Invoice approval agent is non-SAP user

[Nathan Fox]

Here is the scenario for an invoice approval flow using FI Prebooking
documents.  MM is not involved. SAP System is 4.6C. Business object FIPP.
 
1)Invoices are scanned and pre-booked in FI as a centralized function by
trained SAP users.
 
2)Approval of these invoices is decentralized and concerns about 100 non-SAP
users.  They don't have an SAP user logon, they have never used SAP.  The
users are however in the SAP organization structure and could be designated
quite nicely as the agent of approval for the pre-booked invoice.
 
3a)Proposed solution : My immediate reflex was to send an approval work-item
to the agent's MS Exchange inbox using the MAPI - SAP interface.  The user
doesn't realize he's "logging on" into the "complicated" SAP environment, he
just double clicks on an "Email-like" workitem.
 
3b)additional requirement after review : this SAP site does not want to buy
an additional 100 SAP user licences only to enable these agents to approve
pre-booked invoices, too costly.
 
Is it feasable to get around the SAP-User logon hurdle without creating an
equally complicated "gas works" solution?  The following scenario I submit
for peer-review and hope to stimulate some interesting discussion.
 
a) On creation of a pre-booked document(FIPP) an SAP Workflow is triggered.
b) Agents are found via OM and informed via Email of pending pre-booked
documents.  This Email is purely informative, it is not a workitem.
c) the SAP workflow goes into a "stand by" mode waiting for the events
"approved" or "rejected"
d) the informed agent receives the notification in MS Exchange of a pending
approval task, the agent starts a non-SAP application (perhaps VB of JAVA)
which accesses via a custom "GET_LIST" BAPI all the open pre-booked invoices
which are attributed to his/her HR personel number.  The logon takes place
accordingly with a generic RFC user.
e)the pre-booked document is displayed in the external application, after
which the user is prompted to approve or reject an invoice in which case the
corresponding "reject" "approve" method would be called via RFC.  We lack
SAP "BAPI" methods here.
f) the SAP workflow receives notification of approval or rejection and
terminates successfully.
 
Technically we have in-house competency in ABAP, RFC, ALE , BOR, and BAPI
programming. As "techies" we would love to try something "new" like this, a
technically cool solution.
 
My "functional" gut feeling bawks at the thought of a generic RFC user
approving and posting FI documents.
 
What do my workflow-peers think?
Are there other pitfalls, functional or technical, with the above scenario?
 
regards ( I'm on european time, I might take a while to respond)
Nate