[DFDL-WG] Issue 168 - Re: Fw: Escape scheme properties that can be expressions
Steve Hanson
smh at uk.ibm.com
Thu Apr 5 13:13:03 EDT 2012
Agreed on DFDL WG call on 5th April 2012 to take an errata to improve the
wording as below, but not to disallow relative exprs in defineFormat or
defineEscapeScheme, as it prejudges usage.
Regards
Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848
From: Steve Hanson/UK/IBM
To: Mike Beckerle <mbeckerle.dfdl at gmail.com>
Cc: dfdl-wg at ogf.org
Date: 05/04/2012 12:40
Subject: Re: Issue 168 - Re: [DFDL-WG] Fw: Escape scheme properties
that can be expressions
Mike
I think the wording in 6.3.2 applies specifically to the anonymous
dfdl:format. I don't think it was intended to apply to dfdl:format inside
dfdl:defineFormat nor to dfdl:escapeScheme inside dfdl:defineEscapeScheme,
presumably due to the reasons we discussed on last week's call - namely
that by using dfdl:ref they can be applied directly to a specific object.
Of course, dfdl:ref can be used on the anonymous dfdl:format too, So the
6.3.2 words should have said:
"In the dfd:format annotation on the xs:schema, a DFDL property either
declared locally or obtained via dfdl:ref and which uses a DFDL
expressions to provide its value MAY NOT contain relative paths".
So I think we still need to decide on dfdl:format inside dfdl:defineFormat
nor to dfdl:escapeScheme inside dfdl:defineEscapeScheme.
Regards
Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848
From: Mike Beckerle <mbeckerle.dfdl at gmail.com>
To: Steve Hanson/UK/IBM at IBMGB
Cc: dfdl-wg at ogf.org
Date: 03/04/2012 15:45
Subject: Issue 168 - Re: [DFDL-WG] Fw: Escape scheme properties
that can be expressions
In the absence of a compelling reason to allow relative paths here, I
think the conservative choice is to retain this rule from 6.3.2.
However, I did think about this and my evaluation on this topic is that
allowing relative paths makes things just a little more complicated
analytically to insure one gets good performance, but as DFDL does not
allow recursive types, it is a relatively simple analysis to convert any
relative path use in DFDL into absolute paths. So I am not worried about
there being performance impact.
...mikeb
On Mon, Apr 2, 2012 at 7:30 AM, Steve Hanson <smh at uk.ibm.com> wrote:
We took action 168 on the last call to discuss the issue of relative paths
in expressions for properties in global formats.
168
Relative path expressions in global annotations (Mike)
28/03: Mike to check that allowing relative paths does not cause
performance problems for an implementation.
05/04:
Just seen this in section 6.3.2. of the spec: "DFDL expressions that are
used to provide the value of DFDL properties in the dfd:format annotation
on the xs:schema MAY NOT contain relative paths".
Regards
Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848
----- Forwarded by Steve Hanson/UK/IBM on 02/04/2012 12:28 -----
From: Steve Hanson/UK/IBM
To: dfdl-wg at ogf.org
Date: 14/03/2012 16:09
Subject: Escape scheme properties that can be expressions
The spec allows the escapeCharacter and escapeEscapeCharacter of DFDL
escapeScheme to be expressions, in case the characters are supplied
dynamically in the data stream.
However given that escape schemes are defined globally, should these
properties be permitted to take relative paths in the expression?
Today the spec implicitly allows this, meaning an implementation can not
entirely validate an escapeScheme annotation up front, but must validate
escapeCharacter and escapeEscapeCharacter at each point of use.
I'm not sure it makes much sense for the path to be anything than
absolute.
Regards
Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
--
dfdl-wg mailing list
dfdl-wg at ogf.org
https://www.ogf.org/mailman/listinfo/dfdl-wg
--
Mike Beckerle | OGF DFDL WG Co-Chair
Tel: 781-330-0412
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number
741598.
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.ogf.org/pipermail/dfdl-wg/attachments/20120405/f578b8dd/attachment-0001.html>
More information about the dfdl-wg
mailing list