postData.put("context", new JSONObject());
HttpRequest firstConnection = this.JsonRpc(getURLForMethod("session", "get_session_info"), "call", postData );
// We retrieve and store werkzeug session cookie
String cookies = firstConnection.header("Set-Cookie");
_cookies = HttpCookie.parse(cookies);
// We retrieve and store OpenERP session_id
JSONObject body = new JSONObject(firstConnection.body());
this._sessionId = (String) body.getJSONObject("result").get("session_id");