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Re: p:validate-with-xml-schema

From: Florent Georges <fgeorges@fgeorges.org>
Date: Fri, 26 Sep 2008 17:54:08 +0200
Message-ID: <ebaca5bf0809260854i4cc8bc96x4e36165c4ba86cef@mail.gmail.com>
To: "James Garriss" <james@garriss.org>
Cc: "XProc Dev" <xproc-dev@w3.org>

  Hi,

  Adding a boolean output telling the validation has succeeded or not
could be a good idea (I am not sure), but making that the main result
is not IMHO.  As far as I've seen, most of the time we do not want to
know if the document is valid or not, but we want to plug validation
in between two steps: if the document is valid, it is forwarded to the
following step (and by the way, doing so, the infoset is augmented),
if not an error is thrown.

  Actually the requirement of getting true or false from a validation
step seems quite rare to me.  But that just my limited experience.

  Regards,

-- 
Florent Georges
http://www.fgeorges.org/


2008/9/26 James Garriss <james@garriss.org>:
> Well, first, thank you for giving me something to work with.  I appreciate
> that, and I'll try and get that running today.
>
> Second, I think you're right, that's clumsy.  If a lot of people need the
> pvsi on the output, great, I'm glad XProc gives it to them.  But a lot of
> people use XML Schema to find out if an XML is valid or not.  It's my
> opinion that the validation result needs to be really simple to access.
>  Would it be reasonable to add a second output port to
> p:validate-with-xml-schema?  Something like this:
>
>     <p:output port="valid" primary="false"/>
>
> If the document validates, then the output would be similar to the output of
> p:compare:
>
>    <c:result>true</c:result>
>
> or
>
>   <c:result>false</c:result>
>
> Alternatively, you could do this:
>
>   <p:output port="result" primary="false"/>      <-- true/false c:result
> here
>   <p:output port="pvsi" primary="false"/>        <-- pvsi here
>
> I assume that I'm not the first person to think of this.  If so, why hasn't
> this been done already?  If not, is there someplace that I should go to make
> this an official suggestion to the WG?
>
> James Garriss
> http://garriss.blogspot.com
>
>
>
> ________________________________
> From: Norman Walsh <ndw@nwalsh.com>
> Date: Fri, 26 Sep 2008 08:32:07 -0400
> To: XProc Dev <xproc-dev@w3.org>
> Subject: Re: p:validate-with-xml-schema
> Resent-From: XProc Dev <xproc-dev@w3.org>
> Resent-Date: Fri, 26 Sep 2008 12:32:55 +0000
>
> James Garriss <james@garriss.org> writes:
>
>> I guess I don't know how everyone else uses XML Schema (or RelaxNG or
>> Schematron), but when I do schema validation I want to know if my XML is
>> valid or not (and if not, why not?).
>>
>> Two questions, if I may:
>>
>> 1) Why does this step return a PSVI instead of true/false?  I'd like to
>> understand the thinking.
>
> In the case of W3C XML Schema at least, schema validation performs
> type assignment and augments the infoset with new information. For
> many users, this new type information is at least as important as
> validity checking.
>
>> 2) How can I get it to return true/false?
>
> For better or worse, I think the best thing you can do today is define
> your own pipeline that returns the result you want:
>
> <p:declare-step xmlns:p="http://www.w3.org/ns/xproc"
>   xmlns:c="http://www.w3.org/ns/xproc-step"
>   type="px:is-valid"
>   name="is-valid">
> <p:input port="source" primary="true"/>
> <p:input port="schema" sequence="true"/>
> <p:output port="result"/>
> <p:option name="mode" select="'strict'"/>
>
> <p:try>
>   <p:group>
>     <p:validate-with-xml-schema assert-valid="true">
>       <p:input port="source">
>  <p:pipe step="is-valid" port="source"/>
>       </p:input>
>       <p:input port="schema">
>  <p:pipe step="is-valid" port="schema"/>
>       </p:input>
>       <p:with-option name="mode" select="$mode"/>
>     </p:validate-with-xml-schema>
>     <p:choose>
>       <p:when test="/*">
>  <p:identity>
>    <p:input port="source">
>      <p:inline><c:result>true</c:result></p:inline>
>    </p:input>
>  </p:identity>
>       </p:when>
>       <p:otherwise>
>  <!-- this can't happen -->
>  <p:identity>
>    <p:input port="source">
>      <p:inline><c:result>false</c:result></p:inline>
>    </p:input>
>  </p:identity>
>       </p:otherwise>
>     </p:choose>
>   </p:group>
>   <p:catch>
>     <p:identity>
>       <p:input port="source">
>  <p:inline><c:result>false</c:result></p:inline>
>       </p:input>
>     </p:identity>
>   </p:catch>
> </p:try>
> </p:declare-step>
>
> If you put the preceding declaration in your pipeline, then you can call
> it as a step:
>
> <px:is-valid>
>   <p:input port="source">
>     ...
>   </p:input>
>   <p:input port="schema">
>     ...
>   </p:input>
> </px:is-valid>
>
> and it will produce <c:result>true|false</c:result> on its primary
> output port. *And* Calabash 0.6.2, released this morning, will in fact
> run it. :-)
>
> On the one hand, this may seem like a fairly clumsy answer. On the
> other, you can stick this pipeline, and other utility pipelines that
> you write, in a library, import that library, and then it just becomes
> another step you can call.
>
> Support for calling declared pipelines in Calabash is very fragile,
> but I'm working on it.
>
> I don't think p:import works yet, but I'm working on that too.
>
>                                         Be seeing you,
>                                           norm
>
> --
> Norman Walsh <ndw@nwalsh.com> | When we are tired, we are attacked by
> http://nwalsh.com/            | ideas we conquered long ago.-- Nietzsche
Received on Friday, 26 September 2008 15:54:50 GMT

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