| s | p_blank | o_blank |
|---|---|---|
| /id/geography/administration/lsoa/E01010121 | http://www.w3.org/1999/02/22-rdf-syntax-ns#type | geosparql: Geometry |
| /id/geography/administration/lsoa/E01010121 | geosparql: asWKT | MULTIPOLYGON (((-1.7739071199493288 52.505238953416104, -1.7744072448964185 52.504695531749284, -1.7734585867730528 52.50403436330801, -1.773904619609525 52.5036031619094, -1.7718176399500307 52.50237365118908, -1.7714425431019907 52.50181051365967, -1.7726486810772792 52.501601833554076, -1.7791821537752979 52.50117466182052, -1.7810681504057733 52.50113345650269, -1.7820126836577113 52.50149628598378, -1.7878696971183128 52.50240429576671, -1.7921025955224408 52.50299056329726, -1.7945131421496403 52.50285585925116, -1.7936569932878248 52.5035937885575, -1.789847724860464 52.50531317399407, -1.789424025473794 52.50457524599696, -1.7845525701319485 52.50359878378948, -1.7847156057533249 52.50460697982647, -1.783826168468665 52.50497941082994, -1.7821367553763887 52.504914367351205, -1.781906690732846 52.50428492592636, -1.7800065690217464 52.504610052236785, -1.7795973781633398 52.505033180816454, -1.7777312495473263 52.504814188421335, -1.7753648354688416 52.505648641124964, -1.7758408135676222 52.50632607323115, -1.7749424767182433 52.50685241293678, -1.7738634598528022 52.50578995803801, -1.7739071199493288 52.505238953416104))) |
The most flexible way to access the data is by using SPARQL, a query language, analagous to SQL for relational databases, for retrieving and manipulating data from graph databases like ours. We support SPARQL 1.1 query syntax. Many online tutorials are available.
To submit a SPARQL query from your code, you issue an HTTP GET or POST to our endpoint:http://opendatacommunities.org/sparql, with the query itself as a url-encoded parameter called query.
For example, to run the following simple SPARQL query and get the results as JSON:
SELECT * WHERE {?s ?p ?o} LIMIT 10Issue a POST to the endpoint, with the query in the body, and an Accept header of sparql-results+json:
POST http://opendatacommunities.org/sparql HTTP/1.1
Host: opendatacommunities.org
Accept: application/sparql-results+json
Content-Type: application/x-www-form-urlencoded
query=SELECT+%2A+WHERE+%7B%3Fs+%3Fp+%3Fo%7D+LIMIT+10Issue a GET to the following URL (note the .json extension - see the formats section for more detail on this):
GET http://opendatacommunities.org/sparql.json?query=SELECT+%2A+WHERE+%7B%3Fs+%3Fp+%3Fo%7D+LIMIT+10Scroll down to the end of this page for examples of both of these methods in a few different languages.
As with other aspects of our API, to get the data in different formats, you can use either (a) a format extension or (b) an HTTP Accept header. Available result formats depend on the type of SPARQL query. There are four main forms:
SELECT queries return tabular results, and the formats available reflect this:
| Format | Extensions | Accept Headers |
|---|---|---|
| XML | .xml |
application/xml, application/sparql-results+xml |
| JSON | .json |
application/json, application/sparql-results+json |
| Text | .txt, .text | text/plain |
| CSV | .csv | text/csv |
CONSTRUCT and DESCRIBE queries return graph data, so the results are available in the same formats as our resource APIs:
| Format | Extensions | Accept Headers |
|---|---|---|
| RDF/XML | .rdf | application/rdf+xml |
| N-triples | .nt, .txt, .text | application/n-triples, text/plain |
| Turtle | .ttl | text/turtle |
| JSON-LD | .json | application/ld+json, application/json |
ASK queries return a boolean result:
| Format | Extensions | Accept Headers |
|---|---|---|
| XML | .xml | application/xml, application/sparql-results+xml |
| JSON | .json | application/json, application/sparql-results+json |
| Text | .txt, .text | text/plain |
We accept page and per_page parameters for paginating the results of SELECT queries (we automatically modify your query to apply LIMIT and OFFSET clauses). For other query types (i.e. DESCRIBE, CONSTRUCT, ASK), pagination like this doesn’t make so much sense, so these parameters are ignored.
For requests made through the website (i.e. HTML format), the page size is defaulted to 20. For requests to our sparql endpoint for data formats (i.e. non-HTML), there will be no defaults for these parameters (i.e. results are unlimited. For performance reasons we generally advise LIMITing your query if possible).
You can parameterise your SPARQL by including %{tokens} in your queries, and providing values for the tokens in the request parameters.
Note that the following tokens are reserved and cannot be used as parameters for substitution:
controlleractionpageper_pageidcommitutf8queryOur servers are configured to allow access from all domains. This means that if you’re writing JavaScript to request data from our server in to a web page hosted on another domain, your browser should check this header and allow it.
If you need to support very old browsers, you can additionally pass a callback parameter and the results will be wrapped in that function. For example:
http://opendatacommunities.org/sparql.json?callback=myCallbackFunction&query=SELECT+%2A+WHERE+%7B%3Fs+%3Fp+%3Fo%7D+LIMIT+10This help topic on the jQuery website has more details.
Here’s a couple of examples running a query using the widely available cURL command line program.
Request the results as XML, using a POST:
curl -X POST -H "Accept: application/sparql-results+xml" -d "query=SELECT%20*%20WHERE%20%7B%3Fs%20%3Fp%20%3Fo%7D%20LIMIT%2010" http://opendatacommunities.org/sparqlRequest the results as JSON, using a GET:
curl -X GET -H "Accept: application/sparql-results+json" http://opendatacommunities.org/sparql?query=SELECT%20*%20WHERE%20%7B%3Fs%20%3Fp%20%3Fo%7D%20LIMIT%2010This example HTML page uses jQuery to issue a POST to our SPARQL endpoint, requesting the results as JSON.
<!DOCTYPE html>
<html lang='en'>
<head>
<script src='http://code.jquery.com/jquery-1.9.1.min.js'></script>
</head>
<body>
<script type='text/javascript'>
var query = 'SELECT * WHERE {?s ?p ?o} LIMIT 10';
var url = 'http://opendatacommunities.org/sparql.json';
$.ajax({
method: 'POST',
dataType: 'json',
url: url,
data: {query: query},
success: function(data) {
alert('success: ' + data.results.bindings.length + ' results');
console.log(data);
}
});
</script>
</body>
</html>