[dsdl-discuss] Re: FW: DSDL: Physical validation

One other important example to add to the list is validating Canonical XML.
And XML Digital Signatures needs to go on the list of use cases too.

But I don't think any of them belong in DSDL. Another standard
would be appropriate, perhaps invoking the DSDL framework, because

 1) It is undoubtedly a useful thing to have
 2) It is validating markup practices not the schema of the document.
 3) It requires a different technology to implement: they probably
   cannot be done on SAX streams for example
 4) I am not keen to make DSDL an open-ended grab-bag for
new technology: lets standardize pre-existing things that
have proved themselves!

Cheers
Rick

Martin Bryan wrote:

>On Tue, 2004-09-28 at 09:48, Jeni Tennison wrote:
>
>
>>Hi Martin, Alex,
>>
>>I had a chat with Pete Rogers and Thomas Nichols after Alex's DSDL
>>talk, trying to get to the bottom of Pete's points about validating
>>the prefixes that are used within a document.
>>
>>My conclusion from that chat was that, while most of DSDL is
>>(properly) based on validating the logical structure of an XML
>>document, there should be a Part that looks at validating its
>>
>>
>*physical* structure.
>
>
>>Here are some examples of the kinds of physical validation that one
>>might require:
>>
>> * The document must use namespaces sanely (as defined in
>> http://lists.xml.org/archives/xml-dev/200204/msg00170.html)
>>
>> * The document must associate the namespace
>> "http://www.w3.org/1999/XSL/Transform" with the prefix "xsl"
>>
>> * Namespace declarations must be placed on particular elements (this
>> requirement is particularly relevant when mixing namespaces and
>>
>>
>DTDs;
>
>
>> see eBooks as an example)
>>
>> * Content of the <script> element must be escaped with a CDATA
>>section
>>
>> * The <foo> element must be inserted using the &foo; entity
>>
>> * Specific characters must be represented using particular entities
>> (e.g. non-breaking spaces as &nbsp;)
>>
>> * Specific characters must be included as native characters rather
>>
>>
>than
>
>
>> as entities or character references
>>
>> * Character references must use the hexadecimal version rather than
>>
>>
>the
>
>
>> decimal version of the character's codepoint
>>
>> * Particular elements, when empty, must be represented with a start
>>
>>
>and
>
>
>> end tag rather than an empty tag (and vice versa).
>>
>>(I have personal experience with most of the above constraints.)
>>
>>Of course, there's scope for specifying other physical constraints,
>>such as which kind of quotes should be used around attribute values;
>>what whitespace is allowed within tags or in element-only content; and
>>
>>
>so on.
>
>
>>A physical schema language would have to decide which physical
>>features to constrain.
>>
>>Is there any room in DSDL for such a schema language?
>>
>>Cheers,
>>
>>Jeni
>>
>>
>
>This proposal needs to be considered in our discussion on DSDL in
>Amsterdam next month. Not sure it's really in our remit, but it does
>carry implications for what a pipelining approach to validation
>management might be able to provide in the way of additional
>functionality
>
>Martin Bryan
>
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