[DFDL-WG] How to specify type/subtype combos?

Fri Jun 21 10:39:04 EDT 2013

>  I wouldn't be surprised if, with sufficient ingenuity, it was possible to make DFDL do what you need in this particular case

Mike Bekerle, what’s your current job title?  Something like “Senior Software Developer” maybe?  Time to upgrade.  Your new title is “Possessor of  Sufficient Ingenuity,” as you came up with this answer:

            <xsd:sequence>
               <xsd:annotation>
                   <xsd:appinfo source="http://www.ogf.org/dfdl/dfdl-1.0/">
                       <dfdl:assert message="The type and subtype must be a matching pair.">
                           {

                           if      ((Type/text() eq 'application')  and (Subtype/text() eq 'pdf')) then true()
                           …
                           else if ((Type/text() eq 'text')         and (Subtype/text() eq 'plain')) then true()
                           else false()
                           }
                       </dfdl:assert>
                   </xsd:appinfo>
               </xsd:annotation>
            </xsd:sequence>

> DFDL is based on XML Schema, so its validation facilities don't include cross-field validation.

Partially true.  XML Schema 1.1 supports cross-field validation.  The first working draft came out 9 years ago, and it’s been stable for 4 or 5 years.  Maybe DFDL should be upgraded to 1.1?

From: dfdl-wg-bounces at ogf.org [mailto:dfdl-wg-bounces at ogf.org] On Behalf Of Tim Kimber
Sent: Thursday, June 20, 2013 4:10 PM
To: dfdl-wg at ogf.org
Subject: Re: [DFDL-WG] How to specify type/subtype combos?

Good question. I call this type of validation 'cross-field validation' because ( unlike XML Schema validation ) it involves the value or count of more than one field. It's quite common in industry messaging standards.

The general answer is as follows: DFDL is based on XML Schema, so its validation facilities don't include cross-field validation. However, by using DFDL to convert to DOM/XML you can bring your non-XML data within reach of whole lot of tools and technologies that were originally designed for XML. I'm thinking about XPath, XQuery, Schematron, RELAX-NG etc. This should not be viewed as a shortcoming of the DFDL language - DFDL is for describing the format, not the higher-level validation rules.

Having said that, I wouldn't be surprised if, with sufficient ingenuity, it was possible to make DFDL do what you need in this particular case. Let's see if any suggestions are forthcoming...

regards,

Tim Kimber, DFDL Team,
Hursley, UK
Internet:  kimbert at uk.ibm.com<mailto:kimbert at uk.ibm.com>
Tel. 01962-816742
Internal tel. 37246742

From:        "Garriss Jr., James P." <jgarriss at mitre.org<mailto:jgarriss at mitre.org>>
To:        "dfdl-wg at ogf.org<mailto:dfdl-wg at ogf.org>" <dfdl-wg at ogf.org<mailto:dfdl-wg at ogf.org>>,
Date:        20/06/2013 16:34
Subject:        [DFDL-WG] How to specify type/subtype combos?
Sent by:        dfdl-wg-bounces at ogf.org<mailto:dfdl-wg-bounces at ogf.org>
________________________________

Content types come in pairs.  So while the type can be “text” and the subtype can be “pdf”, the complete content type cannot be “text/pdf”.  It can, however, be “text/html” or “application/pdf”.

So in my DFDL it’s not sufficient to specify enumerated lists for types and subtypes (as I have done below), I must also specify which types are allowed to go with which subtypes.

How would I do that, given this complexType?  TIA!

    <xsd:complexType name="MimeTypeType">
       <xsd:sequence dfdl:separator="/">
           <xsd:element name="Type" dfdl:initiator="">
               <xsd:annotation>
                   <xsd:appinfo source="http://www.ogf.org/dfdl/dfdl-1.0/">
                       <dfdl:assert test="{ dfdl:checkConstraints(.) }" message="The type must match one of the values on the enumerated list."/>
                   </xsd:appinfo>
               </xsd:annotation>
               <xsd:simpleType>
                   <xsd:restriction base="xsd:string">
                       <xsd:pattern
                           value="([a|A][p|P][p|P][l|L][i|I][c|C][a|A][t|T][i|I][o|O][n|N])|
                           ([m|M][u|U][l|L][t|T][i|I][p|P][a|A][r|R][t|T])|
                           ([m|M][e|E][s|S][s|S][a|A][g|G][e|E])|
                           ([t|T][e|E][x|X][t|T])"
                       />
                   </xsd:restriction>
               </xsd:simpleType>
           </xsd:element>
           <xsd:element name="Subtype" dfdl:terminator="">
               <xsd:annotation>
                   <xsd:appinfo source="http://www.ogf.org/dfdl/dfdl-1.0/">
                       <dfdl:assert test="{ dfdl:checkConstraints(.) }" message="The subtype must match one of the values on the enumerated list."/>
                   </xsd:appinfo>
               </xsd:annotation>
               <xsd:simpleType>
                   <xsd:restriction base="xsd:string">
                       <xsd:pattern
                           value="([p|P][d|D][f|F])|
                           ([a|A][l|L][t|T][e|E][r|R][n|N][a|A][t|T][i|I][v|V][e|E])|
                           ([m|M][i|I][x|X][e|E][d|D])|
                           ([r|R][f|F][c|C]822)|
                           ([p|P][l|L][a|A][i|I][n|N])|
                           ([h|H][t|T][m|M][l|L])"
                       />
                   </xsd:restriction>
               </xsd:simpleType>
           </xsd:element>
       </xsd:sequence>
   </xsd:complexType>

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