Policy Controlled Mobility

The mobility of software components seems an interesting solution for the deployment of web services and applications in the Internet global infrastructure and also in mobile ad-hoc networks. The network infrastructure already supports several forms of code mobility to make possible to dynamically reconfigure bindings between code fragments and locations where they are to be executed. However, more work is still to be done to facilitate the specification and the enforcement of the mobility behaviour of software components. The traditional approach to embed the migration strategy into the component at design time can not suit the dynamicity of the new network scenarios. Mobile components should instead be enhanced with the possibility to adapt their mobility behaviour to evolving application and environment conditions and to react to unforeseen events. To reach this goal, the paper proposes the adoption of policy based systems to abstract away the specification of migration strategies from the component code. This approach permits to change the mobility behaviour of components without intervention on the component code. We have experienced the dynamicity and flexibility of the proposed approach in the framework obtained by integrating a policy-based management system in a mobile agent environment.