Data replication can reduce access time and improve fault tolerance and load balancing. Typical requirements for a replica management system include an upper bound on replica Round Trip Time, scalability, reliability, self-management and selforganization, and ability to maintain consistency of mutable replicas. This article presents the design and a prototype implementation of a scalable, autonomous, service-oriented replica management framework for Globus Toolkit Version 4 using DKS. DKS is a structured peer-to-peer middleware. Grid nodes are integrated into a P2P network. The framework uses the ant metaphor and techniques of multi-agent systems for collaborative replica selection. We propose also a complimentary "background" service that collects access statistics and optimizes replica placement based on access pattern and replica lifetimes statistics. We have tested and profiled the prototype.