Application Domain Accounting for Roaming Services

The spectrum of Internet-based services offered to final users is continuously enlarging, by considering service provisioning to clients connected to either fixed networks or mobile ones. In addition, the organization requirements connected to the increasing capabilities of wireless access devices are deeply modifying the service provisioning process. On the one hand, 3G mobile networks should support services that present the same richness and variety of the ones provided to fixed environments. On the other hand, the availability of very heterogeneous portable devices is likely to change some aspects of service provisioning, for instance by forcing to consider service delivery anywhere and anytime with an ad-hoc dynamic adaptation to the properties of the current access terminals. This new perspective calls for services that can be provided to users while they roam in a globally distributed network with their wireless portable devices connected to local/global service providers (SPs) [1, 2]. Client roaming is a widely common telecom service functionality, which is supported by most cellular phone operators; we claim that a similar concept of client roaming needs to be extended to the emerging novel classes of Internet-based mobile services. Similarly as a phone user roams and seamlessly passes between possibly different network operators, roaming customers of Internetbased mobile services should subscribe to a specific service and should have the possibility to connect to the most suitable SP available, e.g., depending on the client location. Let us consider a city guide service allowing clients to get information about shops, restaurants, and cinemas. A user should have the possibility to subscribe to one single SP providing the city guide, and to access the service even while roaming in other cities where other SPs offer a similar service. In addition, tourist information should be dynamically adapted to fit the specific access device visualization capabilities and should be filtered according to the specified/exhibited user preferences. In the following, we indicate such novel class of services as 1 . Roaming service scenarios raise several challenging issues to investigate and solve. The paper specifically explores the accounting area, i.e., how to collect and manage the resource usage information in roaming service provisioning for charging and billing purposes. The resources to be considered in the accounting process are very heterogeneous in nature and in their possible implementation, spanning from used network bandwidth to consumed processor time and memory, from the size of actually received data to the exploited functions for dynamic adaptation. In the provisioning of roaming services, we can distinguish between the accounting part related to pure network connectivity and the accounting part associated with application-level service aspects. For instance, in the city guide service, the network operator can be interested in accounting roaming users for the time they exploit the network connectivity, but also the guide SPs can require to account them for the