protected function linkData()
{
// use credential to access SPARQL server, if required
if ($this->username) {
HttpClient::useIdentity($this->username, $this->password);
}
if (!empty($this->endpoint) && !empty($this->constructor)) {
// create links to data
$sparql = new SparqlClient($this->endpoint);
$endpointQuery = $this->templateEngine->setTemplate($this->constructor . ' LIMIT {limit} OFFSET {offset}')->render();
$this->resultGraph = $sparql->query($endpointQuery);
// add queryResource to template vars
$this->templateEngine->addVar('queryResource', $this->endpoint . '?query=' . urlencode($endpointQuery));
// calculate if hasNextPage according pagingPolicy
$this->hasNextPage = $this->pagingPolicy == self::AGGRESSIVE ? $this->resultGraph->countTriples() == $this->context->getPageSize() : !$this->resultGraph->isEmpty();
}
return $this;
}
