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   Re: [xml-dev] Making a silk purse out of the schema sows ear - was [xml-

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As noted since I don't know the ASL syntax I could be interpreting
those examples you pointed to completely wrong.

Cheers,
Bryan Rasmussen

On 2/9/06, bryan rasmussen <rasmussen.bryan@gmail.com> wrote:
> Well, looking at what you pointed to the first example also has
> sorting, which is somewhat outside the bounds of what anyone has
> discussed as validation before. As for the other ones I'm not exactly
> sure what you're validating (maybe due to not having time to learn ASL
> syntax)?
>
> Actually this one
> http://reflex.gforge.inria.fr/tutorial/weather-report/schema2.asl
> looks like you're changing the value of the temp attributes if scale
> attribute equals the Fahrenheit scale.
>
> Another in the list of schema languages that people don't note too
> often is DSD http://www.brics.dk/DSD/
>
> Cheers,
> Bryan Rasmussen
>
>
>
> On 2/9/06, Philippe Poulard <Philippe.Poulard@sophia.inria.fr> wrote:
> > This is a remark that has been made in comp.text.xml
> >
> > Unlike schematron, ASL computes content models, which allow
> > tools such as editors to predict which element is allowed ; schematron
> > is not predictive, it can only warn that a rule has not been followed
> > AFTER the user has made the mistake, for example by inserting an element
> > that is not allowed.
> >
> > There is a great difference between a tool such as schematron that
> > checks if everything is right in the XML document, and other schema
> > technologies (DTD, RelaxNG, WXS, ASL) that are able to draw up a
> > contextual list of XML material (attributes, elements, text) that is
> > legal to use. You can consider that the Active Schema Language is like a
> > deep integration of known schemata (DTD, RNG, WXS) with an assertion
> > language such as schematron ; a deep integration goes further than using
> > schematron in WXS or RNG because even if they are located in the same
> > XML instance, they are processed separately.
> >
> > Here is a mix of RNG + schematron :
> > <?xml version="1.0" encoding="UTF-8"?>
> > <grammar ns="" xmlns="http://relaxng.org/ns/structure/1.0";
> >    xmlns:sch="http://www.ascc.net/xml/schematron";>
> >    <start>
> >      <element name="table">
> >        <oneOrMore>
> >          <element name="column">
> >            <sch:pattern name="Check to have the same number of cells in
> > each column" id="cells">
> >              <sch:rule context="column">
> >                <sch:assert test="count(../column[1]/cell) =
> > count(cell)">The number of cells in this
> >                  column should be the same as in the firtst column,
> > expected <sch:value-of
> >                    select="count(../column[1]/cell)"/> but got
> > <sch:value-of select="count(cell)"/>.
> >                </sch:assert>
> >              </sch:rule>
> >            </sch:pattern>
> >            <oneOrMore>
> >              <element name="cell">
> >                <empty/>
> >              </element>
> >            </oneOrMore>
> >          </element>
> >        </oneOrMore>
> >      </element>
> >    </start>
> > </grammar>
> >
> > Anyway, another point that is not covered by schematron is the
> > capability to design smart data types such as semantic data types, as
> > shown in this example :
> > http://reflex.gforge.inria.fr/tutorial.html#N800F69
> > This is a very basic problem that known schematas can't resolve.
> > I think that neither WXS nor schematron could perform the same result
> > (just tell me how if I'm wrong)
> >
> > bryan rasmussen wrote:
> > > In Schematron - however going for xslt implementation of schematron by
> > > using the current function:
> > >
> > > <sch:rule context="table/column[1]">
> > >     <sch:report
> > > test="following-sibling::column[count(cell)&gt;current()[count(cell)]]"
> > >     >cells need to be the same number per column
> > > </sch:report>
> > >
> > > </sch:rule>
> > >
> > > Cheers,
> > > Bryan Rasmussen
> > >
> > >
> > >
> > >
> > > On 2/9/06, Philippe Poulard <Philippe.Poulard@sophia.inria.fr> wrote:
> > >
> > >>hi,
> > >>
> > >>IMHO, the main difficulty that schema technologies encounter is their
> > >>poor capabilities to express constraints because they are hard-coded in
> > >>the schema. This is the case for occurrence constraints and content
> > >>model definitions.
> > >>
> > >>I have experimented a schema language that allows to compute the
> > >>occurrence constraints dynamically and that allows to switch from a
> > >>declarative language to an imperative one, which increases dramatically
> > >>the expressiveness of the schema. The idea is to push back the limits of
> > >>the declarative language when they are reached.
> > >>
> > >>An example :
> > >>a RelaxNG user was complaining about a constraint that he couldn't
> > >>express : he had to design a <table> with any <column>s but <column>s
> > >>should have the same number of <cell>s
> > >>
> > >>I respond that he could consider an alternative schema technology, such
> > >>as these that I designed :
> > >><asl:element name="column">
> > >>   <asl:sequence>
> > >>     <xcl:if test="{ asl:element()/preceding-sibling::column }">
> > >>       <xcl:then>
> > >>         <asl:element ref-elem="cell" min-occurs="{
> > >>  $asl:max-occurs }" max-occurs="{ count( asl:element()/../column[1]/cell
> > >>  ) }"/>
> > >>       </xcl:then>
> > >>       <xcl:else>
> > >>         <asl:element ref-elem="cell" min-occurs="1"
> > >>  max-occurs="unbounded"/>
> > >>       </xcl:else>
> > >>     </xcl:if>
> > >>   </asl:sequence>
> > >></asl:element>
> > >>The full schema and the running results are available here :
> > >>http://groups.google.com/group/comp.text.xml/browse_thread/thread/d97cd4adf1964fdb/2f92e65b7ad48dff?hl=en#2f92e65b7ad48dff
> > >>
> > >>This demonstrates that a simple if-then-else statement allows to build a
> > >>made-to-measure content model with dynamic occurrence constraints.
> > >>
> > >>I named that schema language the Active Schema Language and I have an
> > >>almost full implementation of it in Java, called RefleX :
> > >>http://disc.inria.fr/perso/philippe.poulard/xml/active-tags/active-schema/active-schema.html
> > >>http://reflex.gforge.inria.fr/
> > >>You can read the examples, download the tool and play with it.
> > >>
> > >>Moreover, ASL allows to design smart data types ; there is a tutorial in
> > >>the RefleX web site that shows a semantic data type : the "temperature"
> > >>data type, which is able to parse "32F" and "20C" ; as this type is
> > >>used to augment the amount of information of the XML document, we can
> > >>sort a list of attributes of this type not on the string values but on
> > >>the typed values
> > >>http://reflex.gforge.inria.fr/tutorial.html#N800F69
> > >>
> > >>It is worth seeing because all the problems you consider in your message
> > >>are pointed out and solutioned in ASL.
> > >>
> > >>Michael Champion wrote:
> > >>
> > >>>I think the reality is that lots of people flipped the Bozo Bit on the
> > >>>XSD spec in 1999-2000.  They went in different directions, however:
> > >>>Some to alternative schema languages, some to radical simplification of
> > >>>XML to de-emphasize schemas altogether.
> > >>>
> > >>>
> > >>>
> > >>>In hindsight, had  people foreseen today's reality that we're stuck with
> > >>>XSD as what the mainstream user thinks of as the "real standard",
> > >>>clearly the energy would have been better spent debugging the wretched
> > >>>thing rather than trying to pretend it doesn't exist or trying to drive
> > >>>a stake thru its heart.  I'm more interested in discussing what to do
> > >>>going forward given the current mess.  The problems I see are:
> > >>>
> > >>>
> > >>>
> > >>>- The W3C is more interested in moving the XSD spec forward than fixing
> > >>>its numerous ambiguities.  (Their pushback is that the people who want
> > >>>to fix it are not represented on the WG, and the people who have skin in
> > >>>the game want to move forward).
> > >>>
> > >>>- RELAX NG is clearly "better" for textual documents but doesn't have
> > >>>much support for the data-oriented use cases. (Sure you can plug in the
> > >>>XSD type system, but that's a big part of the problem).  We now have an
> > >>>unpleasant situation of fragmentation where there's little mainstream
> > >>>tool support for RELAX NG due to lack of demand, exploitation of its
> > >>>geek chic (partly to strike a blow against the empire, I suppose), with
> > >>>the result that the normative definitions of Atom and ODF can't be used
> > >>>with most commercial XML tools.  Maybe a good guerilla tactic in the
> > >>>open source wars, but for the moment it's the innocent who suffer the
> > >>>collateral damage.
> > >>>
> > >>>
> > >>>
> > >>>- Schematron is moving forward as an ISO standard and has some good
> > >>>implementations but has few normative references in vertical industry
> > >>>standards nor mindshare.  (Correct me if I'm wrong about the normative
> > >>>references).
> > >>>
> > >>>
> > >>>
> > >>>- Lots of people complain about the limitations of XSD that Schematron
> > >>>addresses and the W3C doesn't plan to, especially the lack of occurrence
> > >>>constraints.
> > >>>
> > >>>The best way forward that I can see is to encourage end users to
> > >>>employ XSD + Schematron as necessary, and encourage W3C to address XSD's
> > >>> bugs and ambiguities before adding more onto an unstable foundation.
> > >>>What does that miss that the world actually values? (as much as it
> > >>>depresses me to say it, the world doesn't seem to value RELAX NG's
> > >>>elegance and mathematical foundation very much).
> > >>>
> > >>
> > >>--
> > >>Cordialement,
> > >>
> > >>               ///
> > >>              (. .)
> > >>  --------ooO--(_)--Ooo--------
> > >>|      Philippe Poulard       |
> > >>  -----------------------------
> > >>  http://reflex.gforge.inria.fr/
> > >>        Have the RefleX !
> > >>
> > >>-----------------------------------------------------------------
> > >>The xml-dev list is sponsored by XML.org <http://www.xml.org>, an
> > >>initiative of OASIS <http://www.oasis-open.org>
> > >>
> > >>The list archives are at http://lists.xml.org/archives/xml-dev/
> > >>
> > >>To subscribe or unsubscribe from this list use the subscription
> > >>manager: <http://www.oasis-open.org/mlmanage/index.php>
> > >>
> > >>
> > >
> > > -----------------------------------------------------------------
> > > The xml-dev list is sponsored by XML.org <http://www.xml.org>, an
> > > initiative of OASIS <http://www.oasis-open.org>
> > >
> > > The list archives are at http://lists.xml.org/archives/xml-dev/
> > >
> > > To subscribe or unsubscribe from this list use the subscription
> > > manager: <http://www.oasis-open.org/mlmanage/index.php>
> > >
> > >
> >
> >
> > --
> > Cordialement,
> >
> >                ///
> >               (. .)
> >   --------ooO--(_)--Ooo--------
> > |      Philippe Poulard       |
> >   -----------------------------
> >   http://reflex.gforge.inria.fr/
> >         Have the RefleX !
> >
>




 

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