Flexible on-device service object replication with replets

Dong Zhou, Nayeem Islam, Ali Ismael

Abstract: An increasingly large amount of Web applications employ service objects such as Servlets to generate dynamic and personalized content. Existing caching infrastructures are not well suited for caching such content in mobile environments because of disconnection and weak connection. One possible approach to this problem is to replicate Web-related application logic to client devices. The challenges to this approach are to deal with client devices that exhibit huge divergence in resource availabilities, to support applications that have different data sharing and coherency requirements, and to accommodate the same application under different deployment environments. The Replet system targets these challenges. It uses client, server and application capability and preference information (CPI) to direct the replication of service objects to client devices: from the selection of a device for replication and populating the device with client-specific data, to choosing an appropriate replica to serve a given request and maintaining the desired state consistency among replicas. The Replet system exploits on-device replication to enable client-, server- and application-specific cost metrics for replica invocation and synchronization. We have implemented a prototype in the context of Servlet-based Web applications. Our experiment and simulation results demonstrate the viability and significant benefits of CPI-driven on-device service object replication.