too much complexity?

[Robert Hanisch]

----- Original Message ----- 
From: "Tony Linde" <ael at star.le.ac.uk>
To: "'Robert Hanisch'" <rjhanisch at worldnet.att.net>; <registry at ivoa.net>
Sent: Wednesday, September 17, 2003 6:30 AM
Subject: RE: too much complexity?


> Hi Bob,
>
> > throughout this project in urging folks to start simple,
> > implement, and see what we've missed or need to change rather
>
> Isn't that what we're doing. AstroGrid has implemented two different
> versions of RM in its last two iterations and will implement 0.9 (or 0.8
> plus schema 0.8.x) in the next one in time for the Jan demos.
Yes, but so far it is only AstroGrid and NVO.  I think we need to settle
soon on something the other projects are comfortable moving ahead with, too.

> > not understand, or not take the time to learn.  One maxim of
> > the VO is to keep the entry cost low.
>
> This is why I keep going on about making the schema flexible enough to be
> specific to certain types of resource and using astronomer-friendly entity
> names. People will not use a system which seems to have masses of
irrelevant
> information or naming they do not understand. Let's make it easy for the
> users, not the developers (within reason of course).

This is indeed the heart of the matter.  Sometimes I fear that too much
flexibility leaves both users and developers confused.  The user interface
for Adobe Illustrator, for example, provides access to hundreds of
sophisticated functions.  Someone new to the program (me) just looks at it
and says "huh?  Where do I start?"

I think it is also ambiguous just who the "developers" and "users" are for
the registry services.  Initially at least I think they will be
one-and-the-same, i.e., the data centers.  As the data centers are primarily
all partners in the various VO projects, we can expect them to help us flesh
out the metadata definitions and associated schema to some extent.  On the
other hand, if they see the system as complicated and confusing we risk
alienating them.

I still prefer direct alignment with DC unless we have a compelling reason
to be different.  Several years ago I worked closely with an IT specialist
(Archie Warnock -- some of you may know him) on some metadata design issues,
and he advocated using names for metadata elements that are totally
abstract -- X1, P2 -- so that arguments about the best label could be
avoided altogether.  (We've heard similar arguments about Identifers!)  I
think the point here is that the label is one thing, but the description
attached to it is more important.  We can store and transport metadata that
is maximally compliant to DC, but present interfaces to registries for
metadata entry that remove the ambiguity of any particular label.  Language
is imperfect, and no matter what label we pick its definition will be clear
to one and unclear to another, or worse, clear to person 1 (this means A)
and equally clear to person 2 (this means B).  Since there is very little in
DC that is astronomy-specific, I think there is little to be gained in
changing the labels and something to be lost in having to set up translation
tables in order to publish to DC metadata collections.

>
> > Following up this point briefly... I don't think the registry
> > metadata should even attempt to track citations TO a
>
> Agreed.
>
> > I think the registry should be able to handle each of the
> > catalogs.  If Resources are too coarse-grained we will have
>
> Agreed.
>
> > with huge surveys.  My experience in hand-entering Vizier
> > catalogs into the NVO prototype registry suggests that the
> > whole thing could be automated, e.g., by parsing the GLU
> > dictionary and creating a mapping to the Resource
>
> Yes, we're hoping to do this in AstroGrid iteration 04 and will be meeting
> with Francoise and Francois in Strasbourg to see if this is possible.
>
> Cheers,
> Tony.

Well, three things we agree on!  That's progress!

Cheers,
Bob