[ckan-discuss] How is publicdata.eu website powered

[Adrià Mercader]

As Friedrich and David pointed out, you pretty much choose what to put
in the package fields (extras).
The ckanext-spatial [1] extension uses bounding box information stored
on the package extras and stores it on a PostGIS enabled table.
You can later perform a simple bounding box API query like:

/api/2/search/package/geo?bbox={minx,miny,maxx,maxy}[&crs={srid}]

to get the packages that intersect.

Do let me know if you are interested in this.


Adrià

[1] https://bitbucket.org/okfn/ckanext-spatial


2011/5/17 David Read <david.read at okfn.org>:
> Medhi,
>
>> unfortunately the attributes that I am looking for such as
>> the places (spatial) seem to be missing.
>
> The fields in CKAN are flexible. For example, some people have used
> their CKAN instances to describe the location of the data by country,
> by administrative area, and by lat/long polygon.
>
> Searching by the field is the trickier side of things and requires
> something beyond the basic search in core CKAN. We have the beginnings
> of rather advanced PostGIS solution. Do ask Adria if that interests
> you.
>
> David
>
> On 16 May 2011 22:34, Mehdi El Fadil <mehdi.elfadil at mango-is.com> wrote:
>> Hi Friedrich,
>>
>> Thanks for your answers.
>>
>> ckan.net and its api looks to be more usable to me to directly get data in
>> json format, but unfortunately the attributes that I am looking for such as
>> the places (spatial) seem to be missing.
>>
>> What I am looking forward to create is an alternative web UI. In case
>> neither the reduced json or solr results are directly fetchable, then I
>> should manage to extract data from n3 format.
>>
>> Thanks again,
>>
>> mehdi
>>
>> On Mon, May 16, 2011 at 5:58 PM, Friedrich Lindenberg
>> <friedrich.lindenberg at okfn.org> wrote:
>>>
>>> Hi Mehdi,
>>>
>>> On Mon, May 16, 2011 at 4:59 PM, Mehdi El Fadil
>>> <mehdi.elfadil at mango-is.com> wrote:
>>>>
>>>> I am currently studying options for an open data catalog project, and
>>>> would be interested in re-using some of the data from http://publicdata.eu
>>>> website.
>>>
>>> To clarify: publicdata.eu was a four-day development spike to evaluate the
>>> feasibility of data catalogue harvesting. While its a nice demo, we will
>>> soon merge it into CKAN which now has similar data harvesting capabilities.
>>>
>>>>
>>>> I have noticed the "data" link at the bottom of the site, and also the
>>>> code at bitbucket. I am not so familiar with semantic web, and I am
>>>> wondering whether opendata.eu is powered by on-the-fly parsing of the n3
>>>> files by some search engine, or whether there exists a database storing each
>>>> site according to place, creator and file type. Also, are the data only
>>>> available under n3 format, or is it possible to extract it in any other
>>>> format (json, csv ..)?
>>>
>>> publicdata.eu in its current form consists of two stages: data catalogues
>>> are harvested (scraped, often enough) and written out to n3 RDF at the
>>> "data" location. These files are then read by an indexer which flattens them
>>> into something like a reduced JSON form and sends them to Solr for indexing.
>>> The web UI is then only a thin layer around functionality offered by solr.
>>> Once moved to solr, the basic setup will remain very similar but we'll
>>> have management services for the harvesters and the intermediary phase will
>>> be the CKAN database - which can then be exported to RDF or JSON.
>>> Hope this helps?
>>> - Friedrich
>>
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