TAPRegExt-1_0-Erratum-01 < IVOA

IVOA Web>WebPreferences>TAPRegExt-1_0-Erratum-01 (2016-10-25, MarkusDemleitner) (raw view)
 <a id="tth_sEc1"/><h2>
1  Erratum Content</h2>

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The definition of   <span class="xmlel">dataModel/@ivo-id</span> in the schema that
accompanies the original REC-1.0 submission of TAPRegExt


	<a href="#std:TAPREGEXT" class="tth_citeref">
	(Demleitner et al., 2012)</a> is erroneous.  Like all other 
  <span class="xmlel">ivo-id</span> attributes in
TAPRegExt, its type should have been   <span class="xmlel">xs:anyURI</span> (instead of
  <span class="xmlel">vr:IdentifierURI</span>, as originally defined).  The text starting with "This
is fine" and ending with ïn the schema for this attribute" in section
2.3 is wrong in the light of current Registry Working Group
recommendations and should be considered removed.

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With this Erratum,
<a href="http://www.ivoa.net/xml/TAPRegExt/TAPRegExt-v1.0.xsd">http://www.ivoa.net/xml/TAPRegExt/TAPRegExt-v1.0.xsd</a>
is updated, such that   <span class="xmlel">vr:IdentifierURI</span> in line 160 now reads
  <span class="xmlel">xs:anyURI</span>.  
Clients using local or otherwise cached copies of the schema
are advised to update to avoid flagging now correct documents as
invalid.  No currently valid documents will become invalid with this
change.

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 <a id="tth_sEc2"/><h2>
2  Rationale</h2>

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  <span class="xmlel">dataModel/@ivo-id</span> was originally considered an unversioned
reference to a StandardsRegExt  record.  The
Registry Working Group now recommends standards to have IVORNs like

<br clear="all"/><table border="0" width="100%"><tr><td>
<table align="center" cellspacing="0" cellpadding="2"><tr><td nowrap="nowrap" align="center">
<tt><tt>ivo</tt><tt>:</tt><tt>/</tt><tt>/</tt><tt>ivoa</tt><tt>.</tt><tt>net</tt><tt>/</tt><tt>std</tt><tt>/</tt><tt>stdname</tt><tt>#</tt><tt>item</tt>&#8722;<tt>1</tt><tt>.</tt><tt>0</tt></tt>,</td></tr></table>
</td></tr></table>

 
i.e., what is referenced actually is a (versioned) entity within a
StandardsRegExt record rather than the record itself.

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  <span class="xmlel">vr:IdentifierURI</span> does not admit fragment identifiers, which is one
reason why all remaining   <span class="xmlel">ivo-id</span> attributes in TAPRegExt have been
defined as   <span class="xmlel">xs:anyURI</span>.

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By now, the special role of   <span class="xmlel">dataModel/@ivo-id</span> versus the other
  <span class="xmlel">ivo-id</span> attributes - in conflict with current Registry
recommendations - is more than a mere inconvenience, as standards like
RegTAP need to use new-style standard identifiers.  To allow this
without making both registry records and capability documents invalid,
the schema must be corrected.  As we believe the impact on existing
clients and practices is zero, we suggest a silent schema update.

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The alternative, a change of the schema's target name space, on the
other hand, will certainly break existing clients unless they daringly
opted to ignore the namespace of the elements.

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 <a id="tth_sEc3"/><h2>
3  Impact Assessment</h2>

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All existing valid capability records remain valid, as the domain of
  <span class="xmlel">xs:anyURI</span> is a superset of the domain of
  <span class="xmlel">vr:IdentifierURI</span>.  It is conceivable that existing clients
validating against a built-in copy of the TAPRegExt schema or parsing
using a generated validating parser might reject capability records with
the new generalized data model identifiers.  It seems highly unlikely,
though, that such implementations have actually been made.

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Any functionality provided through non-validating parsers or
validating parsers using the IVOA-provided (or document-provided)
schema is not concerned.  In particular, as comparison of data model
identifiers takes place character-by-character (ignoring case), even
legacy clients will be able to work with the new generalized data
model identifiers.

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Topic revision: r1 - 2016-10-25 - MarkusDemleitner
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