Getting Current Inventory Listing on Amazon MWS

To get your current inventory listing on amazon do the following

Step 1. Run RequestReport with ReportType set to _GET_MERCHANT_LISTINGS_DATA_

$request = new MarketplaceWebService_Model_RequestReportRequest();
$request->setMarketplace(MARKETPLACE_ID);
$request->setMerchant(MERCHANT_ID);
$request->setReportType('_GET_MERCHANT_LISTINGS_DATA_');

Step 2: Run GetReportList

Step 3: Using the response from Step 2, match the ReportRequestIDs from 1 and 2 and extract the corresponding ReportID

Step 4: Use GetReport to retrieve the data for that specific ReportID which will include a flat file listing of all inventory you have currently loaded in to Amazon marketplace.