  The increasing trend on wireless-connected devices makes opportunistic
networking a promising alternative to existing infrastructure-based networks.
However, on these networks there is neither guarantee about the availability of
the connections nor on the topology of the network. The development of
opportunistic applications, i.e., applications running over opportunistic
networks, is still in early stages. This is due to lack of tools to support the
process in such uncertain conditions. Indeed, many tools have been introduced
to study and characterize opportunistic networks, but none of them is focused
on helping developers to conceive opportunistic applications. In this paper, we
argue that the gap between opportunistic applications development and network
characterization can be filled with network emulation. First, this position
paper points out important challenges about the development of opportunistic
applications. Then, in order to cope with these challenges, it details a set of
requirements that an emulator should meet to allow the testing of such
applications.
