We had exactly the same problems, with UBL-invoice also.
We did a XSD validation, then a schematron validation to check the
specific UBL-invoice uses of the context. The result of these two
validations decided if a XML document was "conform", so acceptable or
not. This was a technical check, which decides if my application can or
not manipulate the document.
Then, human experts were checking the XML content, to see if data was
legal or not, "legal" being a business word grouping all business rules.
Rules were so complicated that we did not write any schematron or
anything else, but today, I'd put a Drools engine to do business
validation behind.
So, I totally agree with you for the two phrases and phases.
Best,
Christophe
Le 04/01/2018 à 07:59, Frank Steimke a écrit :
> A remark to Mikes comment: we are dealing with the exchange of structured
> messages between ict systems. The structure is coded in XML.. We use XML
> Schema (XSD together with Schematron) as a language, which describes the
> agreement of the involved parties about the messages to be exchanged. We can
> make statements about the allowed structures (syntax) as well as (parts of)
> the semantic of messages. A typical scenario is the exchange of electronic
> invoices. Syntax and semantic can be defined in terms of UBL Schema and
> additional interoperability specifications and business rules like european
> EN 16931, which has a lot of schematron rules.
>
> In this scenario, we try to distinguish between the words “validation” and
> “assessment”. In fact, from our point of view, we see them as two distinct
> phases on the receiver’s side.
>
> Validation answers the question: does the exchanged document fulfil all
> requirements of all involved Schemas? Validation should be a binary
> decision: the message, which is an XML document, is valid to a Schema, or it
> is not valid. We think that this is true for XML Schema (XSD), but we are
> not sure if this is also true for Schematron Schema. Is a document with only
> on failed-assertion, which @flag or @role is not error but warning, valid or
> is it not valid? However, validation should be a clear and deterministic
> yes-or-no decision, and this idea is supported in the definition of a
> schematron processor in the ISO Standard for Schematron.
>
> Assessment, on the other hand, is the second phase on the receiver’s side.
> It means: decide whether you will accept or reject the message. This
> decision is of course based on the result of validation. It should be easy
> if there are no validation errors (you are obliged to accept), but in case
> of validation errors, you are not always obliged to reject. Assessment
> basically means: can we accept a message although it is not valid? Again,
> this is especially important when the validation error is in fact a warning
> in case of a Schematron business rule.
>
> We have just discovered that the distinction between these two phases may be
> useful, because it can give a lot more flexibility, especially when you try
> to introduce new vocabularies for message exchange and you are not sure
> about all the business rules. In fact, you can find a java application which
> implements validation and assessment in Github at
> https://github.com/itplr-kosit/validationtool
>
> We are pretty much interested about comments from the experts, whether the
> distinction between these two phrases (and phases) makes sense and seems to
> be useful.
>
> Thanks in advance,
> Frank Steimke
>
>
> -----Ursprüngliche Nachricht-----
> Von: Michael Kay [mailto:]
> Gesendet: Mittwoch, 3. Januar 2018 17:25
> An: bryan rasmussen <>
> Cc: Costello, Roger L. <>;
> Betreff: Re: [xml-dev] Need a language whiz: An XML Schema "specifies" how
> data is to be structured? "describes"? "constrains"?
>
> The essence of the semantics of XSD is that the specification defines a
> process, variously called "validation" or "assessment", that takes a schema
> and an instance document as input and produces an assessment outcome as its
> result.
>
> assess(schema, instance) => outcome
>
> (It's slightly more complicated than that because you can specify other
> inputs to the assessment, e.g. strict/lax).
>
> The specification does not use any specific term (such as "describes" or
> "constrains") for the relationship between a schema and the set of instance
> documents for which assessment has an outcome labeled "valid". You're
> perfectly welcome to use a term such as "describes" for this relationship if
> you wish, but it's not a term-of-art in XSD itself; so if you use it, you
> should say carefully what you mean by it.
>
> Michael Kay
> Saxonica
>
>
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