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

20 Jun 2013

      You could use an assert on the sequence that tested for the allowed 
combinations?  Such an assert is evaluated at the end of the sequence. If 
you get that far then both the Type and Subtype must have passed their 
individual asserts. Use fn:upper-case() to handle mixed case.  Note that 
you can't reuse the information in the facets in the assert's expression 
though.

Strictly speaking, this sort of cross-field 'complex' validation is not 
something DFDL was designed to do. The WG has considered this a post-parse 
validation step, the sort of thing that folk use Schematron or similar 
tools to do.  Although asserts are designed as a parsing aid, they can be 
used to do some limited amount of complex validation - and I think this is 
an example where it would work ok.

Let us know how you get on.

Regards

Steve Hanson
Architect, IBM Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh@uk.ibm.com
tel:+44-1962-815848

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