Invoking Web service from iProc Workflow Notification,OAF Changes?

Question

I have a Requirement to Digitally sign the Requisition before the requisition is finally approved. We have a role in iProcurement, 'Certifying Official' , who would be the final approver. When the 'Certifying Official' receives the notification and clicks the 'Approve' button , we make a call to a web service to get the Digital signature and display a new page with the Requisition information back to the user. The user can choose to either save or cancel the Signature , if they save the signature we will display a confirmation page and comeback to the workflow process .
I was wondering what a better approach would be
1) Cusomize the OA Framework (Extend the controller) notification page and call the web service to digitally sign the Requisition and forward the user to a new page. Based on the user selection, I will have to re-direct to the new page or comeback and execute the workflow.
2) Customize Oracle workflow. If choose the workflow route, I was wondering If i would be able to display new pages based on the user action.
3) Have a link on the Notification page.
Thanks

Answer 1

You can use either of these two options. Even with using option 2 you have to extend the controller to fetch the nextPage from the workflow using appropriate API's. So better use the first option by extending the controller, call the webservice and forward to the required page.