DBpedia Lookup 2016

DBpedia Lookup is a web service that can be used to look up DBpedia URIs by related keywords. Related means that either the label of a resource matches, or an anchor text that was frequently used in Wikipedia to refer to a specific resource matches (for example the resource http://dbpedia.org/resource/United_States can be looked up by the string "USA"). The results are ranked by the number of inlinks pointing from other Wikipedia pages at a result page.

Web APIs

Two APIs are offered: Keyword Search and Prefix Search. A hosted version of the Lookup service is available on the DBpedia server infrastructure.

Keyword Search

The Keyword Search API can be used to find related DBpedia resources for a given string. The string may consist of a single or multiple words.

Example: Places that have the related keyword "berlin"

http://lookup.dbpedia.org/api/search/KeywordSearch?QueryClass=place&QueryString=berlin

Prefix Search (i.e. Autocomplete)

The Prefix Search API can be used to implement autocomplete input boxes. For a given partial keyword like berl the API returns URIs of related DBpedia resources like http://dbpedia.org/resource/Berlin.

Example: Top five resources for which a keyword starts with "berl"

http://lookup.dbpedia.org/api/search/PrefixSearch?QueryClass=&MaxHits=5&QueryString=berl

Parameters

The query parameters accepted by the endpoints are

QueryString: a string for which a DBpedia URI should be found.
QueryClass: a DBpedia class from the Ontology that the results should have (for owl#Thing and untyped resource, leave this parameter empty).
MaxHits: the maximum number of returned results (default: 5)

JSON support

By default all data is returned as XML, the service also retuns JSON to any request including the Accept: application/json header.

Running a local mirror of the webservice

Clone and build DBpedia Lookup

git clone git://github.com/dbpedia/lookup.git
cd lookup
mvn clean install

Rebuilding the index

Rebuilding an index is required if you want to use the 2016 version of DBPedia.

To re-build the index you will require

* DBpedia datasets


### Get the following DBpedia datasets
from http://downloads.dbpedia.org/2016-10/core-i18n/en/

* redirects\_en.ttl (Redirects are not indexed, but they are excluded as targets of lookup.)
* short\_abstracts\_en.ttl
* instance\_types\_en.ttl  --> it is beter to rename this one to: core_instances.ttl
* article\_categories\_en.ttl

from http://downloads.dbpedia.org/2016-10/core/

* instance_types_en.ttl
* instance_types_lhd_dbo_en.ttl
* instance_types_transitive_en.ttl  

### Concatenate all data and sort by URI

This is necessary because indexing in sorted order is significantly faster.

      cat core_instances.ttl  \
          short_abstracts_en.ttl \
          article_categories_en.ttl \
          instance_types_en.ttl  \
          instance_types_lhd_dbo_en.ttl \
          instance_types_transitive_en.ttl | sort >all_dbpedia_data..ttl

Run Indexer

The indexer has to be run twice:

1. with the DBpedia data

        ./run Indexer lookup_index_dir redirects_en..ttl all_dbpedia_data.nt .ttl

(this code will make the segementation files needed to run dbpeida lookup)

Run the server

`./run Server lookup_index_dir`

lookup_index_dir is the directory created by Run Indexer (previous step)
E.g:

`./run Server ..`

Available languages (i18n working in progress):

en - English

but you can change the language by indexing other files

The server should now be running at http://localhost:1111

Support and feedback

The best way to get support or give feedback on the Lookup project is via the DBpedia discussion mailing list. More technical queries about the code base should be directed to the DBpedia developers mailing list.

The DBpedia wiki also has useful information on the project.

Maintainers

Kunal Jha @Kunal-Jha
Sandro Coelho @sandroacoelho
Pablo Mendes @pablomendes (less active)
Max Jakob @maxjakob (less active)
Matt Haynes @matth (less active)

bsteenwi/lookup