EOMP: an exactly once multicast protocol for distributed mobile systems

Abstract

Reliable multicast provides an elegant mechanism for structuring communication among closely cooperating entities. In a distributed mobile computing environment, disconnections and physical mobility of the mobile hosts (MHs) may result in the loss of messages. This makes the problem of ensuring reliable multicast difficult for MHs. Apart from ensuring reliable message delivery, guaranteeing exactly once message delivery greatly helps in conserving the battery power. Moreover, for transaction-based applications, total ordering of messages are semantically essential. In this report, an exactly once multicast protocol (called EOMP) with totally ordered message delivery is proposed. An unreliable wireless MAC level multicast is used for delivering the messages to the MHs and a novel mechanism for multicasting messages in the cellular network is proposed. An EOMP tolerates mobile support station (MSS) failure by making the MSS stateless. Dynamic host group membership is also supported by an EOMP. The performance of EOMP has been evaluated and compared with an existing an EOMP by simulation. The results of the simulation show that an EOMP has lower delay, lesser handoff, reduced buffer space overhead, and are more scalable. To establish the effectiveness of a reliable multicast protocol with totally ordered message delivery for mobile systems, two different applications viz., a real-time distributed collaborative text editor and a distributed image rendering application, were developed as case studies. The applications were easy to develop as mobility and disconnection were hidden from the application by an EOMP. The applications are also efficient as they use a powerful reliable multicast primitive for communication.