Thanks Jonathan.  That makes sense to me but it doesn't account for the rise
in RSS/Atom systems when a) a messaging system is more reliable and b) a SQL
source can do the same thing internally.   It seems to beg the question of
why publish/subscribe models (eg. RSS/Atom) are in vogue.   I can continue
what I am doing now which is a mixed screen with RSSReader for feeds and
local gridviews with SQL sources for the internal feeds.  I had hoped to
simplify but horses for courses.  

Given the schedule crunch, it isn't possible to use the systems you mention
but that doesn't preclude them in the future.   We've dropped one expensive
proprietary mapping system in favor of Open Layers and that is working out
quite well; so now customers have to be convinced that they can afford to
not specify the proprietary source as a requirement to win their business.
It takes successful applications to do make that recognition widespread and
we both understand the chicken-and-egg of that.  

I'm sitting in a former Red Hat building.  Not sure where they moved to.
I'll have to ask Steve Conklin when I see him next.  Too bad they didn't
leave the pool table.

len


From: Jonathan Robie [mailto:jonathan.robie@r...] 
 
Hi Len,

Here are some reasons that a messaging system might be better for this 
kind of application:

1. Updates are made precisely when something has changed at the source. 
This eliminates the need for clients to poll just in case something has 
changed, which accounts for a lot of unnecessary polling.

2. Guaranteed delivery is supported.

3. Higher performance network protocols can be used.

I think the existence of open source, high performance, reliable 
messaging systems has the potential to significantly change the way 
people write a lot of systems, including a lot of XML-based systems. 
This is one of the reasons I'm at Red Hat now.

Jonathan
 
This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the sender. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail.