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Re: documentation



Hi Ethan

On Thursday 05 January 2006 17:55, Ethan Davis wrote:
> Bjørge Solli wrote:
> >I'm using thredds 3.4 on tomcat 5.0.30.
> >
> >My content/thredds/catalog.xml contains:
> ><catalogRef xlink:title="North Atlantic Class 1 - Best estimate and
> > bulletins" xlink:href="dodsC/mersea-ip-class1-nat.xml">
> >     <documentation type="summary">
> >                   DODS Data Prepared for the MERSEA IP EU Project.
> >     </documentation>
> >     <documentation type="simple"
> >                   xlink:href="http://www.mersea.eu.org";
> >                   xlink:title="MERSEA Project Web page">
> >     </documentation>
> ></catalogRef>
> >
> >Where is the documentation shown?
>
> It really depends on what THREDDS client you are using. It sounds like
> you are viewing the catalogs in a browser in which case the TDS XML to
> HTML code can be thought of as the THREDDS client. In the TDS HTML
> catalogs, the documentation is only seen on datasets that have IDs (and
> are not catalogRefs, as those are links to the next level of catalog.
>
> The NetCDF-java ToolsUI client displays the metadata for whatever
> dataset is currently selected.

Thanks. This helps. I am myself not a user of the data, I'm just aiding the 
researchers, so I did not think of this.

> >Wouldn't it be better to have a <metadata inherited="true">...</metadata>
> >inside <catalogRef> and let all the datasets in
> >dodsC/mersea-ip-class1-nat.xml inherit them? Another way that would work
> > for me was to have it like this:
> ><dataset "container"> <!-- no ID on this -->
> ><metadata inherited="true">...</metadata>
> ><catalogRef ... />
> ></dataset>
> >And then all the datasets in the catalogRef also inherit the metadata.
>
> Unless the catalogRef and the referenced catalog are generated from
> datasetScan elements, the metadata in your top catalog will not be
> visible across the catalogRef link in the referenced catalog even if the
> metadata is declared inherited. Since each catalog can be referenced
> seperately, a catalog needs to stand alone. It can reference other
> catalogs and URLs but it can not depend on an upstream link that the
> user/client may not have followed. Here's how the spec puts it, "[t]he
> referenced catalog is not textually substituted into the containing
> catalog, but remains a self-contained object".
>
> Of course, you can put the metadata in the referenced catalog by hand so
> that it is inherited by all the contained datasets. Or you can have the
> catalog(s) generated from datasetScan elements and all the metadata for
> the datasetScan will be automatically included in the generated catalogs.

My catalogs are big and generated by a script. I'm looking into the 
possibility of using catalogScan, but at the moment this seems not practical. 
I will just have to make the script add the metadata as well.

> >I use catalogRef to avoid having to process all my large datasets unless
> >specifically asked for, but they mainly have pretty much the same
> ><authority>, <dataType>, <dataFormat>, <documentation>, <creator> and
> ><publisher>.
>
> Are you using datasetScan elements for automatic catalog generation in
> your content/thredds/catalog.xml? Or only at lower levels of you catalog
> tree. Using datasetScan elements would do a lot of this for you and the
> catalogs don't get generated until requested.
>
> We use catalogRef elements in our TDS configuration to split things
> apart that have very different metadata. And just to keep the pieces we
> need to maintain on a reasonable scale. The problem with using
> catalogRefs is that it often requires a bit of metadata duplication.
> 
> Hope this helps. Let me know if you have further questions.

Thanks. It helped.

-- 
Bjørge Solli - Office:+47 55205847 cellph.:+47 91614343
Nansen Environmental and Remote Sensing Center - Bergen, Norway
http://www.nersc.no Reception: +47 55205800
Dept.: Mohn-Sverdrup Center for Global Ocean Studies 
       and Operational Oceanography


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