--- a/server/src/app/Libraries/Sparql/SparqlClient.php	Mon Apr 25 14:05:17 2016 +0200
+++ b/server/src/app/Libraries/Sparql/SparqlClient.php	Sat May 07 10:06:26 2016 +0200
@@ -121,11 +121,39 @@
     }
 
     public function add(Graph $graph) {
-        $this->updateData('INSERT', $graph);
+        return $this->updateData('INSERT', $graph);
     }
 
     public function delete(Graph $graph) {
-        $this->updateData('DELETE', $graph);
+        return $this->updateData('DELETE', $graph);
+    }
+
+    public function deleteWhere($whereClauses, string $graphUri = null) {
+
+        if(is_array($whereClause)) {
+            $whereClause = implode(" .", $whereClause);
+        }
+
+        if($graphUri) {
+            $whereClause = "GRAPH <$graphUri> { $whereClause }";
+        }
+
+        $query = "DELETE WHERE { $whereClause }";
+
+        // doc : http://rdf4j.org/doc/4/articles/REST-API/transaction-operations.docbook?view
+        // cf. bug : https://openrdf.atlassian.net/browse/SES-2295
+        // and PR https://bitbucket.org/openrdf/sesame/commits/62b680d8650caca7bc1673f6aaac48a5b6e85d23?at=2.8.x
+        // The put form has been chosen over the post, because it seems that this is the form choosed in the sesame http client
+        $resp = $this->getHttpClient()->put(
+            $this->currentTransactionUrl, [
+                'headers' => ["Content-Type" => "application/sparql-update; charset=utf-8"],
+                'query' => ['action' => 'UPDATE'],
+                'body' => $query,
+            ]
+        );
+
+        return $resp;
+
     }
 
     /** Make a query to the SPARQL endpoint