requirement to simulate order in oracle erp without creating it , checking if valid values are passe

hi all,

we are trying to integrate oracle erp version 11.5.10 with ATG e commerce portal and we have a need to simulate order for customer without creating it.for example , customer may choose a combination of bill to , ship to , item and certain other order related values which will get passed onto oracle in real time and we have to validate if the combination is valid for order placement in oracle erp. if not , we must pass back the errors associated back to atg in real time and ask the customer to make necessary changes. once a valid