Fwd: IVOA Standard Documents - and other standards-defining documents

[Martin Hill]

Just briefly (hopefully not too curtly):

 > Choosing a namespace can be tricky.  When it changes, applications
 > break, so we can't be too cavalier.

Namespaces should not *change*!  If, later, we decide we want to 
organise our versioning differently, then we have *new* namespaces that 
apply to new versions.  That way nothing breaks, which is nice.  As you 
say, the namespace is just a string; the convention that it also points 
to a schema (say) or has a particular pattern (say) is purely for human 
use and should not be hardcoded, so we can use anything we like for the 
pre-release stages.

 > (Note that we didn't post the schemas at the http://www.ivoa.net/xml/
 > location until we had official WD releases.  Thus, in the pre-release
 > stage, you cannot resolve the namespace URI to the schema.)

Without pre-release versioning and consistent posting we are making life 
difficult. At AstroGrid we have the same problems as you Ray; until 
recently we were guessing which ADQL schema we had, and even now we 
don't have a SkyNode WSDL *version*. Every time the WSDL or schema is 
*changed* our software breaks.  Posting schemas to a permanent 
'immutable' location means that our software doesn't break when a new 
version comes out - because the new version will go to a new permanent 
location.

The idea of putting things up on the IVOA site is to settle a particular 
standard (or?); if that standard includes web interface descriptions 
then that must include WSDL, schemas, etc...  We can't agree that 
version x.x.x on IVOA is what we want if the WSDL/schemas they point to 
can change!

So:
 > be sure the ADQL standard document includes a link to the proper
 > location of the schema.  This will be a location on the Twiki until
 > the official WD release; then it is changed to the official release
 > location.

OK... as long as the twikki locations and contents are considered 
'immutable', ie each schema posting is permanent and does not change.

 > Ask to the document coordinator (Marco) to allow links to associated
 > schemas to be appear on the document download page.

OK... but... associated schemas should also be posted to the IVOA site 
(twiki or anywhere) as 'immutable' docs, for the same reasons.

A single page with locations of all these things sounds like an 
excellent idea.

Cheers,

Martin

Ray Plante wrote:

> On Wed, 31 Mar 2004, Martin Hill wrote:
> 
>>Can we please include *all* the relevent schemas/etc along with the pdf 
>>documents?  That is, we should also move v0.7.3 ADQL schema (*and* any 
>>dependent schemas such as 'region'), the ADQL -> SQL translation sheets 
>>and the 0.7.3 SkyNode WSDL to the same area of ivoa.net as the pdfs, and 
>>suitably namespaced.  These after all define the standard(s) alongside 
>>the documents.
> 
> 
> I want to inject some caution into this request.
> 
> Some time ago, I asked that the ADQL schema adopt the our current 
> convention for IVOA schemas:
> 
>    http://www.ivoa.net/xml/ADQL/v0.7.4
> 
> The motivation behind my request was primarily to establish a 
> stable, predictable pattern for the namespace.  In the early development, 
> the namespace was changing quite a bit, reaking havoc on our application 
> work.  
> 
> Choosing a namespace can be tricky.  When it changes, applications break,
> so we can't be too cavalier.  With VOResource, we take advantage of the
> standard, optional convention to have the namespace URI resolve to the
> actual XSD document.  However, the current URI convention was chosen to
> favor its use as a URI, rather than its location on the IVOA site.  That
> means that we kept the URI fairly short and not reflective of the IVOA
> filesystem.
> 
> (Note that we didn't post the schemas at the http://www.ivoa.net/xml/ 
> location until we had official WD releases.  Thus, in the pre-release 
> stage, you cannot resolve the namespace URI to the schema.)
> 
> On the other hand, the URLs for the standard (prose) documents favor 
> humans locating them via a browser.  Thus, schemas and their related 
> standard documents are not together under a common directory.  This was 
> not expected to be a problem since we can provide links to both on a 
> single page.  
> 
> My suggestion is:
>   o  keep the current conventions for standard documents and XML schemas
>   o  be sure the ADQL standard document includes a link to the proper 
>      location of the schema.  This will be a location on the Twiki until 
>      the official WD release; then it is changed to the official release 
>      location.  
>   o  Ask to the document coordinator (Marco) to allow links to associated 
>      schemas to be appear on the document download page. 
> 
> cheers,
> Ray
>