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Subject: Re: [ubl-dev] CCTS_CCT Defined CCT but not used
Good question. I'm probably not the ideal person to answer this but I reckon it goes something like this: If you are customising UBL or if you are writing another language which you want to interoperate with UBL you will want to have good alignment of datatypes. If you are trying to align using a language based on EDI rather than XML then the UN/CEFACT CCT spec aims to give you a lot of commonality with other languages written to comply with it. This includes use of a common set of core component types (the CCTs) which are defined in the UN/CEFACT CCT Specification (CCTS). If on the other hand you are using XML then you might get even better alignment of datatypes by using a common XML representation of those CCTs. One way to define that representation of the CCTs is with W3C XML Schema. This is the method chosen for not just UBL but several other key standards based on CCTS / XML. A key set of these all chose early on to use the same Schema for their CCTs in order to maximise interoperability (to avoid pitfalls due to differences in how their CCTs were represented like whether a supplementary piece of metadata was an element or an attribute). If you want to do the same with a custom document or even a custom (or alternative standard) language then you can use the same CCT schema as a basis for your datatypes to ensure you are starting with best possibilities for alignment of your datatypes with the other CCTS-based languages. This is one possibility; another is to just implement the CCTs in any way you choose and just seek to conform to the CCTS - OK if you are implementing something very different to UBL, etc (say written in JSON or RDF or EDI, for the sake of argument) but perhaps not ideal if you are doing something closer to UBL (or OAGIS or GS1 -XML...) and want to make life easier for mapping and translating between these languages. Plus there is the factor that you might want to think about future alignment with UN/CEFACT standards like the cross-industry trading docs. Sorry, this is longwinded. I haven't even got to the main point yet: Which is that 'using' the CCT datatypes (basing your unqualified or qualified datatypes, as CCTS calls them, on those CCTs) does not require any link between the W3C XML Schema definition of you datatypes and the corresponding W3C XML Schema definition of the base CCTs. It just means you need to look at the CCT when you write your datatype so you make your datatype a logical specialisation of that CCT (see CCT Spec if you want to know more, I'm a bit behind on how it goes these days). So it is kind of there in the schema set for reference, mainly because the W3C XML Schema specs don't seem to cater for this kind of derivation at a conceptual level - only at an implementation level (although we never really decided if the use of the schema derivation mechanism in XML Schema was appropriate for showing derivation of a 'datatype' on a 'core type' - those terms being the CCTS-semantics ones). So in short, unless you are extending UBL or writing a language to align with UBL or its CCTS neighbours, you can safely ignore that CCT schema (even remove it if you like). Just treat it as technical reference material. But maybe think of it as like an 'interface' in the object oriented sense (though I get the impression it isn't meant to be strictly conformant to OO principles). Apologies for long treatise. Again, this is not necessarily the account of this everyone else designing UBL would have agreed with, just my own take on what was done. Maybe the others involved in including the CCT schema in the set are no longer even on this list so I thought I'd better pipe in. Best regards Steve Stephen D Green 2009/6/18 <jaymuz@optusnet.com.au>: > In CCTS_CCT_SchemaModule-2.0.xsd the namespace: > > xmlns:cct="urn:un:unece:uncefact:data:specification:CoreComponentTypeSchemaModule:2" > > is defined however no elements or attributes with the cct prefix appear in the schema document. > > Why is that? > > John > > --------------------------------------------------------------------- > To unsubscribe, e-mail: ubl-dev-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: ubl-dev-help@lists.oasis-open.org > >
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