We have a requirement where we need to create a new functionality called 'Purchase Proposal' . This will be created with reference to either a shopping cart, a Bid or Live auction and will be referred while creating a PO in SRM.
I am using the following approach for this.
1) Create a transaction in GUI . This will involve creation of Z tables, writing an ABAP code for the logic, creating a number range object etc.
2) After testing this transaction successfully in GUI, Create a web service & publish it on ITS by which this transaction can be accessed through webgui.
3) Create a business object for workflow
4) Create a workflow template for the business object.
5) Modify the standard functionality of PO processing so that Purchase Proposal can be entered while creating a PO and the data from it will flow into the PO
Is this approach correct or anything is missing?