[CITE-Forum] Self join without aliases: valid?

Andrea Aime andrea.aime at geo-solutions.it
Wed Mar 21 09:31:04 EDT 2018


Hi,
the CITE test engine is generating the following request:

<?xml version="1.0"?><wfs:GetFeature
xmlns:wfs="http://www.opengis.net/wfs/2.0" count="10" service="WFS"
startIndex="0" version="2.0.0">
  <wfs:Query xmlns:ns50="http://cite.opengeospatial.org/gmlsf"
typeNames="ns50:PrimitiveGeoFeature ns50:PrimitiveGeoFeature">
    <Filter xmlns="http://www.opengis.net/fes/2.0">
      <Intersects>
        <ValueReference>ns50:PrimitiveGeoFeature/ns50:surfaceProperty</ValueReference>
        <ValueReference>ns50:PrimitiveGeoFeature/ns50:curveProperty</ValueReference>
      </Intersects>
    </Filter>
  </wfs:Query></wfs:GetFeature>


Now, as you can see, it's a self join, but does not contain any alias
declaration. As stated, software could be (imho) legitimately
think it's not actually a join, and that the two fiters are both referring
to the first "instance" of the feature type.

I've checked the specification, all self join examples use aliases, but I
do not see a clear request to use aliases on self-join.
Referencing a significant bit (from 7.9.2.4.2 "query the feature types
aliases parameter"):

Aliases are typically used in query expressions, that perform a join
operation (see 7.9.2.5.3), to support self-
joins. That is a join of one feature type back to itself.

EXAMPLE
typeNames="myns:Feat1 myns:Feat1" aliases="a b"

In this example, the first feature type, myns:Feat1, is aliased to the name
"a" and the second feature type, myns:Feat1, is
aliased to the name "b". Thus properties from the first instance of
myns:Feat1 can be referenced in a request as
"/a/property_name" and properties from the second instance of myns:Feat1
can be referenced in a request as
"/b/property_name" where the token "property_name" is used as a place
holder for the name of any property of the feature
myns:Feat1.


So... can anybody clarifiy if this is an issue in the test engine, or if
the servers are indeed supposed to understand
the above request?

Cheers
Andrea

==
GeoServer Professional Services from the experts! Visit http://goo.gl/it488V
for more information.
==

Ing. Andrea Aime
@geowolf
Technical Lead

GeoSolutions S.A.S.
Via di Montramito 3/A
55054  Massarosa (LU)
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39  339 8844549

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

AVVERTENZE AI SENSI DEL D.Lgs. 196/2003

Le informazioni contenute in questo messaggio di posta elettronica e/o
nel/i file/s allegato/i sono da considerarsi strettamente riservate. Il
loro utilizzo è consentito esclusivamente al destinatario del messaggio,
per le finalità indicate nel messaggio stesso. Qualora riceviate questo
messaggio senza esserne il destinatario, Vi preghiamo cortesemente di
darcene notizia via e-mail e di procedere alla distruzione del messaggio
stesso, cancellandolo dal Vostro sistema. Conservare il messaggio stesso,
divulgarlo anche in parte, distribuirlo ad altri soggetti, copiarlo, od
utilizzarlo per finalità diverse, costituisce comportamento contrario ai
principi dettati dal D.Lgs. 196/2003.

The information in this message and/or attachments, is intended solely for
the attention and use of the named addressee(s) and may be confidential or
proprietary in nature or covered by the provisions of privacy act
(Legislative Decree June, 30 2003, no.196 - Italy's New Data Protection
Code).Any use not in accord with its purpose, any disclosure, reproduction,
copying, distribution, or either dissemination, either whole or partial, is
strictly forbidden except previous formal approval of the named
addressee(s). If you are not the intended recipient, please contact
immediately the sender by telephone, fax or e-mail and delete the
information in this message that has been received in error. The sender
does not give any warranty or accept liability as the content, accuracy or
completeness of sent messages and accepts no responsibility  for changes
made after they were sent or for other risks which arise as a result of
e-mail transmission, viruses, etc.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengeospatial.org/pipermail/cite-forum/attachments/20180321/f3314059/attachment-0001.html>


More information about the CITE-Forum mailing list