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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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--=======AVGMAIL-4563271813F2====== Content-Type: multipart/alternative; boundary="=====================_2997680==.ALT"; x-avg-checked=avg-ok-67BB5B51 --=====================_2997680==.ALT Content-Type: text/plain; charset=us-ascii; format=flowed; x-avg-checked=avg-ok-67BB5B51 Hi Ben, Thank you for the useful note. >I think I may need to clarify the situation. The current primary >focus of the CSW/THREDDS gateway that GMU is working on is mainly on >mapping THREDDS catalog metadata to ISO 19115 so that THREDDS >metadata can be made available in an international standard >form. It would be a mistake to divert that project from it's high >priority objectives. I agree with you: this is a useful objective. Indeed, in the framework of GALEON phase II, we're interested in providing a contribution on such topic. In fact, we developed a mapping from THREDDS data model to an ISO 19115 profile. Presently, we're testing a similar mapping for CS-W.ebRIM, too. >On the other hand, the question of how to provide inventory catalogs >of "collections" of datasets, and catalogs of those collections -- >as THREDDS does -- keeps coming up in many different settings. It >arose in the OGC GALEON interoperability experiment; it came up in >discussions at the 3rd Interoperability Workshop on the Automated >Harvesting of Data and Metadata last week. In our opinion, this is another important issue. For example, we are experimenting a Web Service to aggregate distributed THREDDS catalogs, creating a new virtual catalog, using either a pull or a push based approach. ---Stefano >So I sent the message to the THREDDS and GALEON email lists in order >to get a wider group thinking about the issue which I think is a key >to making all these data services work together. For those of you >who are not familiar with THREDDS catalogs, an example of a >heirarchical set of catalogs is available for a variety of real-time data at: > > ><http://motherlode.ucar.edu:8080/thredds/catalog.html>http://motherlode.ucar.edu:8080/thredds/catalog.html > >As you will note as you drill down through the collections, you can >get the underlying xml representation of any of any of these >catalogs by replacing the .html with .xml in the URL. > > From Ron Lake's notes, it sounds like CSW.ebRIM can be used to > provide this type of functionality via a standards-based interface. >It's important though that, while we consider the long range goals, >we also retain realistic expectations of the current project. > >I hope this clarifies rather than confuses the issue. > >-- Ben > >On 11/18/06, Ron Lake ><<mailto:rlake@xxxxxxxxxxxxx>rlake@xxxxxxxxxxxxx > wrote: > >Hi, > > > >When this group says CSW, I assume you mean CSW.ebRIM? > > >Ron > > > >---------- >From: ><mailto:owner-galeon@xxxxxxxxxxxxxxxx>owner-galeon@xxxxxxxxxxxxxxxx >[mailto: owner-galeon@xxxxxxxxxxxxxxxx] On Behalf Of Ben Domenico >Sent: November 18, 2006 1:44 PM >To: Wenli Yang >Cc: Yonsook Enloe; Liping Di; ><mailto:access-geoscience@xxxxxxxxxxxxxx>access-geoscience@xxxxxxxxxxxxxx; >THREDDS community; Unidata GALEON; John Helly >Subject: Re: CSW, THREDDS, GALEON 2 > > > >Wenli, > > > >This issue of "granularity" or heirarchies or collections or >groupings of datasets that are alike in some way was one of the >issues confronted early in the THREDDS project. As a result, I >believe we have an approach that works reasonably well in the >THREDDS Data Server package. The issue continues to arise in most >discussions of data and metadata collections and services. In fact >it was one of the issues discussed at the 3rd Metadata >Interoperability Conference I attended last week. It will be >important to confront it in the context of OGC and ISO >standards. The disadvantage of doing it in the WCS context is that >one can envision collections that might include Coverages, Features, >and Sensor Observations. For example a collection of all the data >related to a specific event such as a severe storm, a flood, a >hurricane, and so forth. One can create THREDDS catlogs for such >"case studies." But it would be good to eventually have a >standards-based interface for such collections. Perhaps the OGC CSW >is not well suited to this sort of use at present. If so, it may be >useful to consider suggesting augmentations to CSW. I believe there >is a big advantage in that we already have a working system. > > > >I plan to send a copy of this to the THREDDS and GALEON groups as >well as to John Helly who convened the Interoperability Workshop last week. > > > >Thanks for your careful description of the issues in terms of >THREDDS catalogs and OGC CSW.. > > > >-- Ben > > > >On 11/15/06, Wenli Yang ><<mailto:yang@xxxxxxxxxxxxxxxxxxxxxxx>yang@xxxxxxxxxxxxxxxxxxxxxxx> wrote: > >Ben, > >THREDDS deals with service/data hierarchy nicely. However, I think >that CSW does not provide guidance/standard on how hierarchical >service/data should be presented. When mapping a THREDDS catalog >into our CSW, we can track and record the hierarchical relationships >among data/catalogReferences and among different levels of catalog >references in our database. We haven't fully investigated how such >relationships can be presented to a CSW client (or how a CSW client >can request such relationships). This is certainly a very useful >piece of information and deserve further discussion. > >I have not carefully read the WCS hierarchical description part >which was primarily provided by Luc. I think that the primary >intention of using hierarchical description in WCS capability was >not to let a client actually retrieve this the hierarchy information >but was to reduce the duplication of metadata in, and thus the size >of, the capabilities document. Initially, it was hoped that the >hierarchical information would allow a client to retrieve a >collection of data sets (coverages) from a higher node in the >hierarchy but it was decided that this would not be specified. Of >course, a specific server implementation can still provide such >capability by declaring a collection of coverages as one single >virtual coverage. For example, a THREDDS service reference >containing a time series collection of data sets (individual >coverages) for a specific location can be declared as one coverage >with a time span covering all the data sets. In addition, each of >the data sets in the collection can, if needed, also be separately >declared as a coverage with time range being at a point time (or a >smaller time range as compared to that of the collection). > >Wenli > >At 19:04 2006-11-12 -0500, Yonsook Enloe wrote: > > >Ben, > > > >This is an important topic. Lets discuss sometime. The next >access-geoscience telecon is scheduled for Dec 20 th. We could >schedule one earlier to just discuss thoughts and ideas on >this&..What do you think? > > > > >Yonsook > > > > > > > >-----Original Message----- >From: Ben Domenico [ ><mailto:bendomenico@xxxxxxxxx>mailto:bendomenico@xxxxxxxxx] >Sent: Tuesday, November 07, 2006 11:19 AM >To: Liping Di; Wenli Yang; Yonsook Enloe >Subject: CSW, THREDDS, GALEON 2 > > > >Hi all, > >You are probably already aware that I think the CSW interface to >THREDDS catalogs is a key element of GALEON Phase 2. Our experience >it Phase 1 inidicated that -- at least for the WCS installations >used for that interoperability experiment, the WCS GetCapabilities >request was inadequate to provide the information available in the >hierarchical THREDDS catalogs at sites such as: > > ><http://motherlode.ucar.edu:8080/thredds/idd/models.html>http://motherlode.ucar.edu:8080/thredds/idd/models.html > http://lead4.unidata.ucar.edu:8080/thredds/catalog/ > ><http://nomads.ncdc.noaa.gov:8085/thredds/catalog/>http://nomads.ncdc.noaa.gov:8085/thredds/catalog/ > > > >I want to introduce these issues to the GALEON team, but I am very >much interested in your thoughts on whether and how the ACCESS >CSW/THREDDS work should into the GALEON Phase 2 initiative. Please >give me your input on this topic. > >I have been holding off on moving forward with Phase 2 until the WCS >1.1 specification is adopted near the end of the year. But perhaps >we could keep the GALEON embers burning in the meantime with a >discussion of CSW issues. > >I am convinced this is among the most important areas for standards >evolution. Please let me know what you think. > >Thanks in advance. > >-- Ben > > > > > > > > >No virus found in this incoming message. >Checked by AVG Free Edition. >Version: 7.5.430 / Virus Database: 268.14.6/536 - Release Date: >16/11/2006 15.51 --=====================_2997680==.ALT --=======AVGMAIL-4563271813F2====== Content-Type: text/plain; x-avg=cert; charset=us-ascii; x-avg-checked=avg-ok-67BB5B51 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Content-Description: "AVG certification" No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.430 / Virus Database: 268.14.6/536 - Release Date: 16/11/2006 1 5.51
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