JMS Queue monitoring

Question

Hi everyone,
is there any way to monitor a jms queue with its contained messages ? i'm talking about a tool like the jmx console in jboss - the JMS Adapter and JMS Notification in the Visual Admin only provide some properties.
Any suggestions ?

Answer 1

Hi,
In short what you want (sending email in case message has stayed too long time in the queue), is NOT possible directly. That's not a standard feature by the JMS spec.   
What is possible is the is so-called dead messages, once the acknowledgment fails the predefined number of times then the messages will be redirected to a special queue. From there the messages can be exported by telnet.
Check SAP note 777930 for more info. Btw, it might be a good idea to get familiar with that note, otherwise if the external server let's say always throws an exception while processing the message, it will be moved to this special queue and unless someone issues the appropriate telnet commands, nobody will understand about this.
However if you disable this  feature, that will mean that the message will be delivered endlessly, causing CPU load. Not nice if you have doubts in your external listeners.                                                                               
Now about the queue monitoring :
You could create manually a periodic task (EJB timers in J2EE 1.4 which is covered in the prerelease of the next server version, or if you are using Netweaver 04s or 04s than perhaps java.util.Timer) that will periodically open a JMS browser, check the  messages in the queue, if they have stayed too long time (>100 seconds for example ?) or if the queue is too big (>100 messages) you can send manually the email alert that something has went wrong. By usage of the JAVA API that should be simple
Another thing you can do is that inside your external listeners and the onMessage method, you could check manually the number of times the message is redelivered, if it is above some threshold (i.e . if it is 3, that means the SAP server has delivered the message 3 times , since the listener have rejected it 2 times already),then you can send the email via the standard java API. The delivery count can be retrieved by using the standard optional property JMSXDeliveryCount from the message.                                                      
HTH
Peter