diff -r 2b3247d02769 -r f55970e41793 server/src/app/Libraries/Sparql/SparqlClient.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/server/src/app/Libraries/Sparql/SparqlClient.php	Mon Oct 05 17:02:10 2015 +0200
@@ -0,0 +1,142 @@
+<?php
+namespace CorpusParole\Libraries\Sparql;
+
+use EasyRdf\Graph;
+use CorpusParole\Libraries\CorpusParoleException;
+use Config;
+use Log;
+
+/**
+ *
+ */
+class SparqlClient {
+
+    private $currentTransactionUrl = null;
+
+    function __construct($httpClient, $sparqlClient) {
+        $this->sparqlClient = $sparqlClient;
+        $this->httpClient = $httpClient;
+    }
+
+    private function getHttpClient() {
+        return $this->httpClient;
+    }
+
+    public function getCurrentTransactionUrl() {
+        return $this->currentTransactionUrl;
+    }
+
+    /**
+     * Start transaction.
+     * @return boolean true if a transaction was started, false otherwise
+     * @throws CorpusParoleException if the  transaction could not be stared
+     */
+    public function startTransaction() {
+        if(!is_null($this->currentTransactionUrl)) {
+            // We just continue the current transaction
+            return false;
+        }
+        //Log::debug('http_client base uri: ' . $this->getHttpClient()->getConfig('base_uri'));
+        $sesameRepository = config('corpusparole.sesame_repository');
+        $resp = $this->getHttpClient()->post("$sesameRepository/transactions");
+        //$resp = $this->getHttpClient()->post('transactions');
+        //TODO check errors
+        if($resp->getStatusCode() != 201) {
+            throw new CorpusParoleException("Error when starting transaction : "
+                . $resp->getStatusCode() . " - "
+                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);
+        }
+
+        $this->currentTransactionUrl = $resp->getHeader('Location')[0];
+
+        return true;
+    }
+
+    /**
+     * Rollback transaction.
+     * @return boolean true if a transaction was started, false otherwise
+     * @throws CorpusParoleException if the  transaction could not be rollbacked
+     */
+    public function rollback() {
+        if(is_null($this->currentTransactionUrl)) {
+            // We just continue the current transaction
+            return false;
+        }
+        $resp = $this->getHttpClient()->delete($this->currentTransactionUrl);
+
+        if($resp->getStatusCode() != 204) {
+            throw new CorpusParoleException("Could not cancel transaction : "
+                . $resp->getStatusCode() . " - "
+                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);
+        }
+        $this->currentTransactionUrl = null;
+
+        return true;
+    }
+
+    /**
+     * Commit transaction.
+     * @return boolean true if a transaction was started, false otherwise
+     * @throws CorpusParoleException if the  transaction could not be commited
+     */
+    public function commit() {
+        if(is_null($this->currentTransactionUrl)) {
+            // We just continue the current transaction
+            return false;
+        }
+        $resp = $this->getHttpClient()->put($this->currentTransactionUrl, ['query' => ['action' => 'COMMIT']]);
+        if($resp->getStatusCode() != 200) {
+            throw new CorpusParoleException("Could not commit transaction : "
+                . $resp->getStatusCode() . " - "
+                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);
+        }
+        $this->currentTransactionUrl = null;
+        return true;
+    }
+
+    protected function updateData($operation, Graph $graph)
+    {
+        $graphUri = $graph->getUri();
+        $query = "$operation DATA {";
+        if ($graphUri) {
+            $query .= "GRAPH <$graphUri> {";
+        }
+        $query .= $graph->serialise('ntriples');
+        if ($graphUri) {
+            $query .= "}";
+        }
+        $query .= '}';
+
+        $resp = $this->getHttpClient()->put(
+            $this->currentTransactionUrl, [
+                'query' => ['action' => 'UPDATE'],
+                'form_params'=> ['update' => $query],
+            ]
+        );
+        if($resp->getStatusCode() != 204) {
+            throw new CorpusParoleException("Could not update in transaction with operation $operation: "
+                . $resp->getStatusCode() . " - "
+                . $resp->getReasonPhrase() . " : " . $resp->getBody(), 1);
+        }
+    }
+
+    public function add(Graph $graph) {
+        $this->updateData('INSERT', $graph);
+    }
+
+    public function delete(Graph $graph) {
+        $this->updateData('DELETE', $graph);
+    }
+
+    /** Make a query to the SPARQL endpoint
+     *
+     * Just call and return EasyRdf\Sparql\Client::query
+     *
+     * @param string $query The query string to be executed
+     * @return object EasyRdf\Sparql\Result|EasyRdf\Graph Result of the query.
+     */
+    public function query($query) {
+        return $this->sparqlClient->query($query);
+    }
+
+}