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.
Two APIs are offered: Keyword Search and Prefix Search. A hosted version of the Lookup service is available on the DBpedia server infrastructure.
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"
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"
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)
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
Download and configure the index
You can get our indexes from HERE
Run the server
`./run Server [PATH TO THE INDEX]/[VERSION]/`
`./run Server /opt/dbpedia-lookup/2015-04`
Note: The index file must be decompressed
- current - from Latest DBpedia Dump (2015-10)
Available languages (i18n working in progress):
- en - English
The server should now be running at http://localhost:1111
Rebuilding the index
Rebuilding an index is usually not required, if you only intend on running a local mirror of the service you can donwload a prebuilt index as outlined above.
To re-build the index you will require
- DBpedia datasets
- Wikistatsextractor output - wikistatsextractor is a drop-in replacement of pignlproc
Get the following DBpedia datasets
- redirects_en.nt (or .ttl)
- short_abstracts_en.nt (or .ttl)
- instance_types_en.nt (or .ttl)
- article_categories_en.nt (or .ttl)
Concatenate all data and sort by URI
This is necessary because indexing in sorted order is significantly faster.
cat instance_types_en.nt (or .ttl) \ short_abstracts_en.nt (or .ttl) \ article_categories_en.nt (or .ttl) \ instance_types_en.ttl \ instance_types_sdtyped_dbo_en.ttl \ instance_types_transitive_en.ttl | sort >all_dbpedia_data.nt (or .ttl)
Get the dataset redirects_en.nt (or .ttl)
Redirects are not indexed, but they are excluded as targets of lookup.
The indexer has to be run twice:
with the DBpedia data
./run Indexer lookup_index_dir redirects_en.nt (or .ttl) all_dbpedia_data.nt (or .ttl)
with the wikistatsextractor data
./run Indexer lookup_index_dir redirects_en.nt (or .ttl) pairCounts
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.