In Verdi’s famous opera Rigoletto, mobility is compared to a feather in the
wind. The word “mobile” possesses a flavor of change, elusiveness, and dynamic
nature. Following this paradigm, mobile information systems provide
users and other systems with access to information resources and services over
a variety of different distribution channels. Mobile devices allow us to interact
with the information system over variable networks. The technical and
usage characteristics of mobile systems are highly variable with respect to the
characteristics of the users and of the context of use, therefore a high level
of flexibility is required. Such a flexibility requires the system to be able to
adapt at various levels, ranging from networks to services.