[Geopackage] Historical question on metadata

Jeff Yutzler jeffy at imagemattersllc.com
Mon Jun 4 18:03:18 EDT 2018


Barry,
Unfortunately the Metadata extension has not been heavily used yet. This is
in the broad category of things that people insisted be part of GeoPackage
but that haven't gotten the expected uptake.

I currently only have two samples that exercise the extension and both of
them are fairly simple.

   - https://portal.opengeospatial.org/files/?artifact_id=74983
   - https://portal.opengeospatial.org/files/?artifact_id=74984

Both were produced by AGC.

In terms of how to document them, I'm pretty wide open. We produced
geopackage.org to be a place to put this stuff, but it is only as good as
the content people create. There is a short summary of how to use the
Metadata Extension here <http:///>,


On Mon, Jun 4, 2018 at 5:32 PM, Paul Daisey <pdaisey1331 at gmail.com> wrote:

> Barry:
>
>     Sorry, I don't have a sample GeoPackage that addresses the metadata
> issue.   I'm retired, no longer have work data on my laptop, and my archive
> DVDs are in the attic.  If you already have generated an XML metadata doc
> that validates according to ISO 19115 schemas, all you need do is insert it
> into a GPKG metadata table record column, with the mime_type column value
> "text/xml", a md_standard_uri column value pointing to the public 19115 XML
> Schema, and the md_scope column value set to the appropriate value,
> probably "dataset", assuming it applies to the entire GPKG.  If that is the
> case, then you also need a metadata_reference table record with a
> reference_scope column value of "geopackage" that refers to the metadata
> table record id column value in the md_file_id column, and with table_name,
> column_name, row_id_value and md_parent_id column values of NULL.
>
>     If you want to add additional metadata records (perhaps from another
> source?) that only apply to particular subsets of geopackage data, and that
> amend or supplement the record above, then the metadata_reference table
> records for those metadata documents should refer to the metadata table
> record id above in the md_parent_id column value, and the other column
> values set to specify the data subsets described.
>
>     I hope that helps.  If you have other particular questions, I'll try
> to answer them.
>
> Paul
>
> On 6/3/2018 2:09 PM, Barry O'Rourke wrote:
>
> Hello Paul, Jeff,
>
> We have also been investigating techniques for generating and utilizing
> GeoPackage metadata. Our first workflow provides a user with the ability to
> create an ISO 19115 metadata document that describes the GeoPackage
> overall. The user can then publish this ISO 19115 metadata document into a
> service registry and provide other users with the ability to discover
> GeoPackages of interest using a catalog search and determine suitability of
> use.
>
> We are also storing this metadata as an XML document in a relational table
> within the GeoPackage itself.
>
> Paul, we are very interested in investigating how you are using ISO 19115
> to describe "data" within the GeoPackage. Do you have a sample GeoPackage
> we could work with?
>
> How are we planning to document these approaches and make them available
> for discussion?
>
> Thanks,
>
> Barry
>
> On 4/20/2018 6:52 PM, Jeff Yutzler via Geopackage wrote:
>
> OK, I get it now. I haven't actually seen an example of many-to-many
> metadata in the wild so I didn't know that was possible.
> -Jeff
>
> On Fri, Apr 20, 2018 at 3:51 PM, Paul Daisey via Geopackage <
> geopackage at lists.opengeospatial.org> wrote:
>
>> All:
>>
>>     Pepijn has it right; the GeoPackage v1.0 metadata model had two
>> tables following a common relational database design for implementing many
>> to many relationships, which were needed to implement the hierarchical
>> metadata model defined in ISO 19115.  One metadata record can apply to many
>> data items (tables / rows / columns or any subset thereof), and one data
>> item can be described by many metadata records (e.g. from different
>> sources).
>>
>>     Cheers,
>>
>> Paul Daisey
>>
>> On 4/20/2018 3:19 PM, Pepijn Van Eeckhoudt via Geopackage wrote:
>>
>> Hi Jeff,
>>
>> Which tables do you mean exactly? gpkg_metadata and
>> gpkg_metadata_reference?
>>
>> One stores the metadata itself; the other is the association relationship
>> between the metadata and the data it describes. Splitting the two allows
>> reuse of metadata for multiple tables.
>>
>> If I remember correctly, Paul Daisy did most of the work on metadata so
>> he might be able to give you a better answer.
>>
>> Pepijn
>>
>> On 20 Apr 2018, at 21:10, Jeff Yutzler via Geopackage <
>> geopackage at lists.opengeospatial.org> wrote:
>>
>> Hello list.
>> Does anyone out there remember why we have two separate metadata tables
>> as part of the Metadata Extension (this was originally part of core)? I am
>> trying to produce guidance for this extension and as far as I can tell,
>> there is a 1:1 mapping between the two tables. Am I missing something?
>> -Jeff
>>
>> --
>> Jeff Yutzler
>> Image Matters LLC <http://www.imagemattersllc.com/>
>> Mobile: (703) 981-8753
>>
>>
>>
>> --
>> Paul Daisey 301-651-7148
>>
>>
>
>
> --
> Jeff Yutzler
> Image Matters LLC <http://www.imagemattersllc.com/>
> Mobile: (703) 981-8753
>
>
>
> --
> Paul Daisey 301-651-7148
>
>


-- 
Jeff Yutzler
Image Matters LLC <http://www.imagemattersllc.com/>
Mobile: (703) 981-8753
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