function get_category_by_sku($sku)
{
    global $serviceUrl, $config, $service;
    $request = new MarketplaceWebServiceProducts_Model_GetProductCategoriesForSKURequest();
    $request->setSellerId(MWS_MERCHANG_ID);
    $request->withMarketplaceId(MWS_MARKETPLACE_ID);
    $request->setSellerSKU($sku);
    return invokeGetMyCategoryForSKU($service, $request);
}
 * responses without calling MarketplaceWebServiceProducts service.
 *
 * Responses are loaded from local XML files. You can tweak XML files to
 * experiment with various outputs during development
 *
 * XML files available under MarketplaceWebServiceProducts/Mock tree
 *
 ***********************************************************************/
// $service = new MarketplaceWebServiceProducts_Mock();
/************************************************************************
 * Setup request parameters and uncomment invoke to try out
 * sample for Get Product Categories For SKU Action
 ***********************************************************************/
// @TODO: set request. Action can be passed as MarketplaceWebServiceProducts_Model_GetProductCategoriesForSKU
$request = new MarketplaceWebServiceProducts_Model_GetProductCategoriesForSKURequest();
$request->setSellerId(MERCHANT_ID);
// object or array of parameters
invokeGetProductCategoriesForSKU($service, $request);
/**
 * Get Get Product Categories For SKU Action Sample
 * Gets competitive pricing and related information for a product identified by
 * the MarketplaceId and ASIN.
 *
 * @param MarketplaceWebServiceProducts_Interface $service instance of MarketplaceWebServiceProducts_Interface
 * @param mixed $request MarketplaceWebServiceProducts_Model_GetProductCategoriesForSKU or array of parameters
 */
function invokeGetProductCategoriesForSKU(MarketplaceWebServiceProducts_Interface $service, $request)
{
    try {
        $response = $service->GetProductCategoriesForSKU($request);
        echo "Service Response\n";