Contents of /trunk/projects/registry/tapregext-erratum1/TREErr1.tex

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TREErr1: initial draft.


 1 \documentclass{ivoa} 2 \input tthdefs 3 4 \title{TAPRegExt Erratum 1: dataModel should contain anyURI} 5 6 \ivoagroup{DAL} 7 8 \author{% 9 Markus Demleitner} 10 11 \editor{Markus Demleitner} 12 13 % \previousversion[????URL????]{????Funny Label????} 14 \previousversion{This is the first public release} 15 16 17 \begin{document} 18 \begin{abstract} 19 This Erratum proposes to change the type of the dataModel element of 20 TAPRegExt \citep{std:TAPREGEXT} such that any URI is allowed. This is 21 necessary to accomodate the structure of identifier URIs implied by 22 StandardsRegExt, and also consistent with the other IVORNs in TAPRegExt. 23 The correction, however, requires a schema change. 24 25 \end{abstract} 26 27 28 29 \section{Proposed Change} 30 31 The definition of \texttt{dataModel/@ivo-id} in the schema that 32 accompanied the original REC-1.0 submission of TAPRegExt 33 \citep{std:TAPREGEXT} is erroneous. Like all other ivo-id attributes in 34 TAPRegExt, its type should have been xs:anyURI (instead of 35 vr:IdentifierURI, as originally defined). The text starting with "This 36 is fine" and ending with "in the schema for this attribute" in section 37 2.3 is wrong in the light of current Registry Working Group 38 recommendations and should be considered removed. 39 40 With this Erratum, http://www.ivoa.net/xml/TAPRegExt/TAPRegExt-v1.0.xsd 41 was updated, such that vr:IdentifierURI in line 160 now reads 42 vr:anyURI. Clients using local or otherwise cached copies of the schema 43 are advised to update to avoid flagging now correct documents as 44 invalid. No currently valid documents will become invalid with this 45 change. 46 47 \section{Rationale} 48 49 \texttt{dataModel/@ivo-id} was originally considered an unversioned 50 reference to a StandardsRegExt \citep{std:STDREGEXT} record. The 51 Registry Working Group now recommends standards to have IVORNs like 52 $$\texttt{ivo://ivoa.net/std/stdname\#item-1.0},$$ 53 i.e., what is referenced actually is a (versioned) entity within a 54 StandardsRegExt record rather than the record itself. 55 56 \texttt{vr:IdentifierURI} does not admit fragment identifiers, which is one 57 reason why all remaining \texttt{ivo-id} attributes in TAPRegExt have been 58 defined as \texttt{xs:anyURI}. 59 60 By now, the special role of \texttt{dataModel/@ivo-id} versus the other 61 \texttt{ivo-id} attributes -- in conflict with current Registry 62 recommendations -- is more than a mere inconvenience, as standards like 63 RegTAP need to use new-style standard identifiers. To allow this 64 without making both registry records and capability documents invalid, 65 the schema must be corrected. As we believe the impact on existing 66 clients and practices is minimal, we suggest a silent schema update. 67 68 The alternative, a change of the schema's target name space, on the 69 other hand, will certainly break existing clients unless they daringly 70 opted to ignore the namespace of the elements. 71 72 73 \section{Impact Assessment} 74 75 All existing valid capability records remain valid, as the domain of 76 \texttt{xs:anyURI} is a superset of the domain of 77 \texttt{vr:IdentifierURI}. It is conceivable that existing clients 78 validating against a built-in copy of the TAPRegExt schema or parsing 79 using a generated validating parser might reject capability records with 80 the new generalized data model identifiers. It seems highly unlikely, 81 though, that such implementations have actually been made. 82 83 Any functionality provided through non-validating parsers or 84 validating parsers using the IVOA-provided (or document-provided) 85 schema is not concerned. In particular, as comparison of data model 86 identifiers takes place character-by-character (ignoring case), even 87 legacy clients will be able to work with the new generalized data 88 model identifiers. 89 \appendix 90 \section{Changes from Previous Versions} 91 92 No previous versions yet. 93 % these would be subsections "Changes from v. WD-..." 94 % Use itemize environments. 95 96 97 \bibliography{ivoatex/ivoabib} 98 99 100 \end{document}