[DFDL-WG] Action 205: whitespace in DFDL annotations

Tue Jul 9 07:09:46 EDT 2013

For discussion on today's WG call. Action 205 was raised to ensure that 
DFDL 'property types' are declared with XML Schema types that provide the 
correct whitespace handling behaviour. The XML Schema types of the various 
DFDL 'property types' are given in Part 1 of IBM's Schemas-for-DFDL.

The question boils down to whether a 'property type' should be an 
xs:string or xs:token. The former preserves whitespace, the latter 
normalizes and trims. (Note that xs:NMTOKEN is intended for attributes 
only, so should not be used for DFDL properties as they can be expressed 
in attribute or element forms.) 

My recommendation is;
- Enumeration changed from xs:string to xs:token (reason: to match XSDL 
more closely and trim leading/trailing whitespace)
- DFDL regular expression stays as xs:string (reason: regex may contain 
literal white space)
- DFDL string literal changed from xs:string to xs:token (reason: 
currently inconsistent with List of DFDL string literal)
- List of DFDL string literal stays as list of xs:token
- DFDL expression changed from xs:token to xs:string (reason: XPath may 
contain non-ignorable whitespace)

Further:
- DFDL regular expression should not trim leading/trailing whitespace
- DFDL expression should trim leading whitespace before { and trailing 
whitespace after }
- The enum of DFDL property names should be based on xs:token

The xs:unions for DFDL properties that can be two or more of the above may 
need the member ordering reviewed. Example:

        <xsd:simpleType name="BinaryFloatRepEnum_Or_DFDLExpression">
                <xsd:union>
                        <xsd:simpleType>
                                <xsd:restriction 
base="dfdl:DFDLExpression" />
                        </xsd:simpleType>
                        <xsd:simpleType>
                                <xsd:restriction 
base="dfdl:BinaryFloatRepEnum"/>
                        </xsd:simpleType>
                </xsd:union>
        </xsd:simpleType>

Usually in a union, the most restrictive member is placed first. With the 
current types, the above has xs:token followed by xs:string, in accordance 
with this practice. But the recommendation changes the types of both 
members, so that the above becomes xs:string followed by xs:token. 

Regards

Steve Hanson
Architect, IBM 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:     Suman Kalia/Toronto/IBM at IBMCA, 
Cc:     dfdl-wg at ogf.org, Mike Beckerle <mbeckerle.dfdl at gmail.com>
Date:   27/03/2013 16:38
Subject:        Re: [DFDL-WG] whitespace in DFDL annotations: right now 
regex is xs:string, expression is xs:token

Suman

Looking at the XML schema-for-schemas, and doing a test in the XSD editor 
in eclipse, XSD enumeration facets are modelled as xs:NMTOKEN and not 
xs:string, like DFDL enums. XSD is perfectly happy to strip/collapse white 
space. I think therefore that we should be doing the same for DFDL enum 
properties. I don't see any harm in this - an enum is a contiguous 
sequence of non-whitespace characters anyway, so any leading/trailing 
whitespace is harmless.

Looks like XSD pattern facet is modelled as xs:string, preserving white 
space. We should do the same for DFDL regex properties.

Regards

Steve Hanson
Architect, IBM 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:     Suman Kalia <kalia at ca.ibm.com>, 
Cc:     dfdl-wg at ogf.org, dfdl-wg-bounces at ogf.org, Mike Beckerle 
<mbeckerle.dfdl at gmail.com>
Date:   19/03/2013 17:41
Subject:        Re: [DFDL-WG] whitespace in DFDL annotations: right now 
regex is xs:string, expression is xs:token

The type called DFDLExpressionOrPatternOrNothing only makes sense for use 
in one place - the element value of an assert or discriminator.

Regards

Steve Hanson
Architect, IBM 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:   Suman Kalia <kalia at ca.ibm.com>
To:     Mike Beckerle <mbeckerle.dfdl at gmail.com>, 
Cc:     dfdl-wg at ogf.org, dfdl-wg-bounces at ogf.org
Date:   19/03/2013 17:29
Subject:        Re: [DFDL-WG] whitespace in DFDL annotations: right now 
regex is xs:string, expression is xs:token
Sent by:        dfdl-wg-bounces at ogf.org

Mike - I am not sure but my gut feeling is that it would start with the 
most restrictive one first.  i.e  If empty string    ( assuming it has 
length facet 1) -  would match Nothing ,   then xsd:token which is 
restricted form of xs:string.  I think you are going to get string with 
white spaces collpsed  ( xsd:token) if it not empty string.  You can run 
few tests to see the behavior.. 

Suman Kalia 
IBM Canada Lab 
WMB Toolkit Architect and Development Lead 
Tel: 905-413-3923 T/L 313-3923 
Email: kalia at ca.ibm.com 

For info on Message broker 
http://www.ibm.com/developerworks/websphere/zones/businessintegration/wmb.html 

From:        Mike Beckerle <mbeckerle.dfdl at gmail.com> 
To:        dfdl-wg at ogf.org, 
Date:        03/19/2013 12:43 PM 
Subject:        [DFDL-WG] whitespace in DFDL annotations: right now regex 
is xs:string, expression is xs:token 
Sent by:        dfdl-wg-bounces at ogf.org 

This came up on the call. The schemas I have for DFDL annotations have 
DFDLRegularExpression as an xs:string, and DFDLExpression as an xs:token. 
I have no clue what a union of these types behaves like. But we have a 
union called DFDLExpressionOrPatternOrNothing which is a 3-way union of 
DFDLExpression, DFDLRegularExpression, and EmptyString (which is also 
derived from xs:string but has length facet of 0 as well. 

-- 
Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | 
www.tresys.com
--
 dfdl-wg mailing list
 dfdl-wg at ogf.org
 https://www.ogf.org/mailman/listinfo/dfdl-wg --
  dfdl-wg mailing list
  dfdl-wg at ogf.org
  https://www.ogf.org/mailman/listinfo/dfdl-wg

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/20130709/5d408935/attachment.html>