Re: Caching grammars

That does seem to be the way it works. I dug into the source more after my
initial post. It seems that the grammar pool in the Schema is used to
initialize a second grammar pool owned by the Validator. This second
grammar pool lives only as long as the validator.

I haven't gotten back into that part of my code in a week or so, but I
believe I can ultimately get my grammars that are dynamically loaded via
the LSResourceResolver by reusing my Validator. Of course, the Validator is
not thread-safe, so I will probably use a ThreadLocal<Validator>.
(Synchronizing a single validator is probably not acceptable in my
environment.)

Of course, that means I will end up with a grammar cache in each thread in
my thread pool. So my next step is to figure out if the grammars are thread
safe. If they are, perhaps I can figure out a way to share a single
instance of a thread safe grammar cache between validators.


On Sun, Jan 20, 2013 at 10:23 AM, Michael Glavassevich
<[email protected]>wrote:

> The JAXP Schema created through SchemaFactory.newSchema() caches grammars
> (through SoftReferences [1]) by their schema location. It's been quite
> awhile since I've looked at how this works, but it wouldn't surprise me if
> Xerces calls your LSResourceResolver each time you validate in order to
> give your application an opportunity to redirect the schema location and
> then use the value returned from the LSResourceResolver to look up the
> cached grammar.
>
> Thanks.
>
> [1]
>
> http://svn.apache.org/viewvc/xerces/java/trunk/src/org/apache/xerces/jaxp/validation/SoftReferenceGrammarPool.java?annotate=699892
>
> Michael Glavassevich
> XML Technologies and WAS Development
> IBM Toronto Lab
> E-mail: [email protected]
> E-mail: [email protected]
>
> Robert Huffman <[email protected]> wrote on 12/01/2013 05:04:17 PM:
>
> > I must parse documents that may use a large number of fairly large
> > XSDs. However, the large majority of documents will not use most of
> > those XSDs. Therefore, I would like to use a custom
> > LSResourceResolver to resolve the target namespaces to local
> > resources during parsing rather than building a Schema object that
> > has all the grammars loaded up front.
> >
> > Unfortunately, as nearly as I can tell, grammars loaded through the
> > use of a LSResourceResolver are never cached in the grammar pool. Is
> > that correct? Is there some nuance I'm missing?
>
>
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