In this paper we propose a multi-agent based proactive service replication scheme for service oriented computing in mobile ad hoc environment. The proposed scheme ensures service availability and optimum resource usage in the network without compromising the QoS requirement of the service consumers. To achieve this we formalize the service-replication problem into distributed constraint optimization problem (DCOP) and solve it using GDL family based Max-Sum algorithm. To make the system proactive and self emerging, we use a mechanism similar to active random early detection (ARED), used in TCP for congestion avoidance and to enable scalability we divide the whole network into some zones. We notice that the proposed scheme offers better service availability, message overhead and resource utilisation compared to existing ones.