Requisition and PO approval outside Oracle

Dear Friends

These days I am facing one surprising requirement from my client. They want all the procurement activities outside Oracle. through one custom web application.My client has the wishlist where they want to provide access of third party web application to all the user who are geographically dispersed and through this web application they want all the procurement activities to be done including  creation of requisition , approval , PO creation and approval , receipting .

They are expecting all the procurement activities to be then interfaced to Oracle only for information and accounting.They are on R12 instance and I can clearly see the number of challenges as below:-