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From "James Strachan" <james.strac...@gmail.com>
Subject Re: Input queue and output queue grouping and sequences question
Date Wed, 11 Apr 2007 18:30:17 GMT
On 4/10/07, tnine <todd.nine@gmail.com> wrote:
>
> Hi All,
>   I'll be writing a process that uses parallel grid processing to process
> message groups.  I'm new to Active MQ and could use some help in finding
> documentation or examples.
>
> I'll be running in the following environment
> Java 1.6
> JBoss 4
> Active MQ 4.1.1
> RHEL4
>
> I know I will be performing the following operations.
>
> 1. Create a text message with the following format.  [company-name]-[ISO
> Date]
> 2. Push all text messages into this group
> 3. When I'm done producing all of the messages, I'll perform the
> message.setIntProperty("JMSXGroupSeq", 0); to close the group.
>
> I have have the following questions.
>
> Producer/Consumer
>
> 1. Is it possible to insert multiple messages into the queue in a single XA
> transaction?

Yes - whether using JMS or XA transactions, you can send or receive
multiple messages; its up to you when you do the commit


>  If so is there an example?  Since the input is a large flat
> file, I want either all messages to be inserted or none.

How large is the file?


> 2. Is there a way for me to detect on the MDB side when the last message is
> sent? Can I simply perform the message.getIntProperty("JMSXGroupSeq") and
> search for the value 0 to find the last message?

Sure. Or just add your own header to indicate the last message if you prefer


> 3. I have 2 queues, one input queue, and one output queue.  Both queues need
> to be processed in the exact same order.  As the MDB reads from the input
> queue, can I put the same JMSXGroupSeq number into the output queue message
> and still have the same ordering semantics without screwing up the Group
> processing in Active MQ?

The 2 queues are processed separately by different consumer groups;
but sure order would be guarrenteed if you use the same JMSGroupID


> Monitoring
>
> I want to write a simple webapp that shows the percentage of message in the
> queues.  Is it possible to read the groups, and for each group show the
> messages on the queue?

Not efficiently; you could write your own Interceptor to do just that

http://activemq.apache.org/interceptors.html

but you could inefficiently do it by just browsing the queue via the
QueueBrowser on JMS to figure out the numbers etc

-- 

James
-------
http://radio.weblogs.com/0112098/

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