[SDMX] List of all values of a categorical variable in WFS

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

[SDMX] List of all values of a categorical variable in WFS

lmorandini
Folks,

I am developing a datastore for SDMX data sources (clearly, a geometryless one).
It kind of works, with CQL/XML filters used to bind the dimensions to values and
choose the one measure to return.

However, I don't really know how to return the list of members of a dimension,
list which is necessary to build the filter.

For instance, before selecting all the male resident population of a certain
country, I need to know the members of the "Gender" dimension, the list of all
measures available, and the members of the "Country" dimension as well.

One (lame) way could be to add ancillary feature types, to be queried before
querying the "real" data.

Say we have a "Population" store (SDMX), then the following feature types would
be added automatically:
- Population_Cube (Cube itself)
- Population_Cube_Gender (Ancillary feature type containing the members of the
Gender dimensions, say: "M", "Male"; "F", "Female")
- Population_Cube_Mesure (Ancillary feature type containing the measures, say:
"1", "Resident population"; "2", "Total population")
- Population_Cube_Country (Ancillary feature type containing the members of the
Country dimensions, say: "AL", "Albania"; "AU", "Australia" , ...)

Any better idea?

Cheers,
Luca Morandini
Data Architect - AURIN project
Melbourne eResearch Group
Department of Computing and Information Systems
Room 3.08, Level 3, Doug McDonell Building, Parkville Campus
University of Melbourne
Tel. +61 03 903 58 380
Skype: lmorandini
LinkedIn: https://www.linkedin.com/in/lmorandini


------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
GeoTools-GT2-Users mailing list
[hidden email]
https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
Reply | Threaded
Open this post in threaded view
|

Re: [SDMX] List of all values of a categorical variable in WFS

geowolf
On Tue, May 23, 2017 at 3:00 AM, Luca Morandini <[hidden email]> wrote:
Folks,

I am developing a datastore for SDMX data sources (clearly, a geometryless one).
It kind of works, with CQL/XML filters used to bind the dimensions to values and
choose the one measure to return.

However, I don't really know how to return the list of members of a dimension,
list which is necessary to build the filter.

For instance, before selecting all the male resident population of a certain
country, I need to know the members of the "Gender" dimension, the list of all
measures available, and the members of the "Country" dimension as well.

Code wise, this is normally done by running a feature visitor on a collection. Well known
feature visitors such as count and distinct are normally optimized away 
in the store and computed in a more efficient way (think "select distinct" in a relational
database).

However, WFS cannot expose those results, because an aggregation breaks the
XML schema of the results and there is no way to call aggregates to start with.
So that is normally exposed by WPS processes that do exactly that, check the
UniqueProcess in WPS (it actually runs a UniqueVisitor against the store,
and the store can optimize it).

If you want to use solely WFS, then exposing a side table seems indeed an option.

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


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.


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

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
GeoTools-GT2-Users mailing list
[hidden email]
https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users
Reply | Threaded
Open this post in threaded view
|

Re: [SDMX] List of all values of a categorical variable in WFS

lmorandini
On 23/05/17 18:10, Andrea Aime wrote:
>
> However, WFS cannot expose those results, because an aggregation breaks the
> XML schema of the results and there is no way to call aggregates to start with.
> So that is normally exposed by WPS processes that do exactly that, check the
> UniqueProcess in WPS (it actually runs a UniqueVisitor against the store,
> and the store can optimize it).

Thanks for the suggestion.


> If you want to use solely WFS, then exposing a side table seems indeed an option.

This looks like a more palatable option than WPS (at least for our users).

Thanks again for the quick reply,

Luca Morandini
Data Architect - AURIN project
Melbourne eResearch Group
Department of Computing and Information Systems
Room 3.08, Level 3, Doug McDonell Building, Parkville Campus
University of Melbourne
Tel. +61 03 903 58 380
Skype: lmorandini
LinkedIn: https://www.linkedin.com/in/lmorandini


------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
GeoTools-GT2-Users mailing list
[hidden email]
https://lists.sourceforge.net/lists/listinfo/geotools-gt2-users