[Geoserver-devel] WFS 2.0 can return a numberMatched that violates the WFS 2.0 schema

GeoServer GeoServer Developer
1

Hi,
I’m working on http://jira.codehaus.org/browse/GEOS-6187 and as part
of it I’ve noticed that we are sometimes returning -1 as numberMatched.

Now, this is happening in situations in which we legitimately know the actual numberMatched,
so it’s a bug on its own, but, generally speaking, we might be in a situation where we don’t
know numberMatched at all:

  • we are using app-schema, that cannot do counts
  • we are using a complex filter in which part of the filter cannot be encoded in SQL (e.g., using
    filter functions), or we are working against a shapefile and we have an attribute filter, in both
    cases featureSource.getCount(…) will return -1 to state “sorry, too hard to compute”

However the spec defines the numberMatched type as follows:

<xsd:simpleType name=“nonNegativeIntegerOrUnknown”>
xsd:union
xsd:simpleType
<xsd:restriction base=“xsd:string”>
<xsd:enumeration value=“unknown”/>
</xsd:restriction>
</xsd:simpleType>
xsd:simpleType
<xsd:restriction base=“xsd:nonNegativeInteger”/>
</xsd:simpleType>
</xsd:union>
</xsd:simpleType>

So, in this case, we should be generating “unknown” as the output, not -1.
As far as I can see the WFS 2.0 FeatureCollectionTypeImpl takes this into account and
defines numberMatched to be “Object”, but in gs-wfs FeatureCollectionResponse
has:

public abstract BigInteger getTotalNumberOfFeatures();
public abstract void setTotalNumberOfFeatures(BigInteger n);

Now, I see a couple ways to amend this:

  • change totalNumberOfFeatures to be Object too, and set it to “unknown” in case
    we have a -1
  • change the feature collection binding to make an exception for numberMatched,
    and if it’s null or a negative number, return “unknown” instead

Do you have a preference?

Cheers
Andrea

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2

On Wed, Feb 26, 2014 at 7:12 PM, Andrea Aime
<andrea.aime@anonymised.com>wrote:

Now, I see a couple ways to amend this:
* change totalNumberOfFeatures to be Object too, and set it to "unknown"
in case
  we have a -1
* change the feature collection binding to make an exception for
numberMatched,
  and if it's null or a negative number, return "unknown" instead

In the end I went for the second approach:
https://github.com/geotools/geotools/commit/bb67ae0d41c1143d8f70bbc56c728c9b0c488e84

Cheers
Andrea

--
== Our support, Your Success! Visit http://opensdi.geo-solutions.it for
more information ==

Ing. Andrea Aime
@geowolf
Technical Lead

GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39 339 8844549

http://www.geo-solutions.it
http://twitter.com/geosolutions_it

-------------------------------------------------------

3

Apologies for not getting a chance to chime in on this one, been swamped with a deliverable. Was going to review on the weekend but looked at what you committed and the approach looks fine to me.

···

On Fri, Feb 28, 2014 at 6:38 AM, Andrea Aime <andrea.aime@anonymised.com> wrote:

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Justin Deoliveira
Vice President, Engineering | Boundless
jdeolive@anonymised.com
@j_deolive

On Wed, Feb 26, 2014 at 7:12 PM, Andrea Aime <andrea.aime@anonymised.com> wrote:

Now, I see a couple ways to amend this:

  • change totalNumberOfFeatures to be Object too, and set it to “unknown” in case
    we have a -1
  • change the feature collection binding to make an exception for numberMatched,
    and if it’s null or a negative number, return “unknown” instead

In the end I went for the second approach:
https://github.com/geotools/geotools/commit/bb67ae0d41c1143d8f70bbc56c728c9b0c488e84

Cheers

Andrea

–

== Our support, Your Success! Visit http://opensdi.geo-solutions.it for more information ==

Ing. Andrea Aime

@geowolf
Technical Lead

GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39 339 8844549

http://www.geo-solutions.it
http://twitter.com/geosolutions_it