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Subject: RE: [ubl-dev] SBS and Restricted Data Types
<Quote>
but the in-progress customisation methodology
</Quote>
Can anyone point me to the latest version of this customisation
methodology please? That is something that might be very helpful. I
searched both within the TC Documents page and Google, and found only a
few references without URLs (sorry if I missed a URL reference).
Thanks,
Joe
Joseph Chiusano
Associate
Booz Allen Hamilton
700 13th St. NW, Suite 1100
Washington, DC 20005
O: 202-508-6514
C: 202-251-0731
Visit us online@ http://www.boozallen.com
-----Original Message-----
From: stephen.green@systml.co.uk [mailto:stephen.green@systml.co.uk]
Sent: Thursday, May 04, 2006 11:40 AM
To: ubl-dev@lists.oasis-open.org
Subject: RE: [ubl-dev] SBS and Restricted Data Types
Joe,
Hi. Briefly, the use of XSD (or maybe better still, RelaxNG) is fine for
creating a schema to describe the layout of the subset definition file
(this is getting tricky to say - definitions of definitions, etc). We
can use XSD to adjust the definition file * layout * such as adding new
attributes to cater for different types of subset.
This is what I meant by 'methodology extension'.
However, I have personally found major weaknesses in XSD (W3C Schema)
which fall short of some of the requirements of UBL and other folk have
identified such problems too.
Three weaknesses seem to be
1. limits of how derivation works, in particular 2. enumerations cannot
be derived 3. elements and attributes are either valid or invalid with
no further
distinctions allowed
I think these limitations have forced extra work on the UBL TC, such as
for versioning, customisation, codelists and subsets.
I'd better not go into detail here (short of advertising UBL courses :-)
but the in-progress customisation methodology, codelist methodology and
just finished subset methodology, together with improvements in the XML
design of the UBL 2 schemas these things do seem to answer the main
aspects of these problems, even if not perfectly. They required us to go
beyond what W3C Schema allowed and into Schematron, XPaths, custom XML
definitions (such as genericode) and maybe NVDL.
We put out long, in depth enquiries and investigations such as on
XML-dev and the like to ascertain that W3C Schema wasn't sufficient to
do all this with and still had to use the above.
All the best
Steve
Quoting Chiusano Joseph <chiusano_joseph@bah.com>:
> Please see comment regarding the following, marked with [JMC]:
>
>> (1) Regarding the approach proposed just below: The XPath.xml subset
>> definition files do not specific the data type for an element. Given
>> that the set of valid constraining facets for an XSD simple data type
>> varies according to the data type (e.g. for a data type of xsd:date,
>> a
>
>> constraining facet of "maxExclusive" is valid, but that same
>> constraining facet is not valid for xsd:string), it would therefore
>> not be possible to validate that a given constraining facet (what we
>> call a "restriction-pattern" below) in an XPath.xml subset definition
>> file is valid given the element's data type.
>
> I guess these are just the things we'd need to consider for a
> methodology extension to cover implementation-specific, more granular,
> tighter subsets and a schema extension for such definitions.
>
>>
>> Therefore, during validation one would need to refer back to the full
>> schema for the data type - unless the data type was also included in
>> the XPath.xml subset definition file. Is this correct?
>>
>
> Yes, one has to provide a developer (or auto-generation tool) with
> both subset definition and the parent schemas. My guess is (not having
> examined it in detail recently) one has to do this anyway, unless
> there is reason to
> combine all the schema information into the subset definition :-(
>
> [JMC] Comment on both responses above, and speaking only for W3C
Schema:
> Given that W3C Schema already has features such as extension and
> redefine that are supported by many tools today, at what point does
> the "methodology extension" referred to above begin to re-invent what
> W3C Schema already allows? There is also the mention of "more
> granular, tighter subsets and a schema extension for such definitions"
> - knowing the issues folks have with W3C Schema, what is so lacking
> about W3C Schema (a ratified standard for 5 years now) that warrants
> potentially reinventing the wheel here? (continued below - breaking
> for
> readability:)
>
> [JMC] If all one really needs to do is restrict data types using
> constraining facets, and add additional elements not currently
> supported, this can be done with W3C Schema. What am I missing here?
> What is the benefit of using SBS over such an approach? Please educate
> me, as I want to learn.:) (I predict that David Webber will now come
> in again and talk about what is lacking about W3C Schema, and why CAM
> is
> needed;)
>
> Joe
>
> Joseph Chiusano
> Associate
> Booz Allen Hamilton
>
> 700 13th St. NW, Suite 1100
> Washington, DC 20005
> O: 202-508-6514
> C: 202-251-0731
> Visit us online@ http://www.boozallen.com
>
> -----Original Message-----
> From: stephen.green@systml.co.uk [mailto:stephen.green@systml.co.uk]
> Sent: Wednesday, May 03, 2006 2:20 PM
> To: ubl-dev@lists.oasis-open.org
> Subject: RE: [ubl-dev] SBS and Restricted Data Types
>
> Thanks Joe
>
> Quoting Chiusano Joseph <chiusano_joseph@bah.com>:
>
>> 2 questions also come to mind:
>>
>> (1) Regarding the approach proposed just below: The XPath.xml subset
>> definition files do not specific the data type for an element. Given
>> that the set of valid constraining facets for an XSD simple data type
>> varies according to the data type (e.g. for a data type of xsd:date,
>> a
>
>> constraining facet of "maxExclusive" is valid, but that same
>> constraining facet is not valid for xsd:string), it would therefore
>> not be possible to validate that a given constraining facet (what we
>> call a "restriction-pattern" below) in an XPath.xml subset definition
>> file is valid given the element's data type.
>
> I guess these are just the things we'd need to consider for a
> methodology extension to cover implementation-specific, more granular,
> tighter subsets and a schema extension for such definitions.
>
>>
>> Therefore, during validation one would need to refer back to the full
>> schema for the data type - unless the data type was also included in
>> the XPath.xml subset definition file. Is this correct?
>>
>
> Yes, one has to provide a developer (or auto-generation tool) with
> both subset definition and the parent schemas. My guess is (not having
> examined it in detail recently) one has to do this anyway, unless
> there is reason to
> combine all the schema information into the subset definition :-(
>
>> (2) Wouldn't the restriction-pattern also need to be added to the
>> XPath file (the one with the actual XPaths) as well, since we include
>> cardinality information in that file?
>
> Thanks for pointing out that these files do have cardinality info; at
> first we didn't do this. I might have given a bit of false information
> in a previous posting about this (OK, I admit it - I forgot, sorry).
> I guess my emails aren't normative, perhaps not even informative in
> this case :-)
>
> As above, this kind of granularity was out of scope (probably still
> is) for the SBS and its use case for subsets in general. Only
> implementation specific subsets are likely, I'd think, to need such
> detail. If we think of extending the methodology we could consider
> these things. Any chance you could send this and anything like it to
> the SBSC or UBL TC using the comments form as this gives us permission
> to use it in UBL? I think this is acceptable outside of a review
> period but there may be a review coming in a few months time anyway.
>
> We wouldn't, perhaps (a guess) be providing such files with the actual
> SBS since it doesn't subset to that degree (deliberately, in view of
> its purpose to cater for the widest range of implementations). It
> seems best to keep to a max level of detail being cardinality for the
> SBS. Even that isn't yet subsetted in the existing SBS owing to its
scope.
>
> Thanks again
>
> All the best
>
> Steve
>
>>
>> Joe
>>
>> Joseph Chiusano
>> Associate
>> Booz Allen Hamilton
>>
>> 700 13th St. NW, Suite 1100
>> Washington, DC 20005
>> O: 202-508-6514
>> C: 202-251-0731
>> Visit us online@ http://www.boozallen.com
>>
>> -----Original Message-----
>> From: stephen.green@systml.co.uk [mailto:stephen.green@systml.co.uk]
>> Sent: Wednesday, May 03, 2006 4:27 AM
>> To: ubl-dev@lists.oasis-open.org
>> Subject: Re: [ubl-dev] SBS and Restricted Data Types
>>
>> Hi Joe
>>
>> For example, in the ...-XPath.xml subset definition file you would
>> have
>>
>> <Element name="Note" type="NoteType" prefix="cbc"
>> uri="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponen
>> t
>> s-
>> 1.0"
>>
>> minOccurs="0" maxOccurs="1" text="">
>>
>> <Attribute name="languageID" use="optional"
>> type="xsd:language"/>
>> </Element>
>>
>> which could be restricted to
>>
>> <Element name="Note" type="NoteType" prefix="cbc"
>> uri="urn:oasis:names:specification:ubl:schema:xsd:CommonBasicComponen
>> t
>> s-
>> 1.0"
>>
>> minOccurs="1" maxOccurs="1" text="">
>>
>> <Attribute name="languageID" use="optional"
>> type="xsd:language"/>
>> </Element>
>>
>> making the Note mandatory. This way the SBS mechanism allows
>> restrictions to cardinalities. A reminder that the resulting
>> instances
>
>> have to be valid according to non-subset schemas too (in the SBS
>> methodology) so only restrictions and not extensions are likely to
> work.
>>
>> For facets we decided not to create a mechanism for the committee
>> spec
>
>> definitions which would restrict string content - this is to avoid
>> interoperability problems. If you are in a position to make use of
>> facet restriction of strings, say with patterns, beyond just
>> restricting cardinality, I'd suggest adapting the subset definition
>> to
>
>> this in a way which agrees with your business partners but this is at
>> your own discretion and outside of scope for the SBS methodology (at
>> present). If you wanted, you could perhaps join the TC to get your
>> method made public to help adoption and interoperability. In the
>> meantime how about an attribute added here
>>
>> minOccurs="1" maxOccurs="1" text="" restriction-pattern="...">
>>
>> I say 'restriction-pattern' because it has to obey XSD rules to still
>> be valid for XSD - the resulting string, say, has to be schema valid
>> in the document instance.
>>
>> This would need an extension to the subset definition schemas (XSD
>> and
>
>> RNG).
>>
>> How does this answer things? I'd consider whether allowing
>> restrictions as much as this doesn't create problems but it does make
>> sense for implementers'
>> own subsets so maybe UBL's SBSC should consider it as a specified
>> extansion.
>>
>> As for how to create susbets in practical terms, along the SBS lines,
>> there are a few things to consider
>> + how to model the subset (the Small Business SC simply pruned UBL
>> + schemas) how to generate subset definitions (SBSC used scripting)
>> + the need to create one's own uuid for each definition how to
>> + publish
>
>> + (SBSC
>>
>> + was created to create the definitions as UBL committee
>> specifications and premanently publish them as such in
>> http://docs.oasis-open.org/ubl/ for widest use and
>> interoperablility)
>> + how to associate the subset definitions (and maybe codelist files,
>> + etc)
>> with the business process definitions and trading partner
agreements
>> (the SBS methodology only provides a mechanism for doing this with
>> ebXML)
>>
>> A further point is that restrictions of enumeration values are a
>> special case.
>> Say you wanted to restrict a code - there is the Codelist Methodology
>> for that (in progress for UBL in general but version 0.3 is for UBL
>> 1.0).
>> If you wanted to restrict an Identifier to add enumerations (as well
>> one might for an implementation, for example with a tax type ID) then
>> I hope the same codelist methodology could be used, perhaps creating
>> one's own genericode files for the identifiers and codelist
>> association files to relate them to the individual instances
>> (document
>
>> contexts) of the IDs in the documents.
>>
>> All this relies somewhat on one's being in a position to create one's
>> own subset definitions, codelist genericode files and association
>> files and to associate them with the actual transaction arrangements
>> and publish them.
>> The SBS especially provides all this somewhat to aid interoperability
>> as widely as possible and also to aid adoption where the above said
>> position is limited.
>>
>> All the best
>>
>> Stephen Green
>>
>>
>>
>>
>>
>>
>> Quoting Chiusano Joseph <chiusano_joseph@bah.com>:
>>
>>> Please pardon me if this question has been asked before on this list
>>> (my searches indicated the contrary):
>>>
>>> In terms of the SBS, what is the best way (if any) to restrict data
>>> types of a UBL schema for an specific implementation? Whether it is
>>> a
>
>>> 1.0 or 2.0 schema does not matter for purposes of this question (at
>>> least I don't believe so).
>>>
>>> For example, what if one had a need to define an xsd:minOccurs or
>>> xsd:maxOccurs facet for an xsd:string data type, for their own
>>> implementation?
>>>
>>> Thanks,
>>> Joe
>>>
>>> Joseph Chiusano
>>> Associate
>>> Booz Allen Hamilton
>>>
>>> 700 13th St. NW, Suite 1100
>>> Washington, DC 20005
>>> O: 202-508-6514
>>> C: 202-251-0731
>>> Visit us online@ http://www.boozallen.com
>>> <blocked::http://www.boozallen.com/>
>>>
>>>
>>
>>
>>
>>
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>
>
>
>
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