[xml] DFDL schemas parsing



I’m currently looking at the DFDL (http://www.ogf.org/dfdl/). DFDL is for “Data Format Description Language” and aims to provide a standardized way of describing data formats relying on XML schemas formalism. I was wondering if libxml2 would be able to parse DFDL schemas as it uses a subset of XML schemas. I know that the support of XML schemas in libxml2 is partial so below is the list of features used by DFDL mentioned in the specification (http://www.ogf.org/documents/GFD.174.pdf, chapter 5.1). I’m not sure if that list is meaningful for you, however, I would like to know if there could be any issue regarding the support of those features in libxml2?


DFDL Schemas consist of:

•  Standard XSDL namespace management

•  Standard XSDL import and management for multiple file schemas

•  Local element declarations with dimensionality via xs:maxOccurs and xs:minOccurs.

•  Global element declarations

•  ComplexType definitions with empty or element-only content

•  DFDL appinfo annotations describing the data format

•  These simple types: string, float, double, decimal, integer, long, int, short, byte,

nonNegativeInteger, unsignedLong, unsignedInt, unsignedShort, unsignedByte, boolean,

date, time, dateTime, hexBinary

•  These facets: minLength, maxLength, minInclusive, maxInclusive, minExclusive,

maxExclusive, totalDigits, fractionDigits, enumeration, pattern (for xs:string type only)

•  Fixed values

•  Default values

•  'sequence' model groups (without xs:minOccurs and xs:maxOccurs)

•  'choice' model groups (without xs:minOccurs and xs:maxOccurs)

•  Simple type derivations derived by restriction from the allowed built-in types

•  Reusable Groups: named model group definitions can only contain one model group

•  Element references with dimensionality via xs:maxOccurs and xs:minOccurs.

•  Group references without dimensionality

•  xs:nillable="true" only on elements of simple type.

•  Appinfo annotations for sources other than DFDL are permitted and ignored

•  Unions; the memberTypes must be derived from the same simple type. DFDL

annotations are not permitted on union members. 3

•  XML Entities



Thank you in advance for your help!


Best regards,


Matthieu Hazon


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