OPeNDAP/THREDDS Directory Views

[Nathan Potter]

Jerry,

I was working on the server and I realized that the OPeNDAP directory  
view is customizable to a certain extent. It relies on a CSS file in  
the the docs directory. If you copy the default docs directory from  
$CATALINA_HOME/webapps/opendap/docs to the persistent content  
directory ($CATALINA_HOME/content/opendap/docs) you can safely modify  
the contents.css file and replace the logo.gif file with your own  
image. This should give you a modicum of control over the look and feel.


Nathan




On Apr 13, 2007, at 7:29 AM, Pan, Jerry Yun wrote:

> This was a question in my mind for a while too, so I am jumping on  
> this one.
>
> My suggestion is this: the data providers maybe better off having  
> the freedom on this interface themselves.  I think it would be  
> great if I could chose (1) leave it as it is, a default template,   
> (2) OLFS only (but with information how to get the catlog xml),   
> (3) use thredss interface only, or (4) custom the interface freely,  
> arange positions, layout, add/delete additional contents.  It would  
> be nice if I could customize all the pages.
>
> If we don't use servelet to spit out the htmp and instead use JSPs,  
> this desiered behavior may be easy to achieve.  There are also  
> frameworks like Struts or Java Server Face could help on this.
>
> Thanks.
>
> -Jerry
>
>
>
> -----Original Message-----
> From: owner-opendap-tech at unidata.ucar.edu [mailto:owner-opendap- 
> tech at unidata.ucar.edu] On Behalf Of Nathan Potter
> Sent: Thursday, April 12, 2007 5:52 PM
> To: James Gallagher; Daniel Holloway; OPeNDAP Tech
> Cc: Nathan Potter; John Caron; Ethan Davis
> Subject: OPeNDAP/THREDDS Directory Views
>
>
> Greetings,
>
> I would like to get some feedback about one of the OPeNDAP "services"
> and some possible changes to (or elimination/replacement of) the  
> service.
>
> OPeNDAP Directory/Contents
>
> OPeNDAP servers offer a "presentation view" of each collection of  
> datasets on the server. Typically this has been accessed by using a  
> browser to open a URL ending in "/". The OPeNDAP sever returns an  
> HTML document that the browser renders in human readable form.  In  
> server 3 this view was generated by the Apache web server.
>
> Server 3 example: http://test.opendap.org/opendap-3.7/nph-dods/data/ 
> nc/
>
> With Hyrax we have integrated THREDDS catalogs into our server.
> THREDDS has it's own presentation view which is different from the  
> OPeNDAP presentation view.
>
> Hyrax OPeNDAP presentation view: http://test.opendap.org:8080/opendap/
> data/nc/contents.html
> Hyrax THREDDS presentation view: http://test.opendap.org:8080/opendap/
> data/nc/catalog.html
>
>
> Unfortunately this is already creating problems:
>
> 1) The THREDDS view may contain additional datasets that are not  
> visible in the OPeNDAP view. (Data providers may add datasets to  
> the catalog that are not associated with data served by the BES)
>
> 2) If the THREDDS catalog.xml doesn't contain a datasetScan element  
> for each of the datasets/directories at the top level of the server  
> then the omitted ones will not appear in the THREDDS view (and  
> catalog). This means that the OPeNDAP view may include datasets  
> that the THREDDS view does not.
>
> 3) The OPeNDAP view differentiates between files that the server  
> recognizes as data and ones it does not. The dataset links in the  
> OPeNDAP view lead to the HTML data request form for data, and will  
> simply return the contents of the file if the server doesn't  
> recognize it as a dataset that it can handle. The THREDDS view is  
> built using the assumption that everything returned in a  
> datasetScan is data. So - THREDDS views don't really have a way to  
> include README files - they show up as a dataset and drilling down  
> leads to broken links and not to access to the file.
>
>
> - I can fix (1).
>
> - Fixing (2) is really a configuration problem that has to be  
> solved by each data provider.
>
> - Fixing (3) is much harder, and begs the question: Why support 2  
> views at all?
>
>
>
> ** OPTION 1 **
> Drop the OPeNDAP presentation view. If we can live with just the  
> THREDDS view then I don't need to fix (1). Problem (2) will be  
> addressed more readily by data providers because the THREDDS  
> catalog will need to be correctly configured for the server to  
> produce THREDDS catalogs and views. The draw back to this is that  
> we would loose the ability to serve "flat files" - README,  
> index.html, info.html, images, etc.
>
>
> ** OPTION 2 **
> Fix (1) and live with (2) and (3), broken links and all.
>
>
> ** OPTION 3 **
> Work with the THREDDS group and woo them to the idea that (3) is a  
> problem and that the THREDDS API's (and catalogs?) need to modified  
> to solve (3). I suspect we could do it by adding a different  
> "service" for the flat files. The CrawlableDataset interface would  
> have to modified so that it could be used to identify which files  
> were to be served using which service. When the datasetScan  
> elements are accessed the catalog get built with the serviceName  
> pointing to the OPeNDAP service for data, to the file service for  
> files that are not data... But I am speculating as I haven't spoken  
> our esteemed THREDDS colleagues.
>
>
>
> What do people think?
>
> Is OPTION 1 viable?
>
> Other ideas/options/thoughts/opinions?
>
>
> Nathan
>
>
>
>
> = 
> Nathan Potter                        ndp at opendap.org
> OPeNDAP, Inc.                        541.752.1852
>
>

= 
Nathan Potter                        ndp at opendap.org
OPeNDAP, Inc.                        541.752.1852