usage of ps_descriptions table in petascope 8.x

[damiano]

in table ps_descriptions "abstract" and "keywords" are not used

[abeccati]

Thanks for reporting Damiano.

From a quick look at WCS 2.0 and GMLCOV 1.0.1 specs I could not find reference to "keywords" hence I think this belongs to some other related standards, would you please provide where you expect these fields to be outputted to make this report self-contained so we can speed up its resolution by a community member?

Once this info is there I think the ticket can be considered "easy" to solve = good for newcomers.

[Piero Campalani]

I also searched through the schemas some time ago, and found no keywords to be associated to coverages.
They can however be set in the service capabilities by overwriting/editing the template in Petascope (petascope.wcs2.templates.ServiceIdentification.templ, eg with Tomcat in $CATALINA_BASE/webapps/petascope/WEB-INF/classes/petascope/wcs2/templates/). See also PetascopeUserGuide#Servicecapabilitiesmetadata .

However the table ps_description suggests these are per coverage.
Looking into the code I see these fields are only used in the updateMetadataWithDescription method in the wcst package:

$ grep updateMetadataWithDescription [...]/java/petascope/ -R
java/petascope/wcst/transaction/executeTransaction.java:    private CoverageMetadata updateMetadataWithDescription(CoverageMetadata meta, CoverageDescriptionType desc) throws WCPSException, WCSTException {
...

[Piero Campalani]

Corrige: description elements are possible in a CoverageSummary, however Petascope is not using them.
If you need them I suggest to participate in ​this discussion at some point.

[Piero Campalani]

They are actually allowed in the general ows:DescriptionType, which is extended by the wcs:CoverageDescriptionType.
​http://schemas.opengis.net/ows/2.0/owsDataIdentification.xsd

[Piero Campalani]

Patch is submitted.

Once accepted the content of the table ps_descriptions will not be ignored, and will fill in the correspondent OWS elements in the coverage descriptions.
One raw per coverage is admitted by database contraints, and I saw in the WCS 1.0.0 implementation that for keyword it was allowed a syntax to permit multiple keywords, see:

petascope.wcs.server.core.executeDescribeCoverage class which uses the str2String() method of the SDU class in the package petascope.wcps.server.core for the keywords:

...
if (string.startsWith("{") && string.contains(",") && string.endsWith("}")) {
...

This means that:

# SELECT * from ps_descriptions;
 id | coverage |    title     |    abstract     |    keywords     
----+----------+--------------+-----------------+-----------------
  1 |        1 | this title 1 | this abstract 1 | this keyword 1
(1 row)

will resolve to:

<wcs:CoverageDescription ...>
  <ows:Title>this title 1</ows:Title>
  <ows:Abstract>this abstract 1</ows:Abstract>
  <ows:Keywords>this keyword 1</ows:Keywords>
...

And this:

# SELECT * from ps_descriptions;
 id | coverage |    title     |    abstract     |     keywords     
----+----------+--------------+-----------------+------------------
  1 |        1 | this title 1 | this abstract 1 | {key1,key2,key3}
(1 row)

will resolve to :

<wcs:CoverageDescription ...>
  <ows:Title>this title 1</ows:Title>
  <ows:Abstract>this abstract 1</ows:Abstract>
  <ows:Keywords>key1</ows:Keywords>
  <ows:Keywords>key2</ows:Keywords>
  <ows:Keywords>key3</ows:Keywords>

If the same behavior is needed for multiple titles and abstracts, please just request it.

[Piero Campalani]

Fixed in changeset:b277588.

[Piero Campalani]

An important leak in the submitted patch breaks the WCS service when non mandatory fields like abstract and keywords are left blank.

Current Workaround: set those fields as empty strings, rather then letting them null.

[Dimitar Misev]

Not sure which version does that patch affect (as milestone is Future)?

[Piero Campalani]

This is on release_8.5 branch, and the leak occurs from v8.5.2 on. Patch upcoming.

[Piero Campalani]

What I said in comment:6 is wrong: wcs:CoverageDescriptionType does not extend ows:DescriptionType, but rather gml:AbstractFeature which does not include an ows:DescriptionType` element (the one for titles, abstracts and keywords).

This means that now the addition of title (+ abstracts or keywords) breaks the validity of the GML response.

This fragment:

  <ows:Title>this title 1</ows:Title>
  <ows:Abstract>this abstract 1</ows:Abstract>
  <ows:Keywords>key1</ows:Keywords>
  <ows:Keywords>key2</ows:Keywords>
  <ows:Keywords>key3</ows:Keywords>

taken from ps_descriptions should go in the coverage summaries of a GetCapabilities response.

In order to have a valid GML, currently it is better to drop the contents of ps_description.

[Piero Campalani]

Being the capabilities document always quite a hot topic, I will address the two issues in two different patches: one for the null pointer (ready for subhmission) and the second for moving those elements to the capabilities document (after discussion).

[Piero Campalani]

Null pointer error fixed in changeset:0e4b2e5.

[mantovani]

Having discussed with endusers, we need to move from DescribeCoverage to GetCapabilities this:
<ows:Title>this title 1</ows:Title>

<ows:Abstract>this abstract 1</ows:Abstract>
<ows:Keywords>key1</ows:Keywords>
<ows:Keywords>key2</ows:Keywords>
<ows:Keywords>key3</ows:Keywords>

[Piero Campalani]

This could be easily done, and should be done since we have this feature available.

From #314, we have now a parameter for enable/disable the OWS Metadata element in a capabilities document, we could change its purpose to switch for light/fat capabilities: light capabilities drops out OWS metadata and coverage descriptions (title/abstract/keywords).

[mantovani]

No objections from my side for this solution:

• light mode provides faster performance
• fat mode provides slower performance with detailed information

[mantovani]

any decision / step forward on this ticket?

[Piero Campalani]

It seems that configuration in petascope.properties is the way to go (see #735 also).
I'll patch the new params soon. !

[Piero Campalani]

(Configurable) coverage descriptions added to coverage summary in changeset:46aaa33.
An update of petascopedb is needed.

The patch is related to v9, not to v8.5 as this ticket, so I spawned #802 for it.

[Dimitar Misev]

Fixed in 9+, I don't think we'll do it in v8 though, so closing.