Spontaneous (or opportunistic) networks are multi-hop ad-hoc networks where nodes opportunistically exploit peer-to-peer contacts to share content and available resources in an impromptu way. Even if spontaneous networking has recently received growing interest, there is still the lack of impactful and wide-scale appli-cations fully exploiting its potential. We claim that this is due to the intrinsic complexity of spontaneous net-work management, unsuitable to be directly handled by application developers. Therefore, this paper proposes a novel easy-to-use middleware, called RAMP, for the autonomic, cross-, and application-layer management of spontaneous networks. RAMP enables the dynamic sharing of all resources available via multiple, hetero-geneous, intermittent, infrastructure-based, and ad-hoc links, which are orchestrated in a lightweight way to compose the multi-hop paths needed by sharing appli-cations at runtime. The RAMP prototype is a useful tool for the community of researchers in the field and can be rapidly deployed over real execution environ-ments. The reported experimental results demonstrate the feasibility of our approach and the limited RAMP overhead over common deployment scenarios.