This book addresses the technological challenges. It describes the problems, some existing solutions,
and proposes new ones. The first section deals with the problem of finding information in a network
lacking an infrastructure. Observe that this is different than the routing problem. It is harder in the sense
that even the identity of the receiver, that is the location of information, is unknown; but easier in the
sense that the information may be replicated and therefore routing to a single receiver is often not strictly
necessary. The proposed solutions combine query and information dissemination in an intelligent way.
P2P methods have been quite successful in the fixed world, and the second section explores adaptation
of the successful methods (e.g. overlays) to the mobile world. Section III continues this exploration,
with a distinction between mobile P2P systems that use an infrastructure, the ones that do not do so,
and the ones that use a hybrid strategy.