Difference between revisions of "GCat Background"

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(SoBigData.eu: Dataset Metadata)
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=== SoBigData.eu: Method Metadata ===
 
=== SoBigData.eu: Method Metadata ===

Revision as of 13:21, 27 June 2016

** THIS DOCUMENT IS A DRAFT **

gCube Data Catalogue.... using CKAN.

CKAN is a powerful data management system that makes data accessible – by providing tools to streamline publishing, sharing, finding and using data. CKAN is an open-source DMS (data management system) for powering data hubs and data portals. CKAN makes it easy to publish, share and use data see: http://ckan.org/

gCube Data Catalogue Metadata

A Metadata in the gCube Data Catalogue is made by two parts: CKAN's default metadata fields and gCube Metadata Profile.


CKAN's default metadata fields

Those are metadata fields common for all metadata types in the gCube Data Catalogue (and used by default in the CKAN platform).

Label Field Name (API) Definition Guidelines Example
Title* title Name given to the dataset. Short phrase, written in plain language. Should be sufficiently descriptive to allow for search and discovery. Aquaculture Production and Consumption in Africa (2011)
Description description Short description explaining the content and its origins. Description of a few sentences, written in plain language. Should,provide a sufficiently comprehensive overview of the resource for anyone,to understand its content, origins, and any continuing work on it. The,description can be written at the end, since it summarizes key,information from the other metadata fields. This dataset contains attributes of aquaculture production and,consumption for each of Africa’s provinces in 2011. The data was,provided by………
Tags tags An array of Taxonomic terms stored as tags Taxonomic terms Access to education, Bamboo
License* lincese_title the license that applies to published dataset.
Organization* organization Organization the datasets belongs to See list of organizations on

https://ckan-d-d4s.d4science.org/organization

D4Science
Version version Version of dataset Increase manually after editing 1.0
Author* Owner of dataset The person who created the dataset Joe Bloggs
Author Contact Contact details of owner The email or other contact details of the person who created the dataset. joe@example.com
Mantainer Mantainer of the dataset The person who maintains the dataset Joe Bloggs
Mantainer

Contact

Contact details of mantainer The email or other contact details of the person who maintains the dataset. joe@example.com

mandatory fields are marked with an asterisk (*)


gCube Metadata Profile

gCube Metadata Profile defines a Metadata schema XML-based for adding custom metadata fields.

A gCube Metadata Profile is composed by one Metadata Format (<metadataformat>) that contains one or many (<metadatafield>). The schema is the following:

<?xml version="1.0" encoding="UTF-8">
<metadataformat>
    <metadatafield>
        <fieldName>Name</fieldName>
        <mandatory>true</mandatory>
        <isBoolean>false</isBoolean>
        <defaulValue>default value</defaulValue>
        <note>shown as suggestions in the insert/update metadata form of CKAN</note>
        <vocabulary>
            <vocabularyField>field1</vocabularyField>
            <vocabularyField>field2</vocabularyField>
            <!-- ... others vocabulary fields -->
        </vocabulary>
        <validator>
            <regularExpression>a regular expression for validating values</regularExpression>
        </validator>
    </metadatafield>
     <!-- ... others metadata fields -->
</metadataformat>

It's possible to validate a Metadata Format schema using following DTD


<?xml version="1.0" encoding="UTF-8"?>
<!ELEMENT metadataformat (metadatafield+)>
<!ELEMENT metadatafield (fieldName, mandatory, isBoolean?, defaulValue?, note?, vocabulary?, validator?)>
<!ELEMENT fieldName (#PCDATA)>
<!ELEMENT mandatory (#PCDATA)>
<!ELEMENT isBoolean (#PCDATA)>  <!-- MUST BE (true|false) -->
<!ELEMENT defaulValue (#PCDATA)> 
<!ELEMENT note (#PCDATA)> 
<!ELEMENT vocabulary (vocabularyField+)> 
<!ELEMENT vocabularyField (#PCDATA)> 
<!ELEMENT validator (regularExpression)> 
<!ELEMENT regularExpression (#PCDATA)> 

A possible instance of Metadata Field (<metadatafield>):

<metadatafield>
   <fieldName>Accessibility</fieldName>
   <mandatory>true</mandatory>
   <defaulValue>virtual/public</defaulValue>
   <vocabulary>
       <vocabularyField>virtual/public</vocabularyField>
       <vocabularyField>virtual/private</vocabularyField>
       <vocabularyField>transactional</vocabularyField>
   </vocabulary>
</metadatafield>

SoBigData.eu: Dataset Metadata

The current list of fields characterising a SoBigData resource is available at https://docs.google.com/spreadsheets/d/1kuhvmDVKpmqt2foyCB9wDo3HgzoAiCuRQ8CjRS-DVOM/edit?usp=sharing

The following fields have been identified:

Label Field Name (API)
Internal Identifier
Creation Date
Last Modification
    <metadatafield>
        <fieldName>'''xxx'''</fieldName>
        <mandatory>true</mandatory>
        <isBoolean>false</isBoolean>
        <defaulValue>default value</defaulValue>
        <note>shown as suggestions in the insert/update metadata form of CKAN</note>
        <vocabulary>
            <vocabularyField>field1</vocabularyField>
            <vocabularyField>field2</vocabularyField>
            <!-- ... others vocabulary fields -->
        </vocabulary>
        <validator>
            <regularExpression>a regular expression for validating values</regularExpression>
        </validator>
    </metadatafield>

SoBigData.eu: Method Metadata

gCube Data Catalogue: Geo Harvesting

This extension contains plugins (ckanext-geonetwork and others) that add geospatial capabilities to CKAN (https://github.com/geosolutions-it/ckanext-geonetwork/wiki).

Several harvesters to import geospatial metadata into CKAN from other sources in ISO 19139 format and others has been created in gCube Data Catalogue. In particular all metadata created into gCube Geonetwork (GeoNetwork is the catalog application to manage spatially referenced resources generated into D4Science Infrastructure) are harvested through the 'Geoentwork Resolver' a "middle tier" able to:

Mapping (among fields) from an ISO19139 Metadata to Ckan Dataset via ckanext-geonetwork is showed in the following table:

ISO19139 Ckan Dataset
Title Title
Description Description
Digital Transfer Option Data and Resource
CI_OnlineResource
gmd:url URL
gmd:name Name
gmd:description Description
Descriptive Keywords
gmd:keyword Tag
Additional Info
bbox, metadata language, age,

reference system, etc.

key/value

gCube Data Catalogue: Ckan Connector