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RE: EXI WG's inquiry about ISSUE-2050

From: Takuki Kamiya <tkamiya@us.fujitsu.com>
Date: Tue, 15 May 2012 16:44:57 -0700
To: Robin Berjon <robin@berjon.com>
CC: Chris Lilley <chris@w3.org>, "www-svg@w3.org" <www-svg@w3.org>, "member-exi-wg@w3.org" <member-exi-wg@w3.org>
Message-ID: <23204FACB677D84EBD57175AB7B5A71C01176D1613F6@FMSAMAIL.fmsa.local>
Hi Robin and all,

The rule of thumb in the better design of schemas for EXI is 
that the more rigorous the schema is the more compactness 
you can achieve out of EXI.

Also, I am interested in knowing the aspects of the
relaxNG schema SVG is exercising that are not supported 
by XSD 1.0, and the rationale that led SVG 1.x to depend 
on them. This is to see if it is totally out of whack to
apply XML Schema, or is manageable.



-----Original Message-----
From: Robin Berjon [mailto:robin@berjon.com] 
Sent: Thursday, May 10, 2012 2:24 AM
To: Takuki Kamiya
Cc: Chris Lilley; www-svg@w3.org; member-exi-wg@w3.org
Subject: Re: EXI WG's inquiry about ISSUE-2050

Hi Takuki,

On May 9, 2012, at 12:09 , Takuki Kamiya wrote:
> Once such a shim API is in place for verbose XML path syntax, EXI will fit
> squarely to serve as an content-coding for SVG file exchanges.

It may prove useful if the EXI WG were to suggest a specific syntax for this, or at least guidelines as to what would achieve the best compression - which the SVG WG would likely balance against ease-of-authoring needs.

Note that it should be easy to prototype this functionality using JS to show that it is usable. It's been done before (but I can't seem to find the code - it's old :).

> From EXI WG's point of view, we would like to make EXI work to its fullest 
> to best serve SVG documents. One significant ingredient to achieve that is the
> use of XML Schemas. EXI uses XML Schemas not for validation, but for 
> informing the processors of the most likely structure/datatypes of the
> documents. We are aware that SVG is using Relax NG for defining its syntax.
> We would like to explore the idea of having a parallel normative XML Schema 
> that is not for defining SVG syntax but for informing EXI processors of what 
> it can expect more likely than others gramatically. We would like to have this
> discussed together with SVG WG. Is this something that we can work together
> on among other aspects?

Conversion from RNG to XSD ought to be possible in this case, but my concern would be the work involved in maintaining the two. I wonder if it would be possible to generate both based on some simplified syntax. A number of SVG's content models cannot be adequately captured by XSD, but I guess that those can for the most part be automatically simplified.

> Since the EXI WG is going to meet during TPAC this year, we thought it a 
> great chance for the two WGs to get acquiainted and discuss the issue
> face-to-face, depending on the schedule of the two WGs. 

If there's a chance that I could be looped into that meeting, I'd love to be there (crazy TPAC schedule permitting).

Robin Berjon - http://berjon.com/ - @robinberjon
Received on Tuesday, 15 May 2012 23:46:41 UTC

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