/[volute]/trunk/projects/registry/VODataService/VODataService.tex
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revision 5151 by msdemlei, Fri Sep 28 07:37:54 2018 UTC revision 5152 by msdemlei, Fri Sep 28 09:57:24 2018 UTC
# Line 2381  Line 2381 
2381    
2382  The VODataService schema defines two XML types that derive from  The VODataService schema defines two XML types that derive from
2383  \xmlel{vs:TableDataType}:  \xmlel{vs:VOTableType} and  \xmlel{vs:TableDataType}:  \xmlel{vs:VOTableType} and
2384  \xmlel{vs:TAPType}.    \xmlel{vs:TAPType}.  Following the move to VOTable-compatible type
2385    descriptions in TAP 1.1 \citep{todo:TAP1.1}, this version of
2386    VODataService deprecates the use of \xmlel{vs:TAPType}.  New software
2387    should only generate \xmlel{vs:VOTableType}s in \xmlel{tableset}s.
2388    
2389    
2390  % GENERATED: !schemadoc VODataService-v1.2.xsd VOTableType  % GENERATED: !schemadoc VODataService-v1.2.xsd VOTableType
# Line 2468  Line 2471 
2471    
2472  \noindent{\small  \noindent{\small
2473              a data type supported explicitly by the Table Access              a data type supported explicitly by the Table Access
2474              Protocol (v1.0).                Protocol (v1.0).  This is deprecated in VODataService 1.2,
2475                and even TAP 1.0 services are encouraged to declare
2476                their columns using VOTableType.
2477           \par}           \par}
2478    
2479  \vspace{1ex}\noindent\textbf{\xmlel{vs:TAPType} Type Schema Definition}  \vspace{1ex}\noindent\textbf{\xmlel{vs:TAPType} Type Schema Definition}
# Line 2550  Line 2555 
2555    
2556    
2557    
 The \xmlel{vs:TAPType} XML type provides an additional attribute,  
 \xmlel{size}, corresponding to the \verb|"size"| column from the  
 TAP\_SCHEMA.columns defined by the TAP standard  
 \citep{todo:TAP1.1}.\todo{deprecate}  
   
   
   
   
2558  Examples for column definitions:  Examples for column definitions:
2559  A representation of a string type using the  A representation of a string type using the
2560  \xmlel{vs:VOTableType} set of types:  \xmlel{vs:VOTableType} set of types:
# Line 2571  Line 2568 
2568  </column>  </column>
2569  \end{lstlisting}  \end{lstlisting}
2570    
 The same column described using the  
 \xmlel{vs:TAPType} set of types:\todo{deprecate this}  
   
 \begin{lstlisting}  
 <column>  
    <name> id </name>  
    <description> the object identifier </description>  
    <ucd> meta.id </ucd>  
    <dataType xsi:type="vs:TAPType"> VARCHAR </dataType>  
 </column>  
 \end{lstlisting}  
   
 The same column again described using the  
 \xmlel{vs:TAPType} set of types, assuming a fixed-length  
 string:\todo{deprecate this}  
   
 \begin{lstlisting}  
 <column>  
    <name> id </name>  
    <description> the object identifier </description>  
    <ucd> meta.id </ucd>  
    <dataType xsi:type="vs:TAPType" size="8" > CHAR </dataType>  
 </column>  
 \end{lstlisting}  
2571    
2572    
2573    
# Line 2602  Line 2575 
2575  can support any non-abstract type legally derived from  can support any non-abstract type legally derived from
2576  \xmlel{vs:TableDataType}.  However, in the context of a  \xmlel{vs:TableDataType}.  However, in the context of a
2577  \xmlel{vs:DataCollection} or \xmlel{vs:CatalogService}  \xmlel{vs:DataCollection} or \xmlel{vs:CatalogService}
2578  resource description, it is strongly recommended that either  resource description, it is strongly recommended that
2579  \xmlel{vs:VOTableType} or \xmlel{vs:TAPType} (or some other IVOA  \xmlel{vs:VOTableType}  be used to
2580  standard type derived from \xmlel{vs:TableDataType}) be used to  ensure maximum interoperability.  
 ensure maximum interoperability.  When the actual column type is not  
 well matched to a type from one of these standard sets, authors are  
 encouraged to use the \xmlel{extendedType} attribute to refer to  
 a more specific type.  Note that the ADQL standard  
 \citep{todo:ADQL2.2} defines an explicit mapping between  
 SQL types and VOTable types.  Thus, in the context of a  
 \xmlel{vs:CatalogService} resource description that supports a  
 TAP capability (perhaps in addition to other catalog services like  
 Simple Cone Search), use of the  
 \xmlel{vs:TAPType} data type is preferred.  
2581    
2582    When the actual column type is not
2583    well matched to a VOTable data type, authors are
2584  \begin{admonition}{Note}  encouraged to use the \xmlel{extendedType} attribute to refer to
2585  The motivation for providing two standard data type sets,  a more specific type.\todo{Say something about this and DALI xtype}.
        \xmlel{vs:VOTableType} and \xmlel{vs:TAPType}, is to maximize  
        the ease of generating the table description, particular as  
        part of the VO Standard Interface \citep{2017ivoa.spec.0524G}  
        and for legacy services.  The table description for  
        ``stand-alone'' SIA, SCS, and SSA services can be readily  
        generated using the \xmlel{vs:VOTableType} data types from  
        these interface's respective metadata queries.  Newer services  
        supporting TAP could generate its description using its  
        TAP\_SCHEMA queries.  
   
         
        The motivation for specifying a column's data type using the  
        \xmlel{xsi:type} mechanism is mainly to allow for the  
        possibility that the official TAP data types will evolve.  This  
        allows the IVOA to define new data type sets without updating  
        the VODataService standard.  Using non-IVOA-standardized data  
        type names is expected to undermine interoperability and so is  
        therefore discouraged.    
 \end{admonition}  
2586    
2587  \appendix  \appendix
2588    
# Line 2653  Line 2597 
2597  \item DataType/@arraysize no longer defaults to 1, and the  \item DataType/@arraysize no longer defaults to 1, and the
2598  interpretation of arraysize=1 as a scalar is withdrawn.  Use empty  interpretation of arraysize=1 as a scalar is withdrawn.  Use empty
2599  arraysize for scalars now.  arraysize for scalars now.
2600    \item Deprecating TAPType.
2601  \item Ported source to \ivoatex.  \item Ported source to \ivoatex.
2602  \end{itemize}  \end{itemize}
2603    

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msdemlei@ari.uni-heidelberg.de
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