Quickbooks / MySQL: syncronization / interface

I am designing a data collection application that will accept scanned values from a mobile computer and insert those records into a MySQL database. The items scanned are incoming pallets of inventory. Once these items are scanned and entered into the database, my client wants this inventory data to sync into Quickbooks (locally installed on a PC) to update the quantities of those items in their Quickbooks inventory. I need a data interface built to synchronize those inventory records to Quickbooks using one of the 3 following methods: 1. Manual sync - after user has scanned the material, they will execute a sync using a PHP/web based application 2. Scheduled sync - The database will be checked on a scheduled basis for new records and synced with Quickbooks accordingly 3. Realtime sync - A MySQL database trigger will be used to detect the inserted database rows and run a procedure to sync those records with Quickbooks The interface should update (add the scanned quantity to the existing quantity) existing Quickbooks items and create new items with the scanned quantity if the item doesn't already exist in Quickbooks. MySQL table will contain a sync_status column and error_message column for the following error handling and sync reporting: flagging each record as success or failure when syncing: a. "failure" status will be updated for the row when a synced record fails (failures should be reported with error details to the error_message column) b. "success" status will be updated for the row when a synced record completes successfully for that given row c. The default status of "sync" in the sync_status column will flag the record as eligible for sync by the program. Please provide your recommended interface method from the list above (Manual, scheduled or real time), the reason you choose this option (cost/time, reliability, etc) and quote according to that method. Please let me know if you have additional questions.