Mobile Social Network in Proximity (MSNP) is a new form of social network in which users are capable of interacting with their surroundings via their mobile devices in public mobile peer-to-peer (MP2P) environments. MSNP brings opportunity to people to meet new friends, share device content, and perform various social activities. However, as the fundamental topology of MSNP is based on public MP2P network, many challenges have arisen. Existing related works restrict the MP2P social network to operate in specific platforms and protocols. Enabling MSNP in a dynamic public MP2P also requires a more flexible loosely-coupled service-oriented solution. Applying the service-oriented MSNP environment will enhance the interoperability of MSNP participants. However, the latency issue while performing dynamic service discovery and the resource constraint issue of devices, prevent the efficiency of MP2P-based service-oriented MSNP systems. In this paper, we propose an adaptive mobile-hosted service-oriented mediation framework for MSNP. The framework supports proactive service discovery by using context-aware user preference prediction scheme to reduce the latency caused by the service discovery process. In order to resolve the resource constraint issue, the mediation framework applied the Enterprise Service Bus architecture to support the runtime resource changes, and utilise resource-aware workflow mechanism to enable the dynamic adjustment of the execution behaviour at runtime based on the combination of fuzzy set and cost and performance index scheme.