How to Support Adaptive Mobile Applications

The Mobile Agent (MA) paradigm seems to be a promising solution for the design and development of distributed value-added services. However, mobility has added complexity to the design of application and requires new programming methodologies to allow agents to adapt their migration strategies to the current context and to react to unforeseen events. In this paper, we present a policy-based approach to mobility that allows application designers to express and govern mobility decisions at a high level of abstraction and to dynamically change the allocation of agents across the network nodes without intervention on the agent code. Policies are exploited to specify mobility strategies and allow to abstract away the specification of migration choices from the component code. The paper proposes a layered policy-aware architecture for MAs that allows to adapt the mobility behaviour of agents at different levels of abstraction depending on programmer expertise. Unskilled programmers can specify simply when and where to migrate agents, whereas skilled programmers can also specify which migration mechanism to select and activate to better accommodate to environment conditions. 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 envi-