Re: Enterprise using WO

At 10:46 AM +0800 5/22/05, Ashley Aitken wrote:
>On 22/05/2005, at 10:38 AM, Mark F. Murphy wrote:
>>I'm very skeptical of network based notifications.  I've just 
>>always used the pattern that if I need fresh data from the 
>>database, I should go back to the database (the original store) to 
>>get fresh data anyway.  The database can scale and is built to do 
>>so.
>
>Yes, but how do you know when to go back to the database?

It doesn't matter.  You do it all the time.

>That's the whole point of network-based notifications.  Otherwise 
>you would have to check with the database every time you use the 
>data (to see if it has changed).  No caching and no performance.

With notification based approaches, you also get all kinds of 
notifications for data you don't need updated.  Then you have to 
wonder about the scale of your notification mechanism.

The database is a better place to scale than to try to send 
notifications on changes to all the caches in a cluster.

There's some professional cluster cache mechanisms that might be 
worthwhile... but they give a lot of different approach options.

http://www.tangosol.com/coherence.jsp
http://www.jboss.org/products/jbosscache

mark

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  Mark F. Murphy, Director Software Development   <mailto:[email protected]>
  Tyrell Software Corp                            <http://www.tyrell.com>
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