(r1) AdqlFunctionPrefixes < IVOA

IVOA Web>IvoaDAL>ADQL>AdqlFunctionPrefixes (revision 1) (raw view)~~EditAttach~~

---++ ADQL function names

The ADQL standard itself does not impose any restrictions on the names that may be used for user defined functions.

To avoid name collisions when solving common problems, we should prefix user defined functions with an acronym that represents the institute, department or archive where the function originates.

If the [[http://www.roe.ac.uk/ifa/wfau/][Wide Field Astronomy Unit (WFAU)]] prefix user defined functions with =wfau=:
<verbatim>
    wfau_align()
    wfau_convert()
</verbatim>

If the [[http://www.g-vo.org/pmwiki/][German Astrophysical Virtual Observatory (GAVO)]] adopted a similar naming convention:
<verbatim>
    gavo_align()
    gavo_convert()
</verbatim>

This would enable the VO to support different implementations of similar functions without conflicts:
<verbatim>
    wfau_align()
    gavo_align()

    wfau_convert()
    gavo_convert()
</verbatim>

Note that the prefix indicates the origin of the function implementation, not the identity of the TAP service providing the function.
If another TAP service uses one of the WFAU function implementations, the function name should keep the =wfau= prefix to indicate the origin of the implementation.
<verbatim>
    wfau_align()
</verbatim>

If one of the GAVO functions is adopted as part of an IVOA standard, then we could use the =ivo= prefix to indicate that it is an IVOA standard function.
<verbatim>
    ivo_align()
</verbatim>

For backwards compatibility, a TAP services could provide the same function using different names:
<verbatim>
    gavo_align()  -- original GAVO version
    ivo_align()   -- IVOA standard version
</verbatim>

The same TAP service could also provide the WFAU implementation of the align() function:
<verbatim>
    gavo_align()  -- original GAVO version
    wfau_align()  -- alternative WFAU version
    ivo_align()  -- IVOA standard  version
</verbatim>

The following table acts as an informal registry of function prefix names.

|*prefix*|*name*|*link*|
|ivo|IVOA standard functions|http://ivoa.net/|
|wfau|Wide Field Astronomy Unit, Institute for Astronomy, University of Edinburgh|http://www.roe.ac.uk/ifa/wfau/|
|gavo|German Astrophysical Virtual Observatory|http://www.g-vo.org/pmwiki/|

If you would like to to participate, please add your prefix to the table.

If you are adding new user defined functions to your TAP services, consider adding a prefix to the function name to indicate where the function comes from.

If you already have user define functions in your TAP services, introduce alternative names for them with an appropriate prefix and gradually encourage your users to use the prefixed names.

<br/>
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Topic revision: r1 - 2017-04-12 - DaveMorris

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