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GEMET API’s documentation

GEMET’s data is exposed through the Web for remote applications using XML (RDF/SKOS), HTTP and XML/RPC. The XML output is available at http://www.eionet.europa.eu/gemet/rdf .

What is a Concept?

GEMET is language neutral. The problem is that one language might use a single word to describe a concept. But in another language people use two or more terms to split the concept into several concepts. As they say; Eskimos have 40 different words for “snow”. In GEMET this extreme example would be 40 concepts, but the English terms would all be “snow”. Icelandic would have perhaps 15 words for snow, and therefore also some overlap. Since no language is so rich it has unique terms for all concepts, GEMET uses a number to distinguish the concepts from each other.

A concept URI is simply the thesaurus URI plus the concept number. E.g. http://www.eionet.europa.eu/gemet/concept/7769 . Currently it is just a string, but we want to make GEMET part of the Semantic Web and browsable as Linked Data. What this means is that if you visit a concept URI with a webbrowser, you’ll see a webpage. If you use a linked data browser, with an Accept-header of application/rdf+xml , then an RDF document will be returned.

Using the API as a ReST service

The methods below are described as method calls in simplified Java with the public keyword implied. If you want to use it as a ReST api. You first need the URL where the API is implemented. In GEMET it is http://www.eionet.europa.eu/gemet/ . Then you encode the parameters as a GET operation:

http://www.eionet.europa.eu/gemet/getTopmostConcepts?thesaurus_uri=http://www.eionet.europa.eu/gemet/theme/&language=es

ReST has the constraint on the API that the arguments can only be text strings. I.e. you can’t send structures over to the server. Likewise no polymorphism is possible.

Without specifying any additional parameter, the standard format of the output is JSON .

All JSON responses can also be wrapped as JSONP if you provide a jsonp argument. I.e.:

http://mydomain.info/getTopmostConcepts?thesaurus_uri=http://www.eionet.europa.eu/gemet/theme/&language=es&jsonp=callback

will wrap the JSON response in callback method call.

If you don’t specify a valid method name for the API(see API methods below) you will receive a 400 Bad Request Error.
If you don’t specify all the required parameters for these methods you will receive the same error.

When designing the API we have been careful not to mix up the URL of the method with the URL of the thesaurus. It is possible to install the application and GEMET database somewhere else (e.g. intranet) and then use it without being dependent on GEMET at http://www.eionet.europa.eu . I.e.:

http://mydomain.info/getTopmostConcepts?thesaurus_uri=http://www.eionet.europa.eu/gemet/theme/&language=es

must be possible.

Common methods for GEMET API

The following set of functions can be called by a Web application or Web page using either HTTP, where the parameters are specified in the query string or via XML/RPC. A combination of such function calls ensure the full retrieval of GEMET’s content.

WebService API methods

getTopmostConcepts ( URI thesaurus_uri [ , String language='en' ] )
Parameters:
  • thesaurus_uri – The thesaurus URI from which to retrieve concepts
  • language – The language in which the concepts are returned
Return type:

A list of dictionaries representing the concepts

The result from the method will be a list of concept structs that are determined to be top concepts of the thesaurus. The purpose is to make the thesaurus browsable. In principle all concepts that don’t have a broader definition would qualify. This method replaces fetchTopConcepts , fetchThemes and fetchGroups . To get the themes, you would call getTopmostConcepts('http://www.eionet.europa.eu/gemet/theme/', 'en') .

A URI is a subclass of string, potentially with some methods to manipulate the URI.

Examples:

http://www.eionet.europa.eu/gemet/getTopmostConcepts?thesaurus_uri=http://www.eionet.europa.eu/gemet/group/&language=en
http://www.eionet.europa.eu/gemet/getTopmostConcepts?thesaurus_uri=http://inspire.ec.europa.eu/theme/&language=en

getAllConceptRelatives ( URI concept_uri [ , URI target_thesaurus_uri , URI relation_uri ] )
Parameters:
  • concept_uri – A URI for the concept
  • target_thesaurus_uri – A URI for a thesaurus representing the namespace in which to look for relatives
  • relation_uri – A URI for the relation
Return type:

A list of dictionaries representing the concepts

This method will return a listing of relations for the given concept. The relation can be any relationship, but only direct relationships. The target_thesaurus_uri argument is optional. If it isn’t provided the relations can be to concepts in all thesauri in the database. The relation_uri argument is optional. It makes it possible to get only one type of relationship. The relation argument takes a URI, e.g. http://www.w3.org/2004/02/skos/core#narrower . See [ Known relations ] for a list of known relations. Only thesauri that are stored in the database are included.

The properties theme and hasConcept are inverse of each other. Meaning <Concept A> theme <Theme B> is the same as <Theme B> hasConcept <Concept A> . Therefore hasConcept is not actually listed in the database. Similarly are the properties group and hasConcept inverse. As are subGroupOf and subGroup .

Examples:

http://www.eionet.europa.eu/gemet/getAllConceptRelatives?concept_uri=http://www.eionet.europa.eu/gemet/group/234
http://www.eionet.europa.eu/gemet/getAllConceptRelatives?concept_uri=http://www.eionet.europa.eu/gemet/concept/6740
http://www.eionet.europa.eu/gemet/getAllConceptRelatives?concept_uri=http://inspire.ec.europa.eu/theme/ps

getRelatedConcepts ( URI concept_uri , URI relation_uri [ , String language='en' ] )
Parameters:
  • concept_uri – A URI for the concept
  • relation_uri – A URI for the relation
  • language – The language in which the concepts are returned
Return type:

A list of dictionaries representing the concepts

This method will return related concepts for the given concept. The relation_uri is mandatory, and must be one of the known relations listed in getAllConceptRelatives() . See [ Known relations ] for a list of known relations.

Example:

http://www.eionet.europa.eu/gemet/getRelatedConcepts?concept_uri=http://www.eionet.europa.eu/gemet/concept/913&relation_uri=http://www.w3.org/2004/02/skos/core%23broader&language=fr

hasRelation ( URI concept_uri , URI relation_uri , URI object_uri )
Parameters:
  • concept_uri – A URI for the concept representing the source
  • relation_uri – A URI for the relation
  • object_uri – A URI for the concept representing the target
Return type:

A boolean - True or False

Tests if the given concept_uri is in the relation relation_uri with the object_uri

Example:

http://www.eionet.europa.eu/gemet/hasRelation?concept_uri=http://www.eionet.europa.eu/gemet/concept/100&relation_uri=http://www.w3.org/2004/02/skos/core%23broader&object_uri=http://www.eionet.europa.eu/gemet/concept/13292

hasConcept ( URI concept_uri )
Parameters: concept_uri – A URI for the concept
Return type: A boolean - True or False

This function tests if the given concept_uri represents a valid concept or not, returning true or false.

Example:

http://www.eionet.europa.eu/gemet/hasConcept?concept_uri=http://www.eionet.europa.eu/gemet/concept/7970

getConcept ( URI concept_uri [ , String language='en' ] )
Parameters:
  • concept_uri – A URI for the concept
  • language – The language in which the concepts are returned
Return type:

A dictionary representing the concept

Returns a Concept struct filled out with information from the requested language.

Examples:

http://www.eionet.europa.eu/gemet/getConcept?concept_uri=http://inspire.ec.europa.eu/theme/ps&language=de
http://www.eionet.europa.eu/gemet/getConcept?concept_uri=http://www.eionet.europa.eu/gemet/concept/95&language=en

getAllTranslationsForConcept ( URI concept_uri , String property_uri )
Parameters:
  • concept_uri – A URI for the concept
  • property_uri – A URI for the property type one needs translations for
Return type:

A list of dictionaries containing the language and the property value

Returns all translations for a property of a given concept. The property is either a SKOS property URI, or an attribute name from the Concept class. Currently these are: definition, prefLabel, scopeNote, acronymLabel, and example. It is possible for a compliant server to have more information about a concept. These will show up as extra attributes in Concept objects, and it is legal for a client to ask about translations for any attribute of type LanguageString.

Property URI Concept attribute
http://www.w3.org/2004/02/skos/core#definition definition
http://www.w3.org/2004/02/skos/core#prefLabel preferredLabel
http://www.w3.org/2004/02/skos/core#scopeNote scopeNote
http://www.w3.org/2004/02/skos/core#altLabel nonPreferredLabels
http://www.w3.org/2004/02/skos/core#example example
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#acronymLabel acronymLabel

Why this business with property URIs? It is to provide an opportunity for someone who thinks in RDF terms to use the API in a natural way.

Example:

http://www.eionet.europa.eu/gemet/getAllTranslationsForConcept?concept_uri=http://www.eionet.europa.eu/gemet/concept/10126&property_uri=http://www.w3.org/2004/02/skos/core%23prefLabel

Note : When constructing a GET request of this type, the property URI must be URI-encoded, when it contains the “#” character (which has special meaning in a URI).

getConceptsMatchingKeyword ( String keyword , int search_mode [ , URI thesaurus_uri , String language ] )
Parameters:
  • keyword – A string representing the keyword to search for
  • search_mode

    An integer in the range 0 – 4 inclusive:

    0 – no wildcarding of any type (‘accident’ becomes ‘^accident$’). SQL syntax: term = ‘accident’
    1 – suffix regex (‘accident’ becomes ‘^accident.+$’). SQL syntax: term LIKE ‘accident%’
    2 – prefix regex (‘accident’ becomes ‘^.+accident$’). SQL syntax: term LIKE ‘%accident’
    3 – prefix/suffix combined (‘accident’ becomes ‘^.+accident.+$’). SQL syntax: term LIKE ‘%accident%’
    4 – auto search: each of the previous four expansions is tried in ascending order until a match is found
  • thesaurus_uri – Indicates which thesaurus to search in. If the argument is empty, all thesauri in the database are searched
  • language – The language is used both for specifying what language the keyword is and for returning the concept in the correct language
Return type:

A list of dictionaries representing the found concepts

The function retrieves a list of concepts matching a keyword for a particular thesaurus.

Example:

http://www.eionet.europa.eu/gemet/getConceptsMatchingKeyword?keyword=air&search_mode=0&thesaurus_uri=http://www.eionet.europa.eu/gemet/concept/&language=en

New in version 2.1: The language parameter is now set by default to ‘en’ .


getConceptsMatchingRegexByThesaurus ( String regex , URI thesaurus_uri [ , String language ] )
Parameters:
  • regex – A string representing the regex to search for
  • thesaurus_uri – Indicates which thesaurus to search in
  • language – The language is used both for specifying in what language to search for the regex and for returning the concept in the correct language
Return type:

A list of dictionaries representing the found concepts

Get a list of concepts matching a regex for a particular thesaurus. The language argument is used both for specifying what language to search in and for returning the concept in the correct language.

Example:

http://www.eionet.europa.eu/gemet/getConceptsMatchingRegexByThesaurus?regex=^air$&­thesaurus_uri=http://www.eionet.europa.eu/gemet/concept/&language=en

New in version 2.1: The language parameter is now set by default to ‘en’ .


getAvailableLanguages ( URI concept_uri )
Parameters: concept_uri – A URI for the concept
Return type: A list of strings representing the available languages (as codes)

This function returns the languages a concept’s preferred label is available in. A concept must have a preferred label before it can have any other property in that language.

Example:

http://www.eionet.europa.eu/gemet/getAvailableLanguages?concept_uri=http://inspire.ec.europa.eu/theme/ps

getSupportedLanguages ( URI thesaurus_uri )
Parameters: concept_uri – A URI for the thesaurus
Return type: A list of strings representing the available languages (as codes)

This function retrieves a list containing the language codes for all the languages supported by a certain namespace (concept, group, theme, etc.). Its parameter, thesaurus_uri , specifies the URI for the wanted namespace.

Example:

http://www.eionet.europa.eu/gemet/getSupportedLanguages?thesaurus_uri=http://www.eionet.europa.eu/gemet/concept/

getAvailableThesauri ( )
Return type: A list of strings representing the available thesauri

This function returns all the thesauri URIs the service knows of.

Example:

http://www.eionet.europa.eu/gemet/getAvailableThesauri

fetchThemes ( [ String language ] )
Parameters: language – The language in which the themes are returned.
Return type: A list of dictionaries representing the fetched themes

This function retrieves all the themes the service knows of. It is a convenience method that calls getTopmostConcepts('\http://www.eionet.europa.eu/gemet/theme/', language) .

Example:

http://www.eionet.europa.eu/gemet/fetchThemes?language=en

New in version 2.1: The language parameter is now set by default to ‘en’ .


fetchGroups ( [ String language ] )
Parameters: language – The language in which the groups are returned.
Return type: A list of dictionaries representing the fetched themes

This function retrieves all the groups the service knows of. It is a convenience method that calls getTopmostConcepts('\http://www.eionet.europa.eu/gemet/group/', language) .

Example:

http://www.eionet.europa.eu/gemet/fetchGroups?language=en

New in version 2.1: The language parameter is now set by default to ‘en’ .


fetchSuperGroups ( [ String language ] )

New in version 2.1: This is a new method.

Parameters: language – The language in which super groups are returned.
Return type: A list of dictionaries representing the fetched themes

This function retrieves all the supergroups the service knows of. In principle all groups that don’t have a broader definition would qualify. It is a convenience method that calls getTopmostConcepts('\http://www.eionet.europa.eu/gemet/supergroup/', language) .

Example:

http://www.eionet.europa.eu/gemet/fetchSuperGroups?language=en

Note : To get the children (narrower groups), you can then call for each of them getAllConceptRelatives(target_thesaurus_uri='http://www.eionet.europa.eu/gemet/group/') .

Known relations

Relation Description
http://www.w3.org/2004/02/skos/core#narrower Narrower concept
http://www.w3.org/2004/02/skos/core#broader Broader concept
http://www.w3.org/2004/02/skos/core#related Related, but not a synonym
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#theme Theme relationship of a concept. Implemented in RDF, but it is unclear whether it is relevant. Equivalent to broader, but a theme is not a broader concept of a concept
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#themeMember Theme member relationship of a concept. Equivalent to narrower, but a theme is not a narrower concept of a concept
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#hasConcept Source is a theme or group, target is a concept, equivalent to narrower
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#group Source is a concept, target is a group. Equivalent to broader
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#groupMember Source is a group, target is a concept. Equivalent to narrower
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#subGroupOf Source is a group, target is one of the four super groups. Equivalent to broader
http://www.eionet.europa.eu/gemet/2004/06/gemet-schema.rdf#subGroup Source is one of the four super groups, target is a group. Equivalent to narrower

Note : when using the RESTful API you have to encode the ‘#’ as %23 in URLs, otherwise the webbrowser assumes you’re referring to a fragment inside the result document.

Known thesauri

Thesauri Description
http://www.eionet.europa.eu/gemet/concept/ thesaurus URI for Concepts
http://www.eionet.europa.eu/gemet/theme/ thesaurus URI for Themes
http://www.eionet.europa.eu/gemet/group/ thesaurus URI for Groups
http://www.eionet.europa.eu/gemet/supergroup/ thesaurus URI for SuperGroups
http://inspire.ec.europa.eu/theme/ thesaurus URI for Inspire Themes

Note : To retrieve the available thesauri, use the function getAvailableThesauri()

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