EVENT_TYPE).append("=").append('\'').append(
  72                                         descriptor.getEventType()).append('\'');
  73                         if (descriptor.getFilter() != null) {
  74                                 buf.append(" AND ");
  75                                 buf.append('(').append(descriptor.getFilter()).append(')');
  76                         }
  77                         buf.append(')');
  78                 }
  79                 return buf.toString();
  80         }
  81
  82         public void setEventsDestination(Destination eventsDestination) {
  83                 this.eventsDestination = eventsDestination;
  84         }
  85
  86         public void setJmsConnectionFactory(ConnectionFactory jmsConnectionFactory) {
  87                 this.jmsConnectionFactory = jmsConnectionFactory;
  88         }
  89
  90         public void setMessageConverter(MessageConverter messageConverter) {
  91                 this.messageConverter = messageConverter;
  92         }
  93
  94 }