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[LC-2187] RE: Comment for EXI Draft - Grammar learning

From: Taki Kamiya <tkamiya@us.fujitsu.com>
Date: Wed, 11 Feb 2009 11:40:21 -0800
To: "'TAMIYA Keisuke'" <tamiya.keisuke@canon.co.jp>, <public-exi-comments@w3.org>
Cc: <youenn.fablet@crf.canon.fr>, <fujisawa.jun@canon.co.jp>
Message-ID: <10E8E71770A2429F95CED8C433D85064@homunculus>

Hi Tamiya-san,

We understand the concern you have raised over the issue grammar
learning behaviour may pose on the size of memory EXI processor
consumes and requires.

While acknowledging it is a potential issue, we had stopped short of
adding a mechanism to restrain grammar learning at the time we dicussed
the feature a while back, based on implementation report of the feature
shared by the WG memebers, which suggested otherwise that the issue did
not surface in real deployments.

One of the traits that documents for use in exchange in general is that
grammars are learned a lot up front at a pace close to linear rate, and
the learning becomes less and less frequent, eventually saturating to a
convergence. This observation helps explain why the issue is not very
likely to emerge in practice.

Based on these observation and analysis, as well as the consideration of
the cost that would otherwise be incurred if a restraining mechanism was
introduced both in terms of compactness and runtime efficiency, we stay
cautious and may require further arguments involving specific use cases
before we consider a way to alleviate the potential issue.

Thanks!

-taki


-----Original Message-----
From: public-exi-comments-request@w3.org [mailto:public-exi-comments-request@w3.org] On Behalf Of TAMIYA Keisuke
Sent: Thursday, November 06, 2008 9:19 PM
To: public-exi-comments@w3.org
Cc: youenn.fablet@crf.canon.fr; fujisawa.jun@canon.co.jp
Subject: Comment for EXI Draft - Grammar learning


Dear W3C EXI WG members,

I have a comment for this draft specification.

EXI has a mechanism of the grammer leaning (ref. Section 8).
So, an EXI parser use large memory to keep grammar data, if the XML data
has many kinds of node (ex. element).
For small devices, this is a serious problem.
I think the limitation mechanism of the grammar learning is needed in
the specification (ex. MAX number of the kind of event code).

Regards,
Keisuke Tamiya (tamiya.keisuke@canon.co.jp)
Received on Wednesday, 11 February 2009 19:41:45 UTC

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