incubator-general mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From robert.j.gr...@jpmorgan.com
Subject Re: Dynamic message selectors and message scheduling
Date Sun, 13 Aug 2006 19:33:09 GMT
One option in AMQP would be to write a custom exchange to handle the
concept of delivery at a scheduled time. Exchanges are effectively an
extension point in the protocol so that you can customise delivery
algorithms.

The Glasgow broker currently doesn't have a well defined API to allow the
average end user to plug in new exchanges but this is definitely something
I think we will want to get to. Getting use cases such as yours definitely
helps us understand what type of thing users might want to be able to do in
an exchange.

Robert


                                                                                         
                                             
                      "Noel J. Bergman"                                                  
                                             
                      <noel@devtech.com        To:       <general@incubator.apache.org>
                                               
                      >                        cc:                                    
                                                
                                               Subject:  Dynamic message selectors and message
scheduling                              
                      13/08/2006 20:14                                                   
                                             
                      Please respond to                                                  
                                             
                      general                                                            
                                             
                                                                                         
                                             




In the thread titled "RE: [Proposal] Blaze", James Strachan wrote:

>  Noel J. Bergman <noel@devtech.com> wrote:
> > Totally unrelated ... JMS has the ability to create a message filter,
but
> > one of the limitations is that the filter is applied when the receiver
is
> > created, rather than when a get operation is executed.  This makes
sense
for
> > the push receiver case, but is limiting for the pull receiver case.
Does
> > AMQP have anything to say about this aspect of messaging, or does it
stay
> > strictly in the messaging provider space, and away from the client API?

> Could you explain a little more about your use case - it sounds
> interesting :). Do you only want to fetch a single message with a
> different filter per message, or just change the fliter from time to
> time. If its the latter then creating JMS consumers is pretty cheap &
> you can use any JMS to do that. Though the former, there's no 'give me
> a message using filter X' type operation.

Sorry for the delayed response.  Been busy on many fronts.

My particular use case involves selecting the next message in the
destination whose scheduled time is less than or equal to now.  If there
were a "now" operation available in the query language, I wouldn't have to
change the selector, but the expression would still have to be constantly
reevaluated.  And in that case, I'd want both pull and push behavior to be
supported.

One alternative is writing a broker to handle scheduling, which means
posting all messages intended to be rescheduled to the broker, which would
post them back when the schedule time occurs, thus handling scheduling in a
similar manner to how MQ handles subscriptions.

             --- Noel



---------------------------------------------------------------------
To unsubscribe, e-mail: general-unsubscribe@incubator.apache.org
For additional commands, e-mail: general-help@incubator.apache.org





This communication is for informational purposes only. It is not intended as an offer or solicitation
for the purchase or sale of any financial instrument or as an official confirmation of any
transaction. All market prices, data and other information are not warranted as to completeness
or accuracy and are subject to change without notice. Any comments or statements made herein
do not necessarily reflect those of JPMorgan Chase & Co., its subsidiaries and affiliates.

This transmission may contain information that is privileged, confidential, legally privileged,
and/or exempt from disclosure under applicable law. If you are not the intended recipient,
you are hereby notified that any disclosure, copying, distribution, or use of the information
contained herein (including any reliance thereon) is STRICTLY PROHIBITED. Although this transmission
and any attachments are believed to be free of any virus or other defect that might affect
any computer system into which it is received and opened, it is the responsibility of the
recipient to ensure that it is virus free and no responsibility is accepted by JPMorgan Chase
& Co., its subsidiaries and affiliates, as applicable, for any loss or damage arising
in any way from its use. If you received this transmission in error, please immediately contact
the sender and destroy the material in its entirety, whether in electronic or hard copy format.
Thank you.
 

---------------------------------------------------------------------
To unsubscribe, e-mail: general-unsubscribe@incubator.apache.org
For additional commands, e-mail: general-help@incubator.apache.org


Mime
View raw message