who is actively developing with VOResource?
kmb at mssl.ucl.ac.uk
Thu Nov 20 01:06:29 PST 2003
Hello Ray, sort of reposting a message I sent you earlier to the registry
Here at Astrogrid, I am heading up the Registry group to conform to the new
IVOA schema. For the most part the conforming to the schema has not been
much of a problem, but I will know more next week when I start implementing
a harvesting ability with Astrogrid. To be honest I have not been focusing
on what information is going into the schemas, just been focusing on
conforming to the new schema and the required elements/attributes I will
need. Their are a few issues/tasks that I can foresee happening, but again
I will know more next week. Here are those things.
1.) update attribute in Resource element - Currently the update attribute is
not a required attribute and I believe the update and created need to be a
required attribute (use="required"). For the Astrogrid development we will
most likely put these attributes in on all of our Resources. After
discussing a little with Wil this also seems to be a requirement for NVO as
well. The reason for this requirement is that the "update" attribute makes
a good spot for doing our harvesting based off of a current date/time. Also
makes things very good for tracking purposes of resources. May wish to
discuss if the "status" attribute is required I would propose yes as well.
a.) One other side note to this we may eventually wish to change from
xsd:date to a time based one. Not at this stage, but we will need to take
into account time zones later on for when other VO's come in (ex China,
Australia) and we wish to use this "updated" attribute for harvesting
otherwise we may not catch some data.
2.) Root elements - Still not sure why their are 2 root elements with only
difference is the minoccurs and maxoccurs, a VODescription (1-unbounded) and
a VOResource (1-1). Maybe it will come clear to me at a later stage. I am
thinking maybe when the schema was drawn up that maybe your trying to cover
all possibilities. But if you think about it in the client/implementation
perspective the majority of queries you will do will be Multiple (I think
:) ). Now if you do only expect 1 result and you get more, most clients
would probably show all the results or at least take the first one then
appropriately log some warning/error "Expected 1 result and got back 2 or
more". Also if you did get back more results than 1 then it is probably the
client/implementers problem of somehow having duplicate entries in the
registry or not having a specific enough query, but it is the implementation
fault. And lastly maybe I have not seen enough schemas yet, but 2 root
interchangeable root elements is something I don't normally see. For
Astrogrid purposes we will be able to handle VOResource if we receive it
from an external registry, but Astrogrid will only be returning back
VODescription elements. If this does come up for discussion I will pitch my
2 cents in for getting rid of both the root elements and make a new one
called VOResources (1-unbounded).
3.) Yeah I would agree Ray I think you might be right about describing
specific kinds of services, but not sure yet. Their was a 1 or 2 more
things to put down, but I will wait until I see how things go next week.
4.) Oh forgot final thing, something to take care of in later iteration. On
a few if not all of our simple type strings (xsd:string) such as Description
element it would be good to put a maxlength restriction to it, otherwise
eventually somebody might try to put a "War and Peace" book as a description
p.s. Curious if anybody has tried throwing all these IVOA schemas into a
WSDL. I will be trying it soon, but curious if anybody else tried it and
got it going? I have a feeling these substitutionGroup stuff will not work
and I will need to make some minor modifications such as combining schemas
and taking out substitutionGroup stuff, but I will cross that bridge when I
come ot it.
From: owner-registry at eso.org [mailto:owner-registry at eso.org]On Behalf Of
Sent: 18 November 2003 19:13
To: registry at ivoa.net
Subject: who is actively developing with VOResource?
I'd like to hear who is involved in using the VOResource metadata and how
things are going. I've been in intense communication with people here in
the NVO project, but I haven't heard too much from abroad. Could some
non-NVO people post a few words?
As my previous message indicated, issues are coming up that we will need
to deal with, and it would be good to hear about who is dealing with them
There are various issues that have come up in the NVO experience so far:
* The Coverage mark-up is a temporary stand-in, and it hasn't been well
reviewed and exercised. Is it sufficient?
o there was a suggestion that we alter it to allow
multiple, alternative spatial coverage descriptions where one in
the ICRS frame would be required.
* There remains a problem in VODataService-v0.4 with the use of a fixed
* There was a suggestion that there could be an easier/better way to
identify specific kinds of services (e.g. SIA) than with
the StandardID element.
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