UN Science Workshop in Tokyo, June, 2007

[Frederic V. Hessman]

> I'll take another look at CDF, but the web page (http:// 
> cdf.gsfc.nasa.gov) reminds one of the opaqueness of the standard -  
> it practically smacks you in the nose with its statement that the  
> format is defined through a library implementation.  This is almost  
> the opposite of an XML standard like VOEvent, and is one reason  
> that astronomers remain wedded to FITS, a standard defined through  
> the refereed literature.

Well, whether a "library implementation" is a good thing or not  
depends upon who you are talking to.  I also flew over the CDF  
homepage and assumed they were talking with end-users, not  
infrastructure builders.   On the other hand, I didn't see any API  
links......

> I was not trying to suggest that VOEvent stick its nose in other  
> people's bidness, and I'm also not sure that was the point Rick was  
> trying to make.

... more or less, but Rob always has a classier way of saying it ;-)

>   Of all the VO protocols, VOEvent is the most egalitarian.  We  
> rely on STC, on tables, on URIs, on UCDs, on RTML, etc. and so  
> forth.  There is no reason a VOEvent packet might not reference a  
> CDF file.  A VOEvent packet is a publication relying on several  
> underlying standards.  The publish/subscribe paradigm is  
> specifically a way to gather data/metadata/information from diverse  
> sources for distribution to an interoperating set of applications  
> supporting one or more common communities.  A CDF file has no  
> inherent notion of citations, for instance.

Actually, the "reliance" on RTML is a very good example: "lots" in  
intended functionality and hints about all the great things we might  
do but in formal actuality "none".   The RTML tagability could just  
as easily have been CDF or some other format for some other  
purpose.   As Rob says, this is a strength, though perhaps one which  
hasn't been flexed enough.

> It is often better to adopt a pre-existing standard than to attempt  
> to supplant it.  As I said, VOEvent has been more open to this than  
> most VO technologies.  There was immediate consensus to adopt  
> RTML.  STC generated a lot of chatter - but really, there was no  
> alternative available.  Folks may or may not like the <Params>, but  
> we never sought to do anything other than adopt VOTable or raw XML  
> technology for the purpose.  The discussions regarding UCDs have  
> been raucous, but as long as namespaces are permitted by the  
> standard, I suspect we'll attempt to make this work for VOEvent, too.

One of my favorite topics which should now be coming up for major  
discussions in June.   As long as the meaning of <Param> contents and  
such remain hidden, it will be difficult to cash in on VOEvent's  
possibilities.

Rick

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Dr. Frederic V. Hessman     Hessman at Astro.physik.Uni-Goettingen.DE
Institut für Astrophysik          Tel.  +49-551-39-5052
Friedrich-Hund-Platz 1         Fax +49-551-39-5043
37077 Goettingen                 Room F04-133
http://www.Astro.physik.Uni-Goettingen.de/~hessman
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MONET: a MOnitoring NEtwork of Telescopes
http://monet.Uni-Goettingen.de
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