We simplify the above process and produce a review summary document. The overall system architecture is described in Figure 3 . The summary document stores data such as author information and evaluation results. This scenario is based on the future Web Services world on the Internet. The Web Services provided by the Web services provider are registered in the Broker's repository in XML format.
Broker returns appropriate service descriptions to the requester.
The overoall system architecture is described in Figure 4 . When returning the service description, the Broker uses the XML access control to enforce the access control policy. In this scenario, the XML access control is used in the client side to manage client's private information. When we send our private information such as an e-mail address and a phone number to Web servers, we have to be careful whether or not the receiving company deals with these private information securely and appropriately. Overall system architecture is described in Figure 5 .