Providing Secure Coordinated Access to Grid Services

Coordinating the cumulative use of distributed resources in a grid environment so that users do not consume too much is a difficult task. This paper presents one approach that we have implemented in Globus Toolkit version 4 (GT4), that uses an SQL database to hold coordination data, and policy decision points (PDPs) to make access control decisions about whether the users request for more resources can be granted or denied. When access is granted, obligations in the policy ensure that the coordination database is appropriately updated. In our initial implementation, the coordination service is embedded into the GT4 authorization chain as a custom PDP so that any web service can be provided with a security policy that provides a coordination capability. In the final section we describe how coordinated decision making could be more tightly integrated into a future version of GT.