Our API library contains low level API classes and methods that allow you to send requests like asking for a form, or asking for a list of records (grid).
There classes (for example Gpf_Rpc_GridRequest, Gpf_Rpc_FormRequest) are general purpose classes to handle general requests.
Example of using low level API (PHP code):
// getting list of affiliates
$request = new Gpf_Rpc_GridRequest("Pap_Merchants_User_AffiliatesGridSimple", "getRows", $session);
$request->addFilter("search", Gpf_Data_Filter::LIKE, "bbb");
$request->sendNow();
$grid = $request->getGrid();
$recordset = $grid->getRecordset();
foreach($recordset as $rec) {
echo 'Affiliate name: '.$rec->get('firstname').' '.$rec->get('lastname').'<br>';
}