Business Processes for Web 1 Services are the new paradigm for virtual organization. In such cross organizational partnerships no business partner may guess a priori what kind of credentials will be sent by clients nor the clients may know a priori the needed credentials for the successful completion of a business process. This requires an interaction between server and clients. We propose a framework for managing the authorization interactions for business processes and a BPEL4WS based implementation using Collaxa server. Our model is based on interaction between servers and clients and exchange of requests for supplying or declining missing credentials.