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From Thomas Dudziak <tom...@gmail.com>
Subject Re: RFC: Multi-Level Timeouts for Default Cache
Date Mon, 27 Jun 2005 09:00:35 GMT
> For me the logical place to put the time-to-live is at the ClassDescriptor
> level, since I think this info statically belongs to the class definition.
> I do not see the use-case where cache TTL for a specific class should be
> different between different jcd:s?

Imagine a larger-scale web application (load-balanced etc,) that is
meant to run on a DB2 database. For development and unit test purposes
the developers might probably want to use not a fully-fledged DB2 but
rather a local (embedded) Derby. But with the cache-settings for the
big database (which might even use a different cache altogether) this
will likely lead to problems.
> I think it's enough with the current global cache-config TTL plus the
> possibility to override it on the class-descriptor level.

I was wondering whether a more configurable strategy will help here.
For instance, we could allow the user to define the classification
himself, e.g.

<class-descriptor ... longevity="short">
<class-descriptor ... longevity="really-short">

which can them be mapped in the cache-descriptor to timeouts (and
other info where necessary):

<object-cache ...>
  <cache-class name="really-short" timeout="100"/>
  <cache-class name="short" timeout="1000"/>

This would allow for pluggable caches (e.g. a cache for a local
database might define the same timeouts for these thus making them
equivalent), and the developers can specify their intention regarding
the longevity of the classes.


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