Mobile computing has become a way of life. Users carry their laptops, PDAs and other portable devices with them nearly constantly, whether across town or across a continent. Recent hardware innovations and improvements in chip technology have made this all possible.

However, unlike the advances in computing hardware, much of today's system software is not "mobile-ready." Such is the case with the replication service. Nomadic users require replication to store copies of critical data on their mobile machines, since disconnected or poorly connected machines must rely primarily on local resources. Existing replication services are designed for stationary environments, and do not provide mobile users with the capabilities they require. The mobile environment requires far different solutions than those previously proposed because nomadicity presents a fundamentally new and different computing paradigm.

Mobile users require several key features from the replication system: the ability for direct synchronization between any two replicas, the capability for widespread scaling and large numbers of replicas, and detailed control over what files reside on their local (mobile) replicas.

Under Travler, several file replication models have been enhanced or developed:

Rumor. Peer-oriented, optimistic, portable file replication for mobile computing

Roam. Scalable replication system for mobile and distributed computing

Optimal Propagation. Analyzes value gained (up-to-date) vs. cost (use of bandwidth)