How to set up the maximum number of messages on a queue programmatically

Question

Hi,
I am using IMQ 3.5 to implement a message layer for one of my projects. I created a "Job Status Queue", which receives job status report from a java application every minute. But I just want to keep the most current status report instead of all the job running history. How can I restrict the maximum number of messages to 1 programmatically?
Any suggestion or help will be appreciated.
Xiaoyun Tang

Answer 1

You can't limit the destination size programmatically, but you can do it administratively and associate a behavior to occur when the limit is reached. In your case it sounds like you want a queue, 1 message deep, and to discard the oldest message when the queue is full. When you create the physical queue on the broker you can specify these attributes (you can also update them on an existing queue). For example:
imqcmd create dst -t q -n StatusQ -o maxNumMsgs=1 -o limitBehavior=REMOVE_OLDESTFor more information see Chapter 6 of the Message Queue Administration Guide. In particular the "Managing Destinations" section:
http://docs.sun.com/app/docs/coll/MessageQueue_35_SP1
Joe