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From Ed Staub <>
Subject RE: cache and performance
Date Wed, 05 Jul 2000 13:45:16 GMT
Stefano wrote:
>> What are the caching strategy for the XML,XSLT,XSP,SQL parts in Cocoon1
>>vs. Cocoon2?!

>Exactly the same: we provide the caching architecture, you write your
>caching strategy.

It's often expensive to check whether a cached resource has changed.  In
particular, accessing a database to see if change has occurred may be as
expensive as retrieving the original data.

In many (perhaps most) uses of resource inclusion, it's ok to use slightly
stale information in a production environment.

It might be useful to provide resource-consuming documents with a uniform
way of specifying just how "fresh" the consumed resource must be.  This
would eliminate unnecessary checking and cache reloads.  

In cases where the consumer of the resource is also a cached resource, the
effect COULD be recursive; the consumer would potentially make more
effective use of caching also.  In order for this to be effective, the
processor of the consuming document would require a way to quickly traverse
the set of consumed resources, without processing the entire document. There
may be some significant design issues here.

For example, an XInclude element might include a new attribute:
	<xinclude:include href="something.xml" cache-expire="P10M"/>
to say that the cache for this inclusion need only be checked every ten
minutes. (The "P10M" is in ISO 8601 syntax.) 

If folks here in CocoonLand see any merit in this notion, I'll also drop a
note on the W3C XInclude group.

-Ed Staub

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