Smartphones, tablets, netbooks and laptops are intensively used every day by a large part of the population. These devices--which are equipped with Wi-Fi interfaces--can form disconnected mobile ad hoc networks (DMANETs) dynamically. These networks may allow service providers, such as local authorities, to deliver new kinds of services in a wide area (e.g., a city) without resorting to the infrastructure-based networks of mobile phone operators. This paper presents OLFServ, a new location-aware forwarding protocol dedicated to service-oriented opportunistic computing in DMANETs. This protocol implements several self-pruning heuristics allowing mobile nodes to decide whether they efficiently contribute in the message delivery. The protocol has been implemented in a service-oriented middleware platform, and has been validated through simulations, which proved its efficiency.