[OSGeodata] geodata stylesheets

[Kralidis,Tom [Burlington]]

> -----Original Message-----
> From: Norman Barker [mailto:nbarker at ittvis.com] 
> Sent: 03 August, 2006 11:05 AM
> To: geodata at geodata.osgeo.org
> Subject: RE: [OSGeodata] geodata stylesheets
> 
> Thanks for the list, and the version numbers, if I get the 
> WCS retrieval fully working this way then the others will be 
> very similar.
> 

Check out the mapbuilder codebase.  They already have some XSLT's to
parse OGC:WMS and OGC:WFS, I believe.

> 
> The Sensor Observation Service would be interesting in terms 
> of generating GeoRSS, and there are a couple flying around at 
> the moment (MapServer has support).
> 

We're almost done deploying our OGC:SOS via MapServer of our national
water quality measurements.  As an asdie, we have to tweak the MapServer
code still for OGC:SOS, as, at this point, one station (sensor) is seen
as a LAYER object, which could be cumbersome for monitoring programs
with hundreds of stations (sorry, my gaffe on that one, this is how we
outlined the design when we funded OGC:SOS support in MapServer).
Anyways, better off discussed on mapserver-dev.

I think, for a catalogue, we'll also want to have OGC:SensorML documents
supported.  Conceptually, a SensorML document can be a catalogue
resource, which can point to an OGC:SOS, which can provide O&M, or
GeoRSS, etc.

> I have concerns about how much useful metadata you can 
> retrieve from a getcapabilities call, the time period is 
> important, and also since most getcapabilites are dynamic 
> should you just fetch every time - or say file size (as 
> determined by an http head request) is an indicator of 
> whether to fetch?
> 

I know the OGC:WMS 1.1.1 DTD has a root element attribute of
updateSequence (see section 7.1.3.4 of OGC:WMS 1.1.1 spec at:
http://portal.opengeospatial.org/files/?artifact_id=1081&version=1&forma
t=pdf).  The problem is that this is an optional element, so some
instances may not have this info.

>From my experience, harvesting frequency has been ad hoc thus far (i.e.
somehow figuring out things have changed, then harvest).  We could do an
HTTP HEAD as a means of quick scanning, but what happens if the filesize
is the same but the content has changed?  Mind you, chances of this
would probably be small.  I wonder what others have done for their
catalog updates.


> I have copied the concerning bits from the stylesheet here 
> but they relate to populating the database schema
> 
>     <!-- boolean ok for classifying type? -->
>     <entry key="raster">1</entry>
>     <entry key="vector">0</entry>
>     <entry key="point">0</entry>

How are you figuring this out from GetCapabilities?  For OGC:WFS, we
know it's vector, OGC:WCS raster.  For OGC:WMS, are you checking the
(again optional) Layer/@opaque attribute?

>     <!-- evaluate bbox, so not just to get -180,-90,180,90 from lazy
> admins-->
>     <xsl:call-template name="bbox">
>         <xsl:with-param name="list" select="//wcs:lonLatEnvelope"/>
>     </xsl:call-template>
>     
>     <!-- what value should we put in here? -->
>     <entry name="date"><xsl:value-of 
> select="date:date-time()"/></entry>
>     <!-- need to a describeCoverage here, but this could be 
> different for every coverage offering brief and we are only storing
> capabilities-->
>     <entry name="timePeriod"></entry>
>     <!-- CRS ref is forced to epsg:4326 -->
>     <entry name="projRef">EPSG:4326</entry>
>     <entry name="dataSource">WCS</entry>
> 

What is the underlying database schema you are populating to?



> 
> This is quite nice!
> 
> If we assume all of metadata will be encoded in XML, we 
> should probably
> list what XSLT's we need, a few off the top of my head:
> 
> OGC:WMS 1.1.1
> OGC:WFS 1.0.0
> OGC:WCS 1.0.0
> FGDC:CSDGM-1998
> ISO19115
> ISO19119
> OGC:OWSCommon
> GeoRSS
> 
> 
> Any others?
> 
> ..Tom
> 
> 
> > -----Original Message-----
> > From: Norman Barker [mailto:nbarker at ittvis.com] 
> > Sent: 03 August, 2006 10:44 AM
> > To: geodata at geodata.osgeo.org
> > Subject: [OSGeodata] geodata stylesheets
> > 
> > Hi,
> > 
> > Following on from our earlier discussions I wrote a 
> > stylesheet targeted towards extracting information from a 
> > getcapabilities response;
> > 
> > I have attached the test capabilities response (just a crude 
> > manufactured example), the stylesheet (you will need the 
> > exslt extensions for your language (java has them already, 
> > firefox will need the pure text versions), and the output (I 
> > have made this Java serializable specific - doesn't have to be).
> > 
> > I have put comments inline in <xsl:template 
> > match="wcs:Service"> in metadata_wcs_1.0.0.xsl, where I think 
> > we are missing info, or have questions.  From the 
> > capabilities we can't get time periods, and we struggle to 
> > get some meaningful data.
> > 
> > Please let me have your comments, I think I am going to go 
> > down the stylesheet route for extracting the data and then 
> > pulling it into Java and hence in the persistence model - if 
> > this isn't recommended please let me know.
> > 
> > Thanks,
> > 
> > Norman
> > 
>