/**
* Build http-client object, execute request and return a response
*
* @param string $processed_query
* @param string $type Should be either "query" or "update"
*
* @return Http\Response|\Zend\Http\Response
* @throws Exception
*/
protected function executeQuery($processed_query, $type)
{
$client = Http::getDefaultHttpClient();
$client->resetParameters();
// Tell the server which response formats we can parse
$sparql_results_types = array('application/sparql-results+json' => 1.0, 'application/sparql-results+xml' => 0.8);
if ($type == 'update') {
// accept anything, as "response body of a […] update request is implementation defined"
// @see http://www.w3.org/TR/sparql11-protocol/#update-success
$accept = Format::getHttpAcceptHeader($sparql_results_types);
$client->setHeaders('Accept', $accept);
$client->setMethod('POST');
$client->setUri($this->updateUri);
$client->setRawData($processed_query);
$client->setHeaders('Content-Type', 'application/sparql-update');
} elseif ($type == 'query') {
$re = '(?:(?:\\s*BASE\\s*<.*?>\\s*)|(?:\\s*PREFIX\\s+.+:\\s*<.*?>\\s*))*' . '(CONSTRUCT|SELECT|ASK|DESCRIBE)[\\W]';
$result = null;
$matched = mb_eregi($re, $processed_query, $result);
if (false === $matched or count($result) !== 2) {
// non-standard query. is this something non-standard?
$query_verb = null;
} else {
$query_verb = strtoupper($result[1]);
}
if ($query_verb === 'SELECT' or $query_verb === 'ASK') {
// only "results"
$accept = Format::formatAcceptHeader($sparql_results_types);
} elseif ($query_verb === 'CONSTRUCT' or $query_verb === 'DESCRIBE') {
// only "graph"
$accept = Format::getHttpAcceptHeader();
} else {
// both
$accept = Format::getHttpAcceptHeader($sparql_results_types);
}
$client->setHeaders('Accept', $accept);
$encodedQuery = 'query=' . urlencode($processed_query);
// Use GET if the query is less than 2kB
// 2046 = 2kB minus 1 for '?' and 1 for NULL-terminated string on server
if (strlen($encodedQuery) + strlen($this->queryUri) <= 2046) {
$delimiter = $this->queryUri_has_params ? '&' : '?';
$client->setMethod('GET');
$client->setUri($this->queryUri . $delimiter . $encodedQuery);
} else {
// Fall back to POST instead (which is un-cacheable)
$client->setMethod('POST');
$client->setUri($this->queryUri);
$client->setRawData($encodedQuery);
$client->setHeaders('Content-Type', 'application/x-www-form-urlencoded');
}
} else {
throw new Exception('unexpected request-type: ' . $type);
}
return $client->request();
}
