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Re: THREDDS/DLESE Connections slides



----- Original Message -----
From: "Peter Cornillon" <address@hidden>
To: "John Caron" <address@hidden>
Cc: <address@hidden>
Sent: Friday, December 14, 2001 11:30 AM
Subject: Re: THREDDS/DLESE Connections slides


> Hi John,
>
> An interesting presentation. I have a couple of comments.
>
> 1) Slide 6 you say that there is no efficient way to discover data sets
within
> the system.  First, I think that you should be careful to separate out
issues
> related to the data access protocol and other services. The DODS DAP does
> not provide an efficient way to locate data. That was not it's intent.
There
> are however sites that are beginning to provide for this. For example, the
> GCMD lists a subset of DODS accessible data sets (~2/3 of the total) and
> one can use any of the GCMD search mechanisms to locate a data set of
> interest. Furthermore, Dan Holloway has developed a Java program that
> will do this search as well as searches in other directories as they come
> on line. The important point here is that this search capability can be
> launched from within a user's application; e.g., from within Matlab and
> through the suite of associated interfaces can drill down to the data
> themselves and request that they be moved into the application. This
> capability is currently under developement with the search portion in
> beta.

Yes, services can be built that allow data discovery with DODS servers, but
they seem to need to know some info specific to the server (eg root URL
directories). As far as I know its impossible to write a data discovery
service that would work for any DODS server, without having some extra
information specific to each server.

The situation with ADDE servers is somewhat different. You can (more or
less) query the server to find out whats available, but this collection of
information takes a while (eg 8 minutes for complete image data on unidata's
ADDE server), too long for interactive (eg MetApp) access.

In both cases the role of THREDDS might be the middleware that does data
discovery on the servers to provide fast responses to the clients.

I am looking forward to hearing more about data search and discovery at the
developers meeting. We hope to corner Dan and see how his work might relate
to THREDDS catalogs, and if we can merge our efforts in some way.

>
> 2) I could find very little information on APPE. Do you have a URL for a
> site where it is described?

Its ADDE (Abstract Data Distribution Environment, I think). Hopefully Tom
Yoksas or Tom Whittaker can provide a good URL.

>
> It might also be of interest to the group that the DODS effort will be
funded
> to look at a SOAP implementation associated with the core. This is a
> prototype effort and should be complete within a year.

That will be interesting.

Thanks for your comments.



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