About Java User Defined Routines

Hi, the bussines of calling web services from R4GL has been hard, and i need to give developers a simpler approach, so im changing the point of view to try java code, im reading about UDRs specially in java and how to work with it, does anybody has experience in creating java UDRs that call web services ? I want to know (in advance) if its possible. The idea then is to call this routines from R4GL (p-code) the same way you call a stored procedure, rigth ?